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Nakamura, Shuichi, i Tohru Minamino. "Flagella-Driven Motility of Bacteria". Biomolecules 9, nr 7 (14.07.2019): 279. http://dx.doi.org/10.3390/biom9070279.
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The bacterial flagellum is a helical filamentous organelle responsible for motility. In bacterial species possessing flagella at the cell exterior, the long helical flagellar filament acts as a molecular screw to generate thrust. Meanwhile, the flagella of spirochetes reside within the periplasmic space and not only act as a cytoskeleton to determine the helicity of the cell body, but also rotate or undulate the helical cell body for propulsion. Despite structural diversity of the flagella among bacterial species, flagellated bacteria share a common rotary nanomachine, namely the flagellar motor, which is located at the base of the filament. The flagellar motor is composed of a rotor ring complex and multiple transmembrane stator units and converts the ion flux through an ion channel of each stator unit into the mechanical work required for motor rotation. Intracellular chemotactic signaling pathways regulate the direction of flagella-driven motility in response to changes in the environments, allowing bacteria to migrate towards more desirable environments for their survival. Recent experimental and theoretical studies have been deepening our understanding of the molecular mechanisms of the flagellar motor. In this review article, we describe the current understanding of the structure and dynamics of the bacterial flagellum.
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Yen, Jiun Y., Katherine M. Broadway i Birgit E. Scharf. "Minimum Requirements of Flagellation and Motility for Infection of Agrobacterium sp. Strain H13-3 by Flagellotropic Bacteriophage 7-7-1". Applied and Environmental Microbiology 78, nr 20 (3.08.2012): 7216–22. http://dx.doi.org/10.1128/aem.01082-12.
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ABSTRACTThe flagellotropic phage 7-7-1 specifically adsorbs toAgrobacteriumsp. strain H13-3 (formerlyRhizobium lupiniH13-3) flagella for efficient host infection. TheAgrobacteriumsp. H13-3 flagellum is complex and consists of three flagellin proteins: the primary flagellin FlaA, which is essential for motility, and the secondary flagellins FlaB and FlaD, which have minor functions in motility. Using quantitative infectivity assays, we showed that absence of FlaD had no effect on phage infection, while absence of FlaB resulted in a 2.5-fold increase in infectivity. AflaAdeletion strain, which produces straight and severely truncated flagella, experienced a significantly reduced infectivity, similar to that of aflaB flaDstrain, which produces a low number of straight flagella. A strain lacking all three flagellin genes is phage resistant. In addition to flagellation, flagellar rotation is required for infection. A strain that is nonmotile due to an in-frame deletion in the gene encoding the motor component MotA is resistant to phage infection. We also generated two strains with point mutations in themotAgene resulting in replacement of the conserved charged residue Glu98, which is important for modulation of rotary speed. A change to the neutral Gln caused the flagellar motor to rotate at a constant high speed, allowing a 2.2-fold-enhanced infectivity. A change to the positively charged Lys caused a jiggly motility phenotype with very slow flagellar rotation, which significantly reduced the efficiency of infection. In conclusion, flagellar number and length, as well as speed of flagellar rotation, are important determinants for infection by phage 7-7-1.
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Rabaan, Ali A., Ioannis Gryllos, Juan M. Tomás i Jonathan G. Shaw. "Motility and the Polar Flagellum Are Required for Aeromonas caviae Adherence to HEp-2 Cells". Infection and Immunity 69, nr 7 (1.07.2001): 4257–67. http://dx.doi.org/10.1128/iai.69.7.4257-4267.2001.
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ABSTRACT Aeromonas caviae is increasingly being recognized as a cause of gastroenteritis, especially among the young. The adherence of aeromonads to human epithelial cells in vitro has been correlated with enteropathogenicity, but the mechanism is far from well understood. Initial investigations demonstrated that adherence of A. caviae to HEp-2 cells was significantly reduced by either pretreating bacterial cells with an antipolar flagellin antibody or by pretreating HEp-2 cells with partially purified flagella. To precisely define the role of the polar flagellum in aeromonad adherence, we isolated the A. caviae polar flagellin locus and identified five polar flagellar genes, in the order flaA, flaB, flaG, flaH, and flaJ. Each gene was inactivated using a kanamycin resistance cartridge that ensures the transcription of downstream genes, and the resulting mutants were tested for motility, flagellin expression, and adherence to HEp-2 cells. N-terminal amino acid sequencing, mutant analysis, and Western blotting demonstrated that A. caviae has a complex flagellum filament composed of two flagellin subunits encoded by flaAand flaB. The predicted molecular mass of both flagellins was ∼31,700 Da; however, their molecular mass estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was ∼35,500 Da. This aberrant migration was thought to be due to their glycosylation, since the proteins were reactive in glycosyl group detection assays. Single mutations in either flaA orflaB did not result in loss of flagella but did result in decreased motility and adherence by approximately 50%. Mutation offlaH, flaJ, or both flagellin genes resulted in the complete loss of motility, flagellin expression, and adherence. However, mutation of flaG did not affect motility but did significantly reduce the level of adherence. Centrifugation of the flagellate mutants (flaA, flaB, and flaG) onto the cell monolayers did not increase adherence, whereas centrifugation of the aflagellate mutants (flaH, flaJ, and flaA flaB) increased adherence slightly. We conclude that maximum adherence of A. caviae to human epithelial cells in vitro requires motility and optimal flagellar function.
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Campodónico, Victoria L., Nicolás J. Llosa, Martha Grout, Gerd Döring, Tomás Maira-Litrán i Gerald B. Pier. "Evaluation of Flagella and Flagellin of Pseudomonas aeruginosa as Vaccines". Infection and Immunity 78, nr 2 (7.12.2009): 746–55. http://dx.doi.org/10.1128/iai.00806-09.
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ABSTRACT Pseudomonas aeruginosa is a serious pathogen in hospitalized, immunocompromised, and cystic fibrosis (CF) patients. P. aeruginosa is motile via a single polar flagellum made of polymerized flagellin proteins differentiated into two major serotypes: a and b. Antibodies to flagella delay onset of infection in CF patients, but whether immunity to polymeric flagella and that to monomeric flagellin are comparable has not been addressed, nor has the question of whether such antibodies might negatively impact Toll-like receptor 5 (TLR5) activation, an important component of innate immunity to P. aeruginosa. We compared immunization with flagella and that with flagellin for in vitro effects on motility, opsonic killing, and protective efficacy using a mouse pneumonia model. Antibodies to flagella were superior to antibodies to flagellin at inhibiting motility, promoting opsonic killing, and mediating protection against P. aeruginosa pneumonia in mice. Protection against the flagellar type strains PAK and PA01 was maximal, but it was only marginal against motile clinical isolates from flagellum-immunized CF patients who nonetheless became colonized with P. aeruginosa. Purified flagellin was a more potent activator of TLR5 than were flagella and also elicited higher TLR5-neutralizing antibodies than did immunization with flagella. Antibody to type a but not type b flagella or flagellin inhibited TLR5 activation by whole bacterial cells. Overall, intact flagella appear to be superior for generating immunity to P. aeruginosa, and flagellin monomers might induce antibodies capable of neutralizing innate immunity due to TLR5 activation, but solid immunity to P. aeruginosa based on flagellar antigens may require additional components beyond type a and type b proteins from prototype strains.
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Arora, Shiwani K., Alice N. Neely, Barbara Blair, Stephen Lory i Reuben Ramphal. "Role of Motility and Flagellin Glycosylation in the Pathogenesis of Pseudomonas aeruginosa Burn Wound Infections". Infection and Immunity 73, nr 7 (lipiec 2005): 4395–98. http://dx.doi.org/10.1128/iai.73.7.4395-4398.2005.
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ABSTRACT In this study, we tested the contribution of flagellar motility, flagellin structure, and its glycosylation in Pseudomonas aeruginosa using genetically defined flagellar mutants. All mutants and their parent strains were tested in a burned-mouse model of infection. Motility and glycosylation of the flagellum appear to be important determinants of flagellar-mediated virulence in this model. This is the first report where genetically defined flagellar variants of P. aeruginosa were tested in the burned-mouse model of infection.
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Kim, Yun-Kyeong, i Linda L. McCarter. "Analysis of the Polar Flagellar Gene System ofVibrio parahaemolyticus". Journal of Bacteriology 182, nr 13 (1.07.2000): 3693–704. http://dx.doi.org/10.1128/jb.182.13.3693-3704.2000.
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ABSTRACT Vibrio parahaemolyticus has dual flagellar systems adapted for locomotion under different circumstances. A single, sheathed polar flagellum propels the swimmer cell in liquid environments. Numerous unsheathed lateral flagella move the swarmer cell over surfaces. The polar flagellum is produced continuously, whereas the synthesis of lateral flagella is induced under conditions that impede the function of the polar flagellum, e.g., in viscous environments or on surfaces. Thus, the organism possesses two large gene networks that orchestrate polar and lateral flagellar gene expression and assembly. In addition, the polar flagellum functions as a mechanosensor controlling lateral gene expression. In order to gain insight into the genetic circuitry controlling motility and surface sensing, we have sought to define the polar flagellar gene system. The hierarchy of regulation appears to be different from the polar system of Caulobacter crescentus or the peritrichous system of enteric bacteria but is pertinent to many Vibrio andPseudomonas species. The gene identity and organization of 60 potential flagellar and chemotaxis genes are described. Conserved sequences are defined for two classes of polar flagellar promoters. Phenotypic and genotypic analysis of mutant strains with defects in swimming motility coupled with primer extension analysis of flagellar and chemotaxis transcription provides insight into the polar flagellar organelle, its assembly, and regulation of gene expression.
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Shelswell, Kristopher J., Terumi A. Taylor i J. Thomas Beatty. "Photoresponsive Flagellum-Independent Motility of the Purple Phototrophic Bacterium Rhodobacter capsulatus". Journal of Bacteriology 187, nr 14 (lipiec 2005): 5040–43. http://dx.doi.org/10.1128/jb.187.14.5040-5043.2005.
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ABSTRACT We report the discovery of photoresponsive, flagellum-independent motility of the α-proteobacterium Rhodobacter capsulatus, a nonsulfur purple phototrophic bacterium. This motility takes place in the 1.5% agar-glass interface of petri plates but not in soft agar, and cells move toward a light source. The appearances of motility assay plates inoculated with wild-type or flagellum-deficient mutants indicate differential contributions from flagellar and flagellum-independent mechanisms. Electron microscopy confirmed the absence of flagella in flagellar mutants and revealed the presence of pilus-like structures at one pole of wild-type and mutant cells. We suggest that R. capsulatus utilizes a flagellum-independent, photoresponsive mechanism that resembles twitching motility to move in a line away from the point of inoculation toward a light source.
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Marathe, Sandhya Amol, Arjun Balakrishnan, Vidya Devi Negi, Deepika Sakorey, Nagasuma Chandra i Dipshikha Chakravortty. "Curcumin Reduces the Motility of Salmonella enterica Serovar Typhimurium by Binding to the Flagella, Thereby Leading to Flagellar Fragility and Shedding". Journal of Bacteriology 198, nr 13 (18.04.2016): 1798–811. http://dx.doi.org/10.1128/jb.00092-16.
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ABSTRACTOne of the important virulence properties of the pathogen is its ability to travel to a favorable environment, cross the viscous mucus barrier (intestinal barrier for enteric pathogens), and reach the epithelia to initiate pathogenesis with the help of an appendage, like flagella. Nonetheless, flagella can act as an “Achilles heel,” revealing the pathogen's presence to the host through the stimulation of innate and adaptive immune responses. We assessed whether curcumin, a dietary polyphenol, could alter the motility ofSalmonella, a foodborne pathogen. It reduced the motility ofSalmonella entericaserovar Typhimurium by shortening the length of the flagellar filament (from ∼8 μm to ∼5 μm) and decreasing its density (4 or 5 flagella/bacterium instead of 8 or 9 flagella/bacterium). Upon curcumin treatment, the percentage of flagellated bacteria declined from ∼84% to 59%. However, no change was detected in the expression of the flagellin gene and protein. A fluorescence binding assay demonstrated binding of curcumin to the flagellar filament. This might make the filament fragile, breaking it into smaller fragments. Computational analysis predicted the binding of curcumin, its analogues, and its degraded products to a flagellin molecule at an interface between domains D1 and D2. Site-directed mutagenesis and a fluorescence binding assay confirmed the binding of curcumin to flagellin at residues ASN120, ASP123, ASN163, SER164, ASN173, and GLN175.IMPORTANCEThis work, to our knowledge the first report of its kind, examines how curcumin targets flagellar density and affects the pathogenesis of bacteria. We found that curcumin does not affect any of the flagellar synthesis genes. Instead, it binds to the flagellum and makes it fragile. It increases the torsional stress on the flagellar filament that then breaks, leaving fewer flagella around the bacteria. Flagella, which are crucial ligands for Toll-like receptor 5, are some of the most important appendages ofSalmonella. Curcumin is an important component of turmeric, which is a major spice used in Asian cooking. The loss of flagella can, in turn, change the pathogenesis of bacteria, making them more robust and fit in the host.
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Zheng, Xin, Hongjuan Bai, Ye Tao, Mounia Achak, Yannick Rossez i Edvina Lamy. "Flagellar Phenotypes Impact on Bacterial Transport and Deposition Behavior in Porous Media: Case of Salmonella enterica Serovar Typhimurium". International Journal of Molecular Sciences 23, nr 22 (21.11.2022): 14460. http://dx.doi.org/10.3390/ijms232214460.
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Bacterial contamination of groundwater has always been an ecological problem worthy of attention. In this study, Salmonella enterica serovar Typhimurium with different flagellar phenotypes mainly characterized during host-pathogen interaction were analyzed for their transport and deposition behavior in porous media. Column transport experiments and a modified mobile-immobile model were applicated on different strains with flagellar motility (wild-type) or without motility (ΔmotAB), without flagella (ΔflgKL), methylated and unmethylated flagellin (ΔfliB), and different flagella phases (fliCON, fljBON). Results showed that flagella motility could promote bacterial transport and deposition due to their biological advantages of moving and attaching to surfaces. We also found that the presence of non-motile flagella improved bacterial adhesion according to a higher retention rate of the ΔmotAB strain compared to the ΔflgKL strain. This indicated that bacteria flagella and motility both had promoting effects on bacterial deposition in sandy porous media. Flagella phases influenced the bacterial movement; the fliCON strain went faster through the column than the fljBON strain. Moreover, flagella methylation was found to favor bacterial transport and deposition. Overall, flagellar modifications affect Salmonella enterica serovar Typhimurium transport and deposition behavior in different ways in environmental conditions.
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Martinez, Raquel M., Madushini N. Dharmasena, Thomas J. Kirn i Ronald K. Taylor. "Characterization of Two Outer Membrane Proteins, FlgO and FlgP, That Influence Vibrio cholerae Motility". Journal of Bacteriology 191, nr 18 (10.07.2009): 5669–79. http://dx.doi.org/10.1128/jb.00632-09.
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ABSTRACT Vibrio cholerae is highly motile by the action of a single polar flagellum. The loss of motility reduces the infectivity of V. cholerae, demonstrating that motility is an important virulence factor. FlrC is the sigma-54-dependent positive regulator of flagellar genes. Recently, the genes VC2206 (flgP) and VC2207 (flgO) were identified as being regulated by FlrC via a microarray analysis of an flrC mutant (D. C. Morris, F. Peng, J. R. Barker, and K. E. Klose, J. Bacteriol. 190:231-239, 2008). FlgP is reported to be an outer membrane lipoprotein required for motility that functions as a colonization factor. The study reported here focuses on the characterization of flgO, the first gene in the flgOP operon. We show that FlgO and FlgP are important for motility, as strains with mutations in the flgOP genes have reduced motility phenotypes. The flgO and flgP mutant populations display fewer motile cells as well as reduced numbers of flagellated cells. The flagella produced by the flgO and flgP mutant strains are shorter in length than the wild-type flagella, which can be restored by inhibiting rotation of the flagellum. FlgO is an outer membrane protein that localizes throughout the membrane and not at the flagellar pole. Although FlgO and FlgP do not specifically localize to the flagellum, they are required for flagellar stability. Due to the nature of these motility defects, we established that the flagellum is not sufficient for adherence; rather, motility is the essential factor required for attachment and thus colonization by V. cholerae O1 of the classical biotype. This study reveals a novel mechanism for which the outer membrane proteins FlgO and FlgP function in motility to mediate flagellar stability and influence attachment and colonization.
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McCarter, Linda L. "Polar Flagellar Motility of theVibrionaceae". Microbiology and Molecular Biology Reviews 65, nr 3 (1.09.2001): 445–62. http://dx.doi.org/10.1128/mmbr.65.3.445-462.2001.
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SUMMARY Polar flagella of Vibrio species can rotate at speeds as high as 100,000 rpm and effectively propel the bacteria in liquid as fast as 60 μm/s. The sodium motive force powers rotation of the filament, which acts as a propeller. The filament is complex, composed of multiple subunits, and sheathed by an extension of the cell outer membrane. The regulatory circuitry controlling expression of the polar flagellar genes of members of the Vibrionaceae is different from the peritrichous system of enteric bacteria or the polar system of Caulobacter crescentus. The scheme of gene control is also pertinent to other members of the gamma purple bacteria, in particular to Pseudomonas species. This review uses the framework of the polar flagellar system of Vibrio parahaemolyticus to provide a synthesis of what is known about polar motility systems of the Vibrionaceae. In addition to its propulsive role, the single polar flagellum of V. parahaemolyticus is believed to act as a tactile sensor controlling surface-induced gene expression. Under conditions that impede rotation of the polar flagellum, an alternate, lateral flagellar motility system is induced that enables movement through viscous environments and over surfaces. Although the dual flagellar systems possess no shared structural components and although distinct type III secretion systems direct the simultaneous placement and assembly of polar and lateral organelles, movement is coordinated by shared chemotaxis machinery.
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Kirov, Sylvia M., Marika Castrisios i Jonathan G. Shaw. "Aeromonas Flagella (Polar and Lateral) Are Enterocyte Adhesins That Contribute to Biofilm Formation on Surfaces". Infection and Immunity 72, nr 4 (kwiecień 2004): 1939–45. http://dx.doi.org/10.1128/iai.72.4.1939-1945.2004.
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ABSTRACT Aeromonas spp. (gram-negative, aquatic bacteria which include enteropathogenic strains) have two distinct flagellar systems, namely a polar flagellum for swimming in liquid and multiple lateral flagella for swarming over surfaces. Only ∼60% of mesophilic strains can produce lateral flagella. To evaluate flagellar contributions to Aeromonas intestinal colonization, we compared polar and lateral flagellar mutant strains of a diarrheal isolate of Aeromonas caviae for the ability to adhere to the intestinal cell lines Henle 407 and Caco-2, which have the characteristic features of human intestinal enterocytes. Strains lacking polar flagella were virtually nonadherent to these cell lines, while loss of the lateral flagellum decreased adherence by ∼60% in comparison to the wild-type level. Motility mutants (unable to swim or swarm in agar assays) had adhesion levels of ∼50% of wild-type values, irrespective of their flagellar expression. Flagellar mutant strains were also evaluated for the ability to form biofilms in a borosilicate glass tube model which was optimized for Aeromonas spp. (broth inoculum, with a 16- to 20-h incubation at 37°C). All flagellar mutants showed a decreased ability to form biofilms (at least 30% lower than the wild type). For the chemotactic motility mutant cheA, biofilm formation decreased >80% from the wild-type level. The complementation of flagellar phenotypes (polar flagellar mutants) restored biofilms to wild-type levels. We concluded that both flagellar types are enterocyte adhesins and need to be fully functional for optimal biofilm formation.
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Filip’echeva, Yulia A., Andrei V. Shelud’ko, Alexei G. Prilipov, Gennady L. Burygin, Elizaveta M. Telesheva, Stella S. Yevstigneyeva, Marina P. Chernyshova, Lilia P. Petrova i Elena I. Katsy. "Plasmid AZOBR_p1-borne fabG gene for putative 3-oxoacyl-[acyl-carrier protein] reductase is essential for proper assembly and work of the dual flagellar system in the alphaproteobacterium Azospirillum brasilense Sp245". Canadian Journal of Microbiology 64, nr 2 (luty 2018): 107–18. http://dx.doi.org/10.1139/cjm-2017-0561.
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Azospirillum brasilense can swim and swarm owing to the activity of a constitutive polar flagellum (Fla) and inducible lateral flagella (Laf), respectively. Experimental data on the regulation of the Fla and Laf assembly in azospirilla are scarce. Here, the coding sequence (CDS) AZOBR_p1160043 (fabG1) for a putative 3-oxoacyl-[acyl-carrier protein (ACP)] reductase was found essential for the construction of both types of flagella. In an immotile leaky Fla− Laf− fabG1::Omegon-Km mutant, Sp245.1610, defects in flagellation and motility were fully complemented by expressing the CDS AZOBR_p1160043 from plasmid pRK415. When pRK415 with the cloned CDS AZOBR_p1160045 (fliC) for a putative 65.2 kDa Sp245 Fla flagellin was transferred into the Sp245.1610 cells, the bacteria also became able to assemble a motile single flagellum. Some cells, however, had unusual swimming behavior, probably because of the side location of the organelle. Although the assembly of Laf was not restored in Sp245.1610 (pRK415-p1160045), this strain was somewhat capable of swarming motility. We propose that the putative 3-oxoacyl-[ACP] reductase encoded by the CDS AZOBR_p1160043 plays a role in correct flagellar location in the cell envelope and (or) in flagellar modification(s), which are also required for the inducible construction of Laf and for proper swimming and swarming motility of A. brasilense Sp245.
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Khan, Shahid. "Freeze-fracture views of membrane motors of bacteria". Proceedings, annual meeting, Electron Microscopy Society of America 51 (1.08.1993): 54–55. http://dx.doi.org/10.1017/s0424820100146114.
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The locomotory organelles of many bacteria are long, helical filaments called flagella. Bacterial flagella rotate. Flagellar rotation is driven by a molecular motor that is part of the membrane embedded flagellar base and fueled by electrochemical proton (or sodium) gradients. Rapid-freeze electron microscopy has revealed that rings of intramembrane particles found clustered around flagellar bases are a key structural module of this motor.The morphology of the ring particles provides clues to their function. The particles are located in the cytoplasmic membrane across which the electrochemical gradients that energize flagellar rotation are maintained. In Escherichia coli, in addition to proteins needed for assembly of the flagellum, two proteins, MotA and MotB, are required for motility. MotA conducts protons across membranes and interacts with MotB, a protein with a large periplasmic domain. In non-motile mutants lacking MotA and MotB, flagellar bases lack the particle rings. Plasmid based expression of both MotA and MotB is necessary for restoration of motility and the ring structures.
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Fulano, Alex M., Danyu Shen, Miki Kinoshita, Shan-Ho Chou i Guoliang Qian. "The Homologous Components of Flagellar Type III Protein Apparatus Have Acquired a Novel Function to Control Twitching Motility in a Non-Flagellated Biocontrol Bacterium". Biomolecules 10, nr 5 (7.05.2020): 733. http://dx.doi.org/10.3390/biom10050733.
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The bacterial flagellum is one of the best-studied surface-attached appendages in bacteria. Flagellar assembly in vivo is promoted by its own protein export apparatus, a type III secretion system (T3SS) in pathogenic bacteria. Lysobacter enzymogenes OH11 is a non-flagellated soil bacterium that utilizes type IV pilus (T4P)-driven twitching motility to prey upon nearby fungi for food. Interestingly, the strain OH11 encodes components homologous to the flagellar type III protein apparatus (FT3SS) on its genome, but it remains unknown whether this FT3SS-like system is functional. Here, we report that, despite the absence of flagella, the FT3SS homologous genes are responsible not only for the export of the heterologous flagellin in strain OH11 but also for twitching motility. Blocking the FT3SS-like system by in-frame deletion mutations in either flhB or fliI abolished the secretion of heterologous flagellin molecules into the culture medium, indicating that the FT3SS is functional in strain OH11. A deletion of flhA, flhB, fliI, or fliR inhibited T4P-driven twitching motility, whereas neither that of fliP nor fliQ did, suggesting that FlhA, FlhB, FliI, and FliR may obtain a novel function to modulate the twitching motility. The flagellar FliI ATPase was required for the secretion of the major pilus subunit, PilA, suggesting that FliI would have evolved to act as a PilB-like pilus ATPase. These observations lead to a plausible hypothesis that the non-flagellated L. enzymogenes OH11 could preserve FT3SS-like genes for acquiring a distinct function to regulate twitching motility associated with its predatory behavior.
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Molofsky, A. B., L. M. Shetron-Rama i Michele S. Swanson. "Components of the Legionella pneumophila Flagellar Regulon Contribute to Multiple Virulence Traits, Including Lysosome Avoidance and Macrophage Death". Infection and Immunity 73, nr 9 (wrzesień 2005): 5720–34. http://dx.doi.org/10.1128/iai.73.9.5720-5734.2005.
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ABSTRACT Legionella pneumophila is a motile intracellular pathogen of macrophages and amoebae. When nutrients become scarce, the bacterium induces expression of transmission traits, some of which are dependent on the flagellar sigma factor FliA (σ28). To test how particular components of the L. pneumophila flagellar regulon contribute to virulence, we compared a fliA mutant with strains whose flagellar construction is disrupted at various stages. We find that L. pneumophila requires FliA to avoid lysosomal degradation in murine bone marrow-derived macrophages (BMM), to regulate production of a melanin-like pigment, and to regulate binding to the dye crystal violet, whereas motility, flagellar secretion, and external flagella or flagellin are dispensable for these activities. Thus, in addition to flagellar genes, the FliA sigma factor regulates an effector(s) or regulator(s) that contributes to other transmissive traits, notably inhibition of phagosome maturation. Whether or not the microbes produced flagellin, all nonmotile L. pneumophila mutants bound BMM less efficiently than the wild type, resulting in poor infectivity and a loss of contact-dependent death of BMM. Therefore, bacterial motility increases contact with host cells during infection, but flagellin is not an adhesin. When BMM contact by each nonmotile strain was promoted by centrifugation, all the mutants bound BMM similarly, but only those microbes that synthesized flagellin induced BMM death. Thus, the flagellar regulon equips the aquatic pathogen L. pneumophila to coordinate motility with multiple traits vital to virulence.
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Rompolas, Panteleimon, Ramila S. Patel-King i Stephen M. King. "Association of Lis1 with outer arm dynein is modulated in response to alterations in flagellar motility". Molecular Biology of the Cell 23, nr 18 (15.09.2012): 3554–65. http://dx.doi.org/10.1091/mbc.e12-04-0287.
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The cytoplasmic dynein regulatory factor Lis1, which induces a persistent tight binding to microtubules and allows for transport of cargoes under high-load conditions, is also present in motile cilia/flagella. We observed that Lis1 levels in flagella of Chlamydomonas strains that exhibit defective motility due to mutation of various axonemal substructures were greatly enhanced compared with wild type; this increase was absolutely dependent on the presence within the flagellum of the outer arm dynein α heavy chain/light chain 5 thioredoxin unit. To assess whether cells might interpret defective motility as a “high-load environment,” we reduced the flagellar beat frequency of wild-type cells through enhanced viscous load and by reductive stress; both treatments resulted in increased levels of flagellar Lis1, which altered the intrinsic beat frequency of the trans flagellum. Differential extraction of Lis1 from wild-type and mutant axonemes suggests that the affinity of outer arm dynein for Lis1 is directly modulated. In cytoplasm, Lis1 localized to two punctate structures, one of which was located near the base of the flagella. These data reveal that the cell actively monitors motility and dynamically modulates flagellar levels of the dynein regulatory factor Lis1 in response to imposed alterations in beat parameters.
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Murray, Thomas S., i Barbara I. Kazmierczak. "FlhF Is Required for Swimming and Swarming in Pseudomonas aeruginosa". Journal of Bacteriology 188, nr 19 (1.10.2006): 6995–7004. http://dx.doi.org/10.1128/jb.00790-06.
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ABSTRACT FlhF is a signal recognition particle-like protein present in monotrichous bacteria. The loss of FlhF in various bacteria results in decreased transcription of class II, III, or IV flagellar genes, leads to diminished or absent motility, and results in the assembly of flagella at nonpolar locations on the cell surface. In this work, we demonstrate that the loss of FlhF results in defective swimming and swarming motility of Pseudomonas aeruginosa. The FlhF protein localizes to the flagellar pole; in the absence of FlhF, flagellar assembly occurs but is no longer restricted to the pole. ΔflhF bacteria swim at lower velocities than wild-type bacteria in liquid media and can no longer swarm when assayed under standard swarming conditions (0.5% agar). However, ΔflhF bacteria regain swarming behavior when plated on 0.3% agar. ΔflhF organisms show decreased transcription and expression of flagellin (FliC) both in liquid media and on swarming plates compared to wild-type bacteria. However, changes in flagellin expression do not explain the different motility patterns observed for ΔflhF bacteria. Instead, the aberrant placement of flagella in ΔflhF bacteria may reduce their ability to move this rod-shaped organism effectively.
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Eloe, Emiley A., Federico M. Lauro, Rudi F. Vogel i Douglas H. Bartlett. "The Deep-Sea Bacterium Photobacterium profundum SS9 Utilizes Separate Flagellar Systems for Swimming and Swarming under High-Pressure Conditions". Applied and Environmental Microbiology 74, nr 20 (22.08.2008): 6298–305. http://dx.doi.org/10.1128/aem.01316-08.
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ABSTRACT Motility is a critical function needed for nutrient acquisition, biofilm formation, and the avoidance of harmful chemicals and predators. Flagellar motility is one of the most pressure-sensitive cellular processes in mesophilic bacteria; therefore, it is ecologically relevant to determine how deep-sea microbes have adapted their motility systems for functionality at depth. In this study, the motility of the deep-sea piezophilic bacterium Photobacterium profundum SS9 was investigated and compared with that of the related shallow-water piezosensitive strain Photobacterium profundum 3TCK, as well as that of the well-studied piezosensitive bacterium Escherichia coli. The SS9 genome contains two flagellar gene clusters: a polar flagellum gene cluster (PF) and a putative lateral flagellum gene cluster (LF). In-frame deletions were constructed in the two flagellin genes located within the PF cluster (flaA and flaC), the one flagellin gene located within the LF cluster (flaB), a component of a putative sodium-driven flagellar motor (motA2), and a component of a putative proton-driven flagellar motor (motA1). SS9 PF flaA, flaC, and motA2 mutants were defective in motility under all conditions tested. In contrast, the flaB and motA1 mutants were defective only under conditions of high pressure and high viscosity. flaB and motA1 gene expression was strongly induced by elevated pressure plus increased viscosity. Direct swimming velocity measurements were obtained using a high-pressure microscopic chamber, where increases in pressure resulted in a striking decrease in swimming velocity for E. coli and a gradual reduction for 3TCK which proceeded up to 120 MPa, while SS9 increased swimming velocity at 30 MPa and maintained motility up to a maximum pressure of 150 MPa. Our results indicate that P. profundum SS9 possesses two distinct flagellar systems, both of which have acquired dramatic adaptations for optimal functionality under high-pressure conditions.
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Logan, Susan M. "Flagellar glycosylation – a new component of the motility repertoire?" Microbiology 152, nr 5 (1.05.2006): 1249–62. http://dx.doi.org/10.1099/mic.0.28735-0.
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The biosynthesis, assembly and regulation of the flagellar apparatus has been the subject of extensive studies over many decades, with considerable attention devoted to the peritrichous flagella of Escherichia coli and Salmonella enterica. The characterization of flagellar systems from many other bacterial species has revealed subtle yet distinct differences in composition, regulation and mode of assembly of this important subcellular structure. Glycosylation of the major structural protein, the flagellin, has been shown most recently to be an important component of numerous flagellar systems in both Archaea and Bacteria, playing either an integral role in assembly or for a number of bacterial pathogens a role in virulence. This review focuses on the structural diversity in flagellar glycosylation systems and demonstrates that as a consequence of the unique assembly processes, the type of glycosidic linkage found on archaeal and bacterial flagellins is distinctive.
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Yang, Yong, Deborah A. Cochran, Mary D. Gargano, Iryna King, Nayef K. Samhat, Benjain P. Burger, Katherine R. Sabourin i in. "Regulation of flagellar motility by the conserved flagellar protein CG34110/Ccdc135/FAP50". Molecular Biology of the Cell 22, nr 7 (kwiecień 2011): 976–87. http://dx.doi.org/10.1091/mbc.e10-04-0331.
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Eukaryotic cilia and flagella are vital sensory and motile organelles. The calcium channel PKD2 mediates sensory perception on cilia and flagella, and defects in this can contribute to ciliopathic diseases. Signaling from Pkd2-dependent Ca2+ rise in the cilium to downstream effectors may require intermediary proteins that are largely unknown. To identify these proteins, we carried out genetic screens for mutations affecting Drosophila melanogaster sperm storage, a process mediated by Drosophila Pkd2. Here we show that a new mutation lost boys (lobo) encodes a conserved flagellar protein CG34110, which corresponds to vertebrate Ccdc135 (E = 6e-78) highly expressed in ciliated respiratory epithelia and sperm, and to FAP50 (E = 1e-28) in the Chlamydomonas reinhardtii flagellar proteome. CG34110 localizes along the fly sperm flagellum. FAP50 is tightly associated with the outer doublet microtubules of the axoneme and appears not to be a component of the central pair, radial spokes, dynein arms, or structures defined by the mbo waveform mutants. Phenotypic analyses indicate that both Pkd2 and lobo specifically affect sperm movement into the female storage receptacle. We hypothesize that the CG34110/Ccdc135/FAP50 family of conserved flagellar proteins functions within the axoneme to mediate Pkd2-dependent processes in the sperm flagellum and other motile cilia.
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Amiel, Eyal, Rustin R. Lovewell, George A. O'Toole, Deborah A. Hogan i Brent Berwin. "Pseudomonas aeruginosa Evasion of Phagocytosis Is Mediated by Loss of Swimming Motility and Is Independent of Flagellum Expression". Infection and Immunity 78, nr 7 (10.05.2010): 2937–45. http://dx.doi.org/10.1128/iai.00144-10.
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ABSTRACT Pseudomonas aeruginosa is a pathogenic Gram-negative bacterium that causes severe opportunistic infections in immunocompromised individuals; in particular, severity of infection with P. aeruginosa positively correlates with poor prognosis in cystic fibrosis (CF) patients. Establishment of chronic infection by this pathogen is associated with downregulation of flagellar expression and of other genes that regulate P. aeruginosa motility. The current paradigm is that loss of flagellar expression enables immune evasion by the bacteria due to loss of engagement by phagocytic receptors that recognize flagellar components and loss of immune activation through flagellin-mediated Toll-like receptor (TLR) signaling. In this work, we employ bacterial and mammalian genetic approaches to demonstrate that loss of motility, not the loss of the flagellum per se, is the critical factor in the development of resistance to phagocytosis by P. aeruginosa. We demonstrate that isogenic P. aeruginosa mutants deficient in flagellar function, but retaining an intact flagellum, are highly resistant to phagocytosis by both murine and human phagocytic cells at levels comparable to those of flagellum-deficient mutants. Furthermore, we show that loss of MyD88 signaling in murine phagocytes does not recapitulate the phagocytic deficit observed for either flagellum-deficient or motility-deficient P. aeruginosa mutants. Our data demonstrate that loss of bacterial motility confers a dramatic resistance to phagocytosis that is independent of both flagellar expression and TLR signaling. These findings provide an explanation for the well-documented observation of nonmotility in clinical P. aeruginosa isolates and for how this phenotype confers upon the bacteria an advantage in the context of immune evasion.
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Tomich, Mladen, Christine A. Herfst, Joseph W. Golden i Christian D. Mohr. "Role of Flagella in Host Cell Invasion by Burkholderia cepacia". Infection and Immunity 70, nr 4 (kwiecień 2002): 1799–806. http://dx.doi.org/10.1128/iai.70.4.1799-1806.2002.
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ABSTRACT Burkholderia cepacia is an important opportunistic human pathogen that affects immunocompromised individuals, particularly cystic fibrosis (CF) patients. Colonization of the lungs of a CF patient by B. cepacia can lead not only to a decline in respiratory function but also to an acute systemic infection, such as bacteremia. We have previously demonstrated that a CF clinical isolate of B. cepacia, strain J2315, can invade and survive within cultured respiratory epithelial cells. In order to further characterize the mechanisms of invasion of B. cepacia, we screened a transposon-generated mutant library of strain J2315 for mutants defective in invasion of A549 respiratory epithelial cells. Here we describe isolation and characterization of a nonmotile mutant of B. cepacia with reduced invasiveness due to disruption of fliG, which encodes a component of the motor-switch complex of the flagellar basal body. We also found that a defined null mutation in fliI, a gene encoding a highly conserved ATPase required for protein translocation via the flagellar type III secretion system, also resulted in loss of motility and a significant reduction in invasion. Both mutants lacked detectable intracellular flagellin and failed to export detectable amounts of flagellin into culture supernatants, suggesting that disruption of fliG and fliI impaired flagellar biogenesis. The reduction in invasion did not appear to be due to defective adherence of the flagellar mutants to A549 cells, suggesting that functional flagella and motility are required for full invasiveness of B. cepacia. Our findings indicate that flagellum-mediated motility may facilitate penetration of host epithelial barriers by B. cepacia, contributing to establishment of infection and systemic spread of the organism.
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Lane, M. Chelsea, Virginia Lockatell, Greta Monterosso, Daniel Lamphier, Julia Weinert, J. Richard Hebel, David E. Johnson i Harry L. T. Mobley. "Role of Motility in the Colonization of Uropathogenic Escherichia coli in the Urinary Tract". Infection and Immunity 73, nr 11 (listopad 2005): 7644–56. http://dx.doi.org/10.1128/iai.73.11.7644-7656.2005.
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ABSTRACT Uropathogenic Escherichia coli (UPEC) causes most uncomplicated urinary tract infections (UTIs) in humans. Flagellum-mediated motility and chemotaxis have been suggested to contribute to virulence by enabling UPEC to escape host immune responses and disperse to new sites within the urinary tract. To evaluate their contribution to virulence, six separate flagellar mutations were constructed in UPEC strain CFT073. The mutants constructed were shown to have four different flagellar phenotypes: fliA and fliC mutants do not produce flagella; the flgM mutant has similar levels of extracellular flagellin as the wild type but exhibits less motility than the wild type; the motAB mutant is nonmotile; and the cheW and cheY mutants are motile but nonchemotactic. Virulence was assessed by transurethral independent challenges and cochallenges of CBA mice with the wild type and each mutant. CFU/ml of urine or CFU/g bladder or kidney was determined 3 days postinoculation for the independent challenges and at 6, 16, 48, 60, and 72 h postinoculation for the cochallenges. While these mutants colonized the urinary tract during independent challenge, each of the mutants was outcompeted by the wild-type strain to various degrees at specific time points during cochallenge. Altogether, these results suggest that flagella and flagellum-mediated motility/chemotaxis may not be absolutely required for virulence but that these traits contribute to the fitness of UPEC and therefore significantly enhance the pathogenesis of UTIs caused by UPEC.
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Ghelardi, Emilia, Francesco Celandroni, Sara Salvetti, Douglas J. Beecher, Myriam Gominet, Didier Lereclus, Amy C. L. Wong i Sonia Senesi. "Requirement of flhA for Swarming Differentiation, Flagellin Export, and Secretion of Virulence-Associated Proteins in Bacillus thuringiensis". Journal of Bacteriology 184, nr 23 (1.12.2002): 6424–33. http://dx.doi.org/10.1128/jb.184.23.6424-6433.2002.
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ABSTRACT Bacillus thuringiensis is being used worldwide as a biopesticide, although increasing evidence suggests that it is emerging as an opportunistic human pathogen. While phospholipases, hemolysins, and enterotoxins are claimed to be responsible for B. thuringiensis virulence, there is no direct evidence to indicate that the flagellum-driven motility plays a role in parasite-host interactions. This report describes the characterization of a mini-Tn10 mutant of B. thuringiensis that is defective in flagellum filament assembly and in swimming and swarming motility as well as in the production of hemolysin BL and phosphatidylcholine-preferring phospholipase C. The mutant strain was determined to carry the transposon insertion in flhA, a flagellar class II gene encoding a protein of the flagellar type III export apparatus. Interestingly, the flhA mutant of B. thuringiensis synthesized flagellin but was impaired in flagellin export. Moreover, a protein similar to the anti-sigma factor FlgM that acts in regulating flagellar class III gene transcription was not detectable in B. thuringiensis, thus suggesting that the flagellar gene expression hierarchy of B. thuringiensis differs from that described for Bacillus subtilis. The flhA mutant of B. thuringiensis was also defective in the secretion of hemolysin BL and phosphatidylcholine-preferring phospholipase C, although both of these virulence factors were synthesized by the mutant. Since complementation of the mutant with a plasmid harboring the flhA gene restored swimming and swarming motility as well as secretion of toxins, the overall results indicate that motility and virulence in B. thuringiensis may be coordinately regulated by flhA, which appears to play a crucial role in the export of flagellar as well as nonflagellar proteins.
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Sal, Melanie S., Chunhao Li, M. A. Motalab, Satoshi Shibata, Shin-Ichi Aizawa i Nyles W. Charon. "Borrelia burgdorferi Uniquely Regulates Its Motility Genes and Has an Intricate Flagellar Hook-Basal Body Structure". Journal of Bacteriology 190, nr 6 (11.01.2008): 1912–21. http://dx.doi.org/10.1128/jb.01421-07.
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ABSTRACT Borrelia burgdorferi is a flat-wave, motile spirochete that causes Lyme disease. Motility is provided by periplasmic flagella (PFs) located between the cell cylinder and an outer membrane sheath. The structure of these PFs, which are composed of a basal body, a hook, and a filament, is similar to the structure of flagella of other bacteria. To determine if hook formation influences flagellin gene transcription in B. burgdorferi, we inactivated the hook structural gene flgE by targeted mutagenesis. In many bacteria, completion of the hook structure serves as a checkpoint for transcriptional control of flagellum synthesis and other chemotaxis and motility genes. Specifically, the hook allows secretion of the anti-sigma factor FlgM and concomitant late gene transcription promoted by σ28. However, the control of B. burgdorferi PF synthesis differs from the control of flagellum synthesis in other bacteria; the gene encoding σ28 is not present in the genome of B. burgdorferi, nor are any σ28 promoter recognition sequences associated with the motility genes. We found that B. burgdorferi flgE mutants lacked PFs, were rod shaped, and were nonmotile, which substantiates previous evidence that PFs are involved in both cell morphology and motility. Although most motility and chemotaxis gene products accumulated at wild-type levels in the absence of FlgE, mutant cells had markedly decreased levels of the flagellar filament proteins FlaA and FlaB. Further analyses showed that the reduction in the levels of flagellin proteins in the spirochetes lacking FlgE was mediated at the posttranscriptional level. Taken together, our results indicate that in B. burgdorferi, the completion of the hook does not serve as a checkpoint for transcriptional regulation of flagellum synthesis. In addition, we also present evidence that the hook protein in B. burgdorferi forms a high-molecular-weight complex and that formation of this complex occurs in the periplasmic space.
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Thomas, Nikhil A., i Ken F. Jarrell. "Characterization of Flagellum Gene Families of Methanogenic Archaea and Localization of Novel Flagellum Accessory Proteins". Journal of Bacteriology 183, nr 24 (15.12.2001): 7154–64. http://dx.doi.org/10.1128/jb.183.24.7154-7164.2001.
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ABSTRACT Archaeal flagella are unique motility structures, and the absence of bacterial structural motility genes in the complete genome sequences of flagellated archaeal species suggests that archaeal flagellar biogenesis is likely mediated by novel components. In this study, a conserved flagellar gene family from each of Methanococcus voltae, Methanococcus maripaludis,Methanococcus thermolithotrophicus, andMethanococcus jannaschii has been characterized. These species possess multiple flagellin genes followed immediately by eight known and supposed flagellar accessory genes,flaCDEFGHIJ. Sequence analyses identified a conserved Walker box A motif in the putative nucleotide binding proteins FlaH and FlaI that may be involved in energy production for flagellin secretion or assembly. Northern blotting studies demonstrated that all the species have abundant polycistronic mRNAs corresponding to some of the structural flagellin genes, and in some cases several flagellar accessory genes were shown to be cotranscribed with the flagellin genes. Cloned flagellar accessory genes of M. voltaewere successfully overexpressed as His-tagged proteins inEscherichia coli. These recombinant flagellar accessory proteins were affinity purified and used as antigens to raise polyclonal antibodies for localization studies. Immunoblotting of fractionated M. voltae cells demonstrated that FlaC, FlaD, FlaE, FlaH, and FlaI are all present in the cell as membrane-associated proteins but are not major components of isolated flagellar filaments. Interestingly, flaD was found to encode two proteins, each translated from a separate ribosome binding site. These protein expression data indicate for the first time that the putative flagellar accessory genes of M. voltae, and likely those of other archaeal species, do encode proteins that can be detected in the cell.
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Morris, David C., Fen Peng, Jeffrey R. Barker i Karl E. Klose. "Lipidation of an FlrC-Dependent Protein Is Required for Enhanced Intestinal Colonization by Vibrio cholerae". Journal of Bacteriology 190, nr 1 (2.11.2007): 231–39. http://dx.doi.org/10.1128/jb.00924-07.
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ABSTRACT Vibrio cholerae, the causative agent of cholera, has a sheathed, polar flagellum, and motility has been linked to virulence. An operon with two genes, flgO and flgP (VC2207 and VC2206), is positively regulated by FlrC, the activator of class III flagellar genes. Deletion of flgP results in a nonmotile phenotype, demonstrating the requirement of this gene for V. cholerae motility. V. cholerae ΔflgP cells synthesize fragile and defective flagella but transcribe flagellar genes similar to the wild-type strain. PhoA fusion analysis indicated that the putative lipoprotein FlgP is localized external to the cytoplasm, and fractionation demonstrated that it was localized to the outer membrane. Mutagenesis of the site of lipidation of FlgP (C18G) prevented [3H]palmitate incorporation and outer membrane localization. Interestingly, FlgP with the mutation C18G [FlgP(C18G)] could complement the ΔflgP mutant for motility, and the cells synthesized wild-type flagella. The ΔflgP mutant strain was defective for intestinal colonization (∼20-fold), but FlgP(C18G) was unable to complement this defect, demonstrating that lipidation of FlgP is essential for its role in intestinal colonization but not flagellar synthesis. FlgP thus represents a novel V. cholerae intestinal colonization factor that is regulated by the flagellar transcription hierarchy.
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Oda, Toshiyuki, Haruaki Yanagisawa, Toshiki Yagi i Masahide Kikkawa. "Mechanosignaling between central apparatus and radial spokes controls axonemal dynein activity". Journal of Cell Biology 204, nr 5 (3.03.2014): 807–19. http://dx.doi.org/10.1083/jcb.201312014.
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Cilia/flagella are conserved organelles that generate fluid flow in eukaryotes. The bending motion of flagella requires concerted activity of dynein motors. Although it has been reported that the central pair apparatus (CP) and radial spokes (RSs) are important for flagellar motility, the molecular mechanism underlying CP- and RS-mediated dynein regulation has not been identified. In this paper, we identified nonspecific intermolecular collision between CP and RS as one of the regulatory mechanisms for flagellar motility. By combining cryoelectron tomography and motility analyses of Chlamydomonas reinhardtii flagella, we show that binding of streptavidin to RS heads paralyzed flagella. Moreover, the motility defect in a CP projection mutant could be rescued by the addition of exogenous protein tags on RS heads. Genetic experiments demonstrated that outer dynein arms are the major downstream effectors of CP- and RS-mediated regulation of flagellar motility. These results suggest that mechanosignaling between CP and RS regulates dynein activity in eukaryotic flagella.
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Elhadad, Dana, Prerak Desai, Galia Rahav, Michael McClelland i Ohad Gal-Mor. "Flagellin Is Required for Host Cell Invasion and Normal Salmonella Pathogenicity Island 1 Expression by Salmonella enterica Serovar Paratyphi A". Infection and Immunity 83, nr 9 (8.06.2015): 3355–68. http://dx.doi.org/10.1128/iai.00468-15.
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Salmonella entericaserovar Paratyphi A is a human-specific serovar that, together withSalmonella entericaserovar Typhi andSalmonella entericaserovar Sendai, causes enteric fever. Unlike the nontyphoidalSalmonella entericaserovar Typhimurium, the genomes ofS. Typhi andS. Paratyphi A are characterized by inactivation of multiple genes, including in the flagellum-chemotaxis pathway. Here, we explored the motility phenotype ofS. Paratyphi A and the role of flagellin in key virulence-associated phenotypes. Motility studies established that the human-adapted typhoidalS. Typhi,S. Paratyphi A, andS. Sendai are all noticeably less motile thanS. Typhimurium, and comparative transcriptome sequencing (RNA-Seq) showed that inS. Paratyphi A, the entire motility-chemotaxis regulon is expressed at significantly lowers levels than inS. Typhimurium. Nevertheless,S. Paratyphi A, likeS. Typhimurium, requires a functional flagellum for epithelial cell invasion and macrophage uptake, probably in a motility-independent mechanism. In contrast, flagella were found to be dispensable for host cell adhesion. Moreover, we demonstrate that inS. Paratyphi A, but not inS. Typhimurium, the lack of flagellin results in increased transcription of the flagellar and theSalmonellapathogenicity island 1 (SPI-1) regulons in a FliZ-dependent manner and in oversecretion of SPI-1 effectors via type three secretion system 1. Collectively, these results suggest a novel regulatory linkage between flagellin and SPI-1 inS. Paratyphi A that does not occur inS. Typhimurium and demonstrate curious distinctions in motility and the expression of the flagellum-chemotaxis regulon between these clinically relevant pathogens.
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Parthasarathy, G., Y. Yao i K. S. Kim. "Flagella Promote Escherichia coli K1 Association with and Invasion of Human Brain Microvascular Endothelial Cells". Infection and Immunity 75, nr 6 (19.03.2007): 2937–45. http://dx.doi.org/10.1128/iai.01543-06.
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ABSTRACT Escherichia coli containing the K1 capsule is the leading cause of gram-negative meningitis, but the pathogenesis of this disease is not completely understood. Recent microarray experiments in which we compared the gene expression profile of E. coli K1 associated with human brain microvascular endothelial cells (HBMEC) to the gene expression profile of E. coli K1 not associated with HBMEC revealed that there was a threefold increase in the expression of the fliI gene, encoding an ATP synthase involved in flagellar synthesis and motility, in HBMEC-associated E. coli. In this study, we examined the role of flagella in E. coli K1 association with and invasion of HBMEC by constructing isogenic ΔflhDC, ΔfliI, ΔfliC, and ΔcheW mutants that represented each class of flagellar genes. Mutations that affected the flagellum structure and flagellum formation (ΔflhDC, ΔfliI, and ΔfliC) resulted in significant defects in motility, as well as in HBMEC association and invasion, compared to the characteristics of the wild-type strain when preparations were examined with or without centrifugation. Transcomplementation with the corresponding genes restored the levels of these mutants to the levels of the parent strain. These findings suggest that the HBMEC association and invasion defects of the mutants are most likely related to flagella and less likely due to their motility defects. This conclusion was supported by our demonstration that the cheW mutant was not motile but was able to associate with and invade HBMEC. In addition, purified recombinant flagellin reduced the association of the wild-type strain with HBMEC by ∼40%, while it had no effect on the fliC mutant's association with HBMEC. Together, these findings indicate that flagella promote E. coli K1 binding to HBMEC.
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Nguyen, HoangKim T., Jaspreet Sandhu, Gerasimos Langousis i Kent L. Hill. "CMF22 Is a Broadly Conserved Axonemal Protein and Is Required for Propulsive Motility in Trypanosoma brucei". Eukaryotic Cell 12, nr 9 (12.07.2013): 1202–13. http://dx.doi.org/10.1128/ec.00068-13.
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ABSTRACT The eukaryotic flagellum (or cilium) is a broadly conserved organelle that provides motility for many pathogenic protozoa and is critical for normal development and physiology in humans. Therefore, defining core components of motile axonemes enhances understanding of eukaryotic biology and provides insight into mechanisms of inherited and infectious diseases in humans. In this study, we show that component of motile flagella 22 (CMF22) is tightly associated with the flagellar axoneme and is likely to have been present in the last eukaryotic common ancestor. The CMF22 amino acid sequence contains predicted IQ and A TPase a ssociated with a variety of cellular a ctivities (AAA) motifs that are conserved among CMF22 orthologues in diverse organisms, hinting at the importance of these domains in CMF22 function. Knockdown by RNA interference (RNAi) and rescue with an RNAi-immune mRNA demonstrated that CMF22 is required for propulsive cell motility in Trypanosoma brucei . Loss of propulsive motility in CMF22-knockdown cells was due to altered flagellar beating patterns, rather than flagellar paralysis, indicating that CMF22 is essential for motility regulation and likely functions as a fundamental regulatory component of motile axonemes. CMF22 association with the axoneme is weakened in mutants that disrupt the nexin-dynein regulatory complex, suggesting potential interaction with this complex. Our results provide insight into the core machinery required for motility of eukaryotic flagella.
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Akahoshi, Douglas T., Dean E. Natwick, Weirong Yuan, Wuyuan Lu, Sean R. Collins i Charles L. Bevins. "Flagella-driven motility is a target of human Paneth cell defensin activity". PLOS Pathogens 19, nr 2 (23.02.2023): e1011200. http://dx.doi.org/10.1371/journal.ppat.1011200.
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In the mammalian intestine, flagellar motility can provide microbes competitive advantage, but also threatens the spatial segregation established by the host at the epithelial surface. Unlike microbicidal defensins, previous studies indicated that the protective activities of human α-defensin 6 (HD6), a peptide secreted by Paneth cells of the small intestine, resides in its remarkable ability to bind microbial surface proteins and self-assemble into protective fibers and nets. Given its ability to bind flagellin, we proposed that HD6 might be an effective inhibitor of bacterial motility. Here, we utilized advanced automated live cell fluorescence imaging to assess the effects of HD6 on actively swimming Salmonella enterica in real time. We found that HD6 was able to effectively restrict flagellar motility of individual bacteria. Flagellin-specific antibody, a classic inhibitor of flagellar motility that utilizes a mechanism of agglutination, lost its activity at low bacterial densities, whereas HD6 activity was not diminished. A single amino acid variant of HD6 that was able to bind flagellin, but not self-assemble, lost ability to inhibit flagellar motility. Together, these results suggest a specialized role of HD6 self-assembly into polymers in targeting and restricting flagellar motility.
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Wang, Hongou, Zhiheng Tang, Baoshuai Xue, Qinghui Lu, Xiaoyun Liu i Qinghua Zou. "Salmonella Regulator STM0347 Mediates Flagellar Phase Variation via Hin Invertase". International Journal of Molecular Sciences 23, nr 15 (30.07.2022): 8481. http://dx.doi.org/10.3390/ijms23158481.
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Salmonella enterica is one of the most important food-borne pathogens, whose motility and virulence are highly related to flagella. Flagella alternatively express two kinds of surface antigen flagellin, FliC and FljB, in a phenomenon known as flagellar phase variation. The molecular mechanisms by which the switching orientation of the Hin-composed DNA segment mediates the expression of the fljBA promoter have been thoroughly illustrated. However, the precise regulators that control DNA strand exchange are barely understood. In this study, we found that a putative response regulator, STM0347, contributed to the phase variation of flagellin in S. Typhimurium. With quantitative proteomics and secretome profiling, a lack of STM0347 was confirmed to induce the transformation of flagellin from FliC to FljB. Real-time PCR and in vitro incubation of SMT0347 with the hin DNA segment suggested that STM0347 disturbed Hin-catalyzed DNA reversion via hin degradation, and the overexpression of Hin was sufficient to elicit flagellin variation. Subsequently, the Δstm0347 strain was outcompeted by its parental strain in HeLa cell invasion. Collectively, our results reveal the crucial role of STM0347 in Salmonella virulence and flagellar phase variation and highlight the complexity of the regulatory network of Hin-modulated flagellum phase variation in Salmonella.
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Sterzenbach, Torsten, Lucie Bartonickova, Wiebke Behrens, Birgit Brenneke, Jessika Schulze, Friederike Kops, Elaine Y. Chin i in. "Role of the Helicobacter hepaticus Flagellar Sigma Factor FliA in Gene Regulation and Murine Colonization". Journal of Bacteriology 190, nr 19 (8.08.2008): 6398–408. http://dx.doi.org/10.1128/jb.00626-08.
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ABSTRACT The enterohepatic Helicobacter species Helicobacter hepaticus colonizes the murine intestinal and hepatobiliary tract and is associated with chronic intestinal inflammation, gall stone formation, hepatitis, and hepatocellular carcinoma. Thus far, the role of H. hepaticus motility and flagella in intestinal colonization is unknown. In other, closely related bacteria, late flagellar genes are mainly regulated by the sigma factor FliA (σ28). We investigated the function of the H. hepaticus FliA in gene regulation, flagellar biosynthesis, motility, and murine colonization. Competitive microarray analysis of the wild type versus an isogenic fliA mutant revealed that 11 genes were significantly more highly expressed in wild-type bacteria and 2 genes were significantly more highly expressed in the fliA mutant. Most of these were flagellar genes, but four novel FliA-regulated genes of unknown function were identified. H. hepaticus possesses two identical copies of the gene encoding the FliA-dependent major flagellin subunit FlaA (open reading frames HH1364 and HH1653). We characterized the phenotypes of mutants in which fliA or one or both copies of the flaA gene were knocked out. flaA_1 flaA_2 double mutants and fliA mutants did not synthesize detectable amounts of FlaA and possessed severely truncated flagella. Also, both mutants were nonmotile and unable to colonize mice. Mutants with either flaA gene knocked out produced flagella morphologically similar to those of wild-type bacteria and expressed FlaA and FlaB. flaA_1 mutants which had flagella but displayed reduced motility did not colonize mice, indicating that motility is required for intestinal colonization by H. hepaticus and that the presence of flagella alone is not sufficient.
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Bouteiller, Mathilde, Charly Dupont, Yvann Bourigault, Xavier Latour, Corinne Barbey, Yoan Konto-Ghiorghi i Annabelle Merieau. "Pseudomonas Flagella: Generalities and Specificities". International Journal of Molecular Sciences 22, nr 7 (24.03.2021): 3337. http://dx.doi.org/10.3390/ijms22073337.
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Flagella-driven motility is an important trait for bacterial colonization and virulence. Flagella rotate and propel bacteria in liquid or semi-liquid media to ensure such bacterial fitness. Bacterial flagella are composed of three parts: a membrane complex, a flexible-hook, and a flagellin filament. The most widely studied models in terms of the flagellar apparatus are E. coli and Salmonella. However, there are many differences between these enteric bacteria and the bacteria of the Pseudomonas genus. Enteric bacteria possess peritrichous flagella, in contrast to Pseudomonads, which possess polar flagella. In addition, flagellar gene expression in Pseudomonas is under a four-tiered regulatory circuit, whereas enteric bacteria express flagellar genes in a three-step manner. Here, we use knowledge of E. coli and Salmonella flagella to describe the general properties of flagella and then focus on the specificities of Pseudomonas flagella. After a description of flagellar structure, which is highly conserved among Gram-negative bacteria, we focus on the steps of flagellar assembly that differ between enteric and polar-flagellated bacteria. In addition, we summarize generalities concerning the fuel used for the production and rotation of the flagellar macromolecular complex. The last part summarizes known regulatory pathways and potential links with the type-six secretion system (T6SS).
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Drake, David, i Thomas C. Montie. "Protection against Pseudomonas aeruginosa infection by passive transfer of anti-flagellar serum". Canadian Journal of Microbiology 33, nr 9 (1.09.1987): 755–63. http://dx.doi.org/10.1139/m87-130.
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The specificity of adsorbed flagellar antisera for H-antigen was demonstrated in vitro by cross-agglutination assays, motility inhibition, and an ELISA. The specific flagellar antibody was determined to be an IgG. Complete protection against burn wound sepsis was achieved with flagellar antisera. Cross-protection experiments revealed that protection was not only H-antigen dependent, but specific for the flagella antigen type. Antiserum raised against b-type flagella would only protect against homologous bacterial challenge and not against a-type flagellated strains. Results using a-type antisera were consistent, giving protection only against the homologous strain. In contrast, protective capacity was selectively removed from antisera by adsorbing with Fla+ cells. Bacteria colonized the burn wounds of passively protected mice to similar levels as seen in nonprotected animals, but the colonization remained localized and did not result in systemic infection, a pattern similar to infections with motility mutants observed in other studies. Animals rendered neutropenic prior to burning were not protected with flagellar antisera. These data suggested a role for phagocytic cells in protection. Immobilization by flagellar antiserum was observed both by microscopic studies and by inhibition of colony spreading. Antiflagellar antibody is hypothesized as exerting its protective capacity possibly in two ways; first by inhibiting the motility of invading bacteria by binding to the flagellum and immobilizing the bacteria, and secondly by acting as an opsonin, targeting either immobilized or mobile cells for phagocytosis.
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Braun, Tatjana, Matthijn R. Vos, Nir Kalisman, Nicholas E. Sherman, Reinhard Rachel, Reinhard Wirth, Gunnar F. Schröder i Edward H. Egelman. "Archaeal flagellin combines a bacterial type IV pilin domain with an Ig-like domain". Proceedings of the National Academy of Sciences 113, nr 37 (30.08.2016): 10352–57. http://dx.doi.org/10.1073/pnas.1607756113.
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The bacterial flagellar apparatus, which involves ∼40 different proteins, has been a model system for understanding motility and chemotaxis. The bacterial flagellar filament, largely composed of a single protein, flagellin, has been a model for understanding protein assembly. This system has no homology to the eukaryotic flagellum, in which the filament alone, composed of a microtubule-based axoneme, contains more than 400 different proteins. The archaeal flagellar system is simpler still, in some cases having ∼13 different proteins with a single flagellar filament protein. The archaeal flagellar system has no homology to the bacterial one and must have arisen by convergent evolution. However, it has been understood that the N-terminal domain of the archaeal flagellin is a homolog of the N-terminal domain of bacterial type IV pilin, showing once again how proteins can be repurposed in evolution for different functions. Using cryo-EM, we have been able to generate a nearly complete atomic model for a flagellar-like filament of the archaeon Ignicoccus hospitalis from a reconstruction at ∼4-Å resolution. We can now show that the archaeal flagellar filament contains a β-sandwich, previously seen in the FlaF protein that forms the anchor for the archaeal flagellar filament. In contrast to the bacterial flagellar filament, where the outer globular domains make no contact with each other and are not necessary for either assembly or motility, the archaeal flagellin outer domains make extensive contacts with each other that largely determine the interesting mechanical properties of these filaments, allowing these filaments to flex.
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Malamud, Florencia, Pablo S. Torres, Roxana Roeschlin, Luciano A. Rigano, Ramón Enrique, Hernán R. Bonomi, Atilio P. Castagnaro, María Rosa Marano i Adrián A. Vojnov. "The Xanthomonas axonopodis pv. citri flagellum is required for mature biofilm and canker development". Microbiology 157, nr 3 (1.03.2011): 819–29. http://dx.doi.org/10.1099/mic.0.044255-0.
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Xanthomonas axonopodis pv. citri (Xac) is the causative agent of citrus canker. This bacterium develops a characteristic biofilm on both biotic and abiotic surfaces. To evaluate the participation of the single flagellum of Xac in biofilm formation, mutants in the fliC (flagellin) and the flgE (hook) genes were generated. Swimming motility, assessed on 0.25 % agar plates, was markedly reduced in fliC and flgE mutants. However, the fliC and flgE mutants exhibited a flagellar-independent surface translocation on 0.5 % agar plates. Mutation of either the rpfF or the rpfC gene, which both encode proteins involved in cell–cell signalling mediated by diffusible signal factor (DSF), led to a reduction in both flagellar-dependent and flagellar-independent surface translocation, indicating a regulatory role for DSF in both types of motility. Confocal laser scanning microscopy of biofilms produced in static culture demonstrated that the flagellum is also involved in the formation of mushroom-shaped structures and water channels, and in the dispersion of biofilms. The presence of the flagellum was required for mature biofilm development on lemon leaf surfaces. The absence of flagellin produced a slight reduction in Xac pathogenicity and this reduction was more severe when the complete flagellum structure was absent.
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Kirov, Sylvia M., Bronwen C. Tassell, Annalese B. T. Semmler, Lisa A. O’Donovan, Ali A. Rabaan i Jonathan G. Shaw. "Lateral Flagella and Swarming Motility in Aeromonas Species". Journal of Bacteriology 184, nr 2 (15.01.2002): 547–55. http://dx.doi.org/10.1128/jb.184.2.547-555.2002.
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ABSTRACT Swarming motility, a flagellum-dependent behavior that allows bacteria to move over solid surfaces, has been implicated in biofilm formation and bacterial virulence. In this study, light and electron microscopic analyses and genetic and functional investigations have shown that at least 50% of Aeromonas isolates from the species most commonly associated with diarrheal illness produce lateral flagella which mediate swarming motility. Aeromonas lateral flagella were optimally produced when bacteria were grown on solid medium for ≈8 h. Transmission and thin-section electron microscopy confirmed that these flagella do not possess a sheath structure. Southern analysis of Aeromonas reference strains and strains of mesophilic species (n = 84, varied sources and geographic regions) with a probe designed to detect lateral flagellin genes (lafA1 and lafA2) showed there was no marked species association of laf distribution. Approximately 50% of these strains hybridized strongly with the probe, in good agreement with the expression studies. We established a reproducible swarming assay (0.5% Eiken agar in Difco broth, 30°C) for Aeromonas spp. The laf-positive strains exhibited vigorous swarming motility, whereas laf-negative strains grew but showed no movement from the inoculation site. Light and scanning electron microscopic investigations revealed that lateral flagella formed bacterium-bacterium linkages on the agar surface. Strains of an Aeromonas caviae isolate in which lateral flagellum expression was abrogated by specific mutations in flagellar genes did not swarm, proving conclusively that lateral flagella are required for the surface movement. Whether lateral flagella and swarming motility contribute to Aeromonas intestinal colonization and virulence remains to be determined.
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Li, Chunhao, Melanie Sal, Michael Marko i Nyles W. Charon. "Differential Regulation of the Multiple Flagellins in Spirochetes". Journal of Bacteriology 192, nr 10 (19.03.2010): 2596–603. http://dx.doi.org/10.1128/jb.01502-09.
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ABSTRACT The expression of flagellin genes in most bacteria is typically regulated by the flagellum-specific sigma28 factor FliA, and an anti-sigma28 factor, FlgM. However, the regulatory hierarchy in several bacteria that have multiple flagellins is more complex. In these bacteria, the flagellin genes are often transcribed by at least two different sigma factors. The flagellar filament in spirochetes consists of one to three FlaB core proteins and at least one FlaA sheath protein. Here, the genetically amenable bacterium Brachyspira hyodysenteriae was used as a model spirochete to investigate the regulation of its four flagellin genes, flaA, flaB1, flaB2, and flaB3. We found that the flaB1 and flaB2 genes are regulated by sigma28, whereas the flaA and flaB3 genes are controlled by sigma70. The analysis of a flagellar motor switch fliG mutant further supported this proposition; in the mutant, the transcription of flaB1 and flaB2 was inhibited, but that of flaA and flaB3 was not. In addition, the continued expression of flaA and flaB3 in the mutant resulted in the formation of incomplete flagellar filaments that were hollow tubes and consisted primarily of FlaA. Finally, our recent studies have shown that each flagellin unit contributes to the stiffness of the periplasmic flagella, and this stiffness directly correlates with motility. The regulatory mechanism identified here should allow spirochetes to change the relative ratio of these flagellin proteins and, concomitantly, vary the stiffness of their flagellar filament.
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Ballesteros-Rodea, G., M. Santillán, S. Martínez-Calvillo i R. Manning-Cela. "Flagellar Motility ofTrypanosoma cruziEpimastigotes". Journal of Biomedicine and Biotechnology 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/520380.
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The hemoflagellateTrypanosoma cruziis the causative agent of American trypanosomiasis. Despite the importance of motility in the parasite life cycle, little is known aboutT. cruzimotility, and there is no quantitative description of its flagellar beating. Using video microscopy and quantitative vectorial analysis of epimastigote trajectories, we find a forward parasite motility defined by tip-to-base symmetrical flagellar beats. This motion is occasionally interrupted by base-to-tip highly asymmetric beats, which represent the ciliary beat of trypanosomatid flagella. The switch between flagellar and ciliary beating facilitates the parasite's reorientation, which produces a large variability of movement and trajectories that results in different distance ranges traveled by the cells. An analysis of the distance, speed, and rotational angle indicates that epimastigote movement is not completely random, and the phenomenon is highly dependent on the parasite behavior and is characterized by directed and tumbling parasite motion as well as their combination, resulting in the alternation of rectilinear and intricate motility paths.
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Muir, Rachel E., i James W. Gober. "Role of Integration Host Factor in the Transcriptional Activation of Flagellar Gene Expression in Caulobacter crescentus". Journal of Bacteriology 187, nr 3 (1.02.2005): 949–60. http://dx.doi.org/10.1128/jb.187.3.949-960.2005.
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ABSTRACT In the Caulobacter crescentus predivisional cell, class III and IV flagellar genes, encoding the extracytoplasmic components of the flagellum, are transcribed in the nascent swarmer compartment. This asymmetric expression pattern is attributable to the compartmentalized activity of the σ54-dependent transcriptional activator FlbD. Additionally, these temporally transcribed flagellar promoters possess a consensus sequence for the DNA-binding protein integration host factor (IHF), located between the upstream FlbD binding site and the promoter sequences. Here, we deleted the C. crescentus gene encoding the β-subunit of the IHF, ihfB (himD), and examined the effect on flagellar gene expression. The ΔihfB strain exhibited a mild defect in cell morphology and impaired motility. Using flagellar promoter reporter fusions, we observed that expression levels of a subset of class III flagellar promoters were decreased by the loss of IHF. However, one of these promoters, fliK-lacZ, exhibited a wild-type cell cycle-regulated pattern of expression in the absence of IHF. Thus, IHF is required for maximal transcription of several late flagellar genes. The ΔihfB strain was found to express significantly reduced amounts of the class IV flagellin, FljL, as a consequence of reduced transcriptional activity. Our results indicate that the motility defect exhibited by the ΔihfB strain is most likely attributable to its failure to accumulate the class IV-encoded 27-kDa flagellin subunit, FljL.
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Bansil, Rama, Maira A. Constantino, Clover Su-Arcaro, Wentian Liao, Zeli Shen i James G. Fox. "Motility of Different Gastric Helicobacter spp." Microorganisms 11, nr 3 (1.03.2023): 634. http://dx.doi.org/10.3390/microorganisms11030634.
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Helicobacter spp., including the well-known human gastric pathogen H. pylori, can cause gastric diseases in humans and other mammals. They are Gram-negative bacteria that colonize the gastric epithelium and use their multiple flagella to move across the protective gastric mucus layer. The flagella of different Helicobacter spp. vary in their location and number. This review focuses on the swimming characteristics of different species with different flagellar architectures and cell shapes. All Helicobacter spp. use a run-reverse-reorient mechanism to swim in aqueous solutions, as well as in gastric mucin. Comparisons of different strains and mutants of H. pylori varying in cell shape and the number of flagella show that their swimming speed increases with an increasing number of flagella and is somewhat enhanced with a helical cell body shape. The swimming mechanism of H. suis, which has bipolar flagella, is more complex than that of unipolar H. pylori. H. suis exhibits multiple modes of flagellar orientation while swimming. The pH-dependent viscosity and gelation of gastric mucin significantly impact the motility of Helicobacter spp. In the absence of urea, these bacteria do not swim in mucin gel at pH < 4, even though their flagellar bundle rotates.
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Verma, Amrisha, Shiwani K. Arora, Sudha K. Kuravi i Reuben Ramphal. "Roles of Specific Amino Acids in the N Terminus of Pseudomonas aeruginosa Flagellin and of Flagellin Glycosylation in the Innate Immune Response". Infection and Immunity 73, nr 12 (grudzień 2005): 8237–46. http://dx.doi.org/10.1128/iai.73.12.8237-8246.2005.
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ABSTRACT The Toll-like receptor 5 (TLR5) binding site has been predicted to be in the N terminus of the flagellin molecule. In order to better define the interaction between the N-terminal amino acids of Pseudomonas aeruginosa flagellin and TLR5, site-specific mutations were generated between residues 88 and 97 of P. aeruginosa PAK flagellin as well as outside of this region. The mutant flagellins were expressed in Escherichia coli BL21(plysS), purified by affinity chromatography, and passed through a polymyxin B column to remove contaminating lipopolysaccharide (LPS). Their ability to stimulate interleukin-8 (IL-8) release from A549 cells was examined. The cloned mutated genes were used to complement a PAK fliC mutant in order to test for effects on motility and on IL-8 release by purified flagellar preparations. All the mutations, single or double, in the predicted TLR5 binding region reduced IL-8 signaling to less than 95% of the wild-type flagellin levels, but the single mutation outside the binding region had no effect. Changes made at two amino acid sites resulted in loss/reduction of motility; however, changes made at single sites, i.e., Q83A, L88A, R90A, M91A, L94A, and Q97A, had no effect on motility. The mutated genes encoding two of the motile but poorly signaling flagellins had no compensatory mutations to allow motility. Thus, while it is speculated that pathogen-associated molecular patterns (PAMPs) have evolved in locations that are essential to maintain function, it appears that there is tolerance for at least single amino acid changes in the PAMP of P. aeruginosa flagellin. The purpose of flagellin glycosylation in P. aeruginosa is unknown. In order to examine its role, if any, in signaling an inflammatory response, we used whole flagella from the motile chromosomal mutant strains PAKrfbC and PAO1rfbC, which are defective in flagellin glycosylation. IL-8 release from A549 cells stimulated with nonglycosylated flagellar preparations (having less then 1 picogram of LPS/μg) was significantly reduced compared to their respective wild-type flagellar preparations, indicating a role of flagellar glycosylation in the proinflammatory action of Pseudomonas flagellin. The basis of the latter activity is unknown, since the glycosylation sites are found in the D3 domain of flagellins and the TLR5 binding site is located in the D1 domain. Thus, P. aeruginosa flagellin has evolved additional flagellar signaling mechanisms over that described for Salmonella flagellin.
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Wan, Kirsty Y., Kyriacos C. Leptos i Raymond E. Goldstein. "Lag, lock, sync, slip: the many ‘phases’ of coupled flagella". Journal of The Royal Society Interface 11, nr 94 (6.05.2014): 20131160. http://dx.doi.org/10.1098/rsif.2013.1160.
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In a multitude of life's processes, cilia and flagella are found indispensable. Recently, the biflagellated chlorophyte alga Chlamydomonas has become a model organism for the study of ciliary motility and synchronization. Here, we use high-speed, high-resolution imaging of single pipette-held cells to quantify the rich dynamics exhibited by their flagella. Underlying this variability in behaviour are biological dissimilarities between the two flagella—termed cis and trans , with respect to a unique eyespot. With emphasis on the wild-type, we derive limit cycles and phase parametrizations for self-sustained flagellar oscillations from digitally tracked flagellar waveforms. Characterizing interflagellar phase synchrony via a simple model of coupled oscillators with noise, we find that during the canonical swimming breaststroke the cis flagellum is consistently phase-lagged relative to, while remaining robustly phase-locked with, the trans flagellum. Transient loss of synchrony, or phase slippage , may be triggered stochastically, in which the trans flagellum transitions to a second mode of beating with attenuated beat envelope and increased frequency. Further, exploiting this alga's ability for flagellar regeneration, we mechanically induced removal of one or the other flagellum of the same cell to reveal a striking disparity between the beatings of the cis and trans flagella, in isolation. These results are evaluated in the context of the dynamic coordination of Chlamydomonas flagella.
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Yang, Tsuey-Ching, Yu-Wei Leu, Hui-Chen Chang-Chien i Rouh-Mei Hu. "Flagellar Biogenesis of Xanthomonas campestris Requires the Alternative Sigma Factors RpoN2 and FliA and Is Temporally Regulated by FlhA, FlhB, and FlgM". Journal of Bacteriology 191, nr 7 (9.01.2009): 2266–75. http://dx.doi.org/10.1128/jb.01152-08.
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ABSTRACT In prokaryotes, flagellar biogenesis is a complicated process involving over 40 genes. The phytopathogen Xanthomonas campestris pv. campestris possesses a single polar flagellum, which is essential for the swimming motility. A σ54 activator, FleQ, has been shown to be required for the transcriptional activation of the flagellar type III secretion system (F-T3SS), rod, and hook proteins. One of the two rpoN genes, rpoN2, encoding σ54, is essential for flagellation. RpoN2 and FleQ direct the expression of a second alternative sigma FliA (σ28) that is essential for the expression of the flagellin FliC. FlgM interacts with FliA and represses the FliA regulons. An flgM mutant overexpressing FliC generates a deformed flagellum and displays an abnormal motility. Mutation in the two structural genes of F-T3SS, flhA and flhB, suppresses the production of FliC. Furthermore, FliA protein levels are decreased in an flhB mutant. A mutant defective in flhA, but not flhB, exhibits a decreased infection rate. In conclusion, the flagellar biogenesis of Xanthomonas campestris requires alternative sigma factors RpoN2 and FliA and is temporally regulated by FlhA, FlhB, and FlgM.
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Sun, Stella Y., Jason T. Kaelber, Muyuan Chen, Xiaoduo Dong, Yasaman Nematbakhsh, Jian Shi, Matthew Dougherty i in. "Flagellum couples cell shape to motility inTrypanosoma brucei". Proceedings of the National Academy of Sciences 115, nr 26 (11.06.2018): E5916—E5925. http://dx.doi.org/10.1073/pnas.1722618115.
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In the unicellular parasiteTrypanosoma brucei,the causative agent of human African sleeping sickness, complex swimming behavior is driven by a flagellum laterally attached to the long and slender cell body. Using microfluidic assays, we demonstrated thatT. bruceican penetrate through an orifice smaller than its maximum diameter. Efficient motility and penetration depend on active flagellar beating. To understand how active beating of the flagellum affects the cell body, we genetically engineeredT. bruceito produce anucleate cytoplasts (zoids and minis) with different flagellar attachment configurations and different swimming behaviors. We used cryo-electron tomography (cryo-ET) to visualize zoids and minis vitrified in different motility states. We showed that flagellar wave patterns reflective of their motility states are coupled to cytoskeleton deformation. Based on these observations, we propose a mechanism for how flagellum beating can deform the cell body via a flexible connection between the flagellar axoneme and the cell body. This mechanism may be critical forT. bruceito disseminate in its host through size-limiting barriers.
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Szabó, Zalán, Musa Sani, Maarten Groeneveld, Benham Zolghadr, James Schelert, Sonja-Verena Albers, Paul Blum, Egbert J. Boekema i Arnold J. M. Driessen. "Flagellar Motility and Structure in the Hyperthermoacidophilic Archaeon Sulfolobus solfataricus". Journal of Bacteriology 189, nr 11 (6.04.2007): 4305–9. http://dx.doi.org/10.1128/jb.00042-07.
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ABSTRACT Flagellation in archaea is widespread and is involved in swimming motility. Here, we demonstrate that the structural flagellin gene from the crenarchaeaon Sulfolobus solfataricus is highly expressed in stationary-phase-grown cells and under unfavorable nutritional conditions. A mutant in a flagellar auxiliary gene, flaJ, was found to be nonmotile. Electron microscopic imaging of the flagellum indicates that the filaments are composed of right-handed helices.
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Chen, Rui, Sarah B. Guttenplan, Kris M. Blair i Daniel B. Kearns. "Role of the σD-Dependent Autolysins in Bacillus subtilis Population Heterogeneity". Journal of Bacteriology 191, nr 18 (19.06.2008): 5775–84. http://dx.doi.org/10.1128/jb.00521-09.
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ABSTRACT Exponentially growing populations of Bacillus subtilis contain two morphologically and functionally distinct cell types: motile individuals and nonmotile multicellular chains. Motility differentiation arises because RNA polymerase and the alternative sigma factor σD activate expression of flagellin in a subpopulation of cells. Here we demonstrate that the peptidoglycan-remodeling autolysins under σD control, LytC, LytD, and LytF, are expressed in the same subpopulation of cells that complete flagellar synthesis. Morphological heterogeneity is explained by the expression of LytF that is necessary and sufficient for cell separation. Moreover, LytC is required for motility but not at the level of cell separation or flagellum biosynthesis. Rather, LytC appears to be important for flagellar function, and motility was restored to a LytC mutant by mutation of either lonA, encoding the LonA protease, or a gene encoding a previously unannotated swarming motility inhibitor, SmiA. We conclude that heterogeneous activation of σD-dependent gene expression is sufficient to explain both the morphological heterogeneity and functional heterogeneity present in vegetative B. subtilis populations.