Articles de revues : « Pili de type IVa »

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Evans, Katy J., Carey Lambert et R. Elizabeth Sockett. « Predation by Bdellovibrio bacteriovorus HD100 Requires Type IV Pili ». Journal of Bacteriology 189, n^o 13 (6 avril 2007) : 4850–59. http://dx.doi.org/10.1128/jb.01942-06.

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ABSTRACT Early electron microscopy and more recent studies in our laboratory of Bdellovibrio bacteriovorus cells indicated the presence of narrow fibers at the nonflagellar pole of this unusual predatory bacterium. Analysis of the B. bacteriovorus HD100 genome showed a complete set of genes potentially encoding type IV pili and an incomplete gene set for Flp pili; therefore, the role of type IV pili in the predatory life cycle of B. bacteriovorus HD100 was investigated. Alignment of the predicted PilA protein with known type IV pilins showed the characteristic conserved N terminus common to type IVa pilins. The pilA gene, encoding the type IV pilus fiber protein, was insertionally inactivated in multiple Bdellovibrio replicate cultures, and the effect upon the expression of other pilus genes was monitored by reverse transcriptase PCR. Interruption of pilA in replicate isolates abolished Bdellovibrio predatory capability in liquid prey cultures and on immobilized yellow fluorescent protein-labeled prey, but the mutants could be cultured prey independently. Expression patterns of pil genes involved in the formation of type IV pili were profiled across the predatory life cycle from attack phase predatory Bdellovibrio throughout the intraperiplasmic bdelloplast stages to prey lysis and in prey-independent growth. Taken together, the data show that type IV pili play a critical role in Bdellovibrio predation.

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Harvey, Hanjeong, Marc Habash, Francisca Aidoo et Lori L. Burrows. « Single-Residue Changes in the C-Terminal Disulfide-Bonded Loop of the Pseudomonas aeruginosa Type IV Pilin Influence Pilus Assembly and Twitching Motility ». Journal of Bacteriology 191, n^o 21 (28 août 2009) : 6513–24. http://dx.doi.org/10.1128/jb.00943-09.

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ABSTRACT PilA, the major pilin subunit of Pseudomonas aeruginosa type IV pili (T4P), is a principal structural component. PilA has a conserved C-terminal disulfide-bonded loop (DSL) that has been implicated as the pilus adhesinotope. Structural studies have suggested that DSL is involved in intersubunit interactions within the pilus fiber. PilA mutants with single-residue substitutions, insertions, or deletions in the DSL were tested for pilin stability, pilus assembly, and T4P function. Mutation of either Cys residue of the DSL resulted in pilins that were unable to assemble into fibers. Ala replacements of the intervening residues had a range of effects on assembly or function, as measured by changes in surface pilus expression and twitching motility. Modification of the C-terminal P-X-X-C type II beta-turn motif, which is one of the few highly conserved features in pilins across various species, caused profound defects in assembly and twitching motility. Expression of pilins with suspected assembly defects in a pilA pilT double mutant unable to retract T4P allowed us to verify which subunits were physically unable to assemble. Use of two different PilA antibodies showed that the DSL may be an immunodominant epitope in intact pili compared with pilin monomers. Sequence diversity of the type IVa pilins likely reflects an evolutionary compromise between retention of function and antigenic variation. The consequences of DSL sequence changes should be evaluated in the intact protein since it is technically feasible to generate DSL-mimetic peptides with mutations that will not appear in the natural repertoire due to their deleterious effects on assembly.

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de Bentzmann, Sophie, Marianne Aurouze, Geneviève Ball et Alain Filloux. « FppA, a Novel Pseudomonas aeruginosa Prepilin Peptidase Involved in Assembly of Type IVb Pili ». Journal of Bacteriology 188, n^o 13 (1 juillet 2006) : 4851–60. http://dx.doi.org/10.1128/jb.00345-06.

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ABSTRACT Several subclasses of type IV pili have been described according to the characteristics of the structural prepilin subunit. Whereas molecular mechanisms of type IVa pilus assembly have been well documented for Pseudomonas aeruginosa and involve the PilD prepilin peptidase, no type IVb pili have been described in this microorganism. One subclass of type IVb prepilins has been identified as the Flp prepilin subfamily. Long and bundled Flp pili involved in tight adherence have been identified in Actinobacillus actinomycetemcomitans, for which assembly was due to a dedicated machinery encoded by the tad-rcp locus. A similar flp-tad-rcp locus containing flp, tad, and rcp gene homologues was identified in the P. aeruginosa genome. The function of these genes has been investigated, which revealed their involvement in the formation of extracellular Flp appendages. We also identified a gene (designated by open reading frame PA4295) outside the flp-tad-rcp locus, that we named fppA, encoding a novel prepilin peptidase. This is the second enzyme of this kind found in P. aeruginosa; however, it appears to be truncated and is similar to the C-terminal domain of the previously characterized PilD peptidase. In this study, we show that FppA is responsible for the maturation of the Flp prepilin and belongs to the aspartic acid protease family. We also demonstrate that FppA is required for the assembly of cell surface appendages that we called Flp pili. Finally, we observed an Flp-dependent bacterial aggregation process on the epithelial cell surface and an increased biofilm phenotype linked to Flp pilus assembly.

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Wairuri, Charles K., Jacquie E. van der Waals, Antoinette van Schalkwyk et Jacques Theron. « Ralstonia solanacearum Needs Flp Pili for Virulence on Potato ». Molecular Plant-Microbe Interactions® 25, n^o 4 (avril 2012) : 546–56. http://dx.doi.org/10.1094/mpmi-06-11-0166.

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Type IV pili are virulence factors in various bacteria. Several subclasses of type IV pili have been described according to the characteristics of the structural prepilin subunit. Although type IVa pili have been implicated in the virulence of Ralstonia solanacearum, type IVb pili have not previously been described in this plant pathogen. Here, we report the characterization of two distinct tad loci in the R. solanacearum genome. The tad genes encode functions necessary for biogenesis of the Flp subfamily of type IVb pili initially described for the periodontal pathogen Aggregatibacter actinomycetemcomitans. To determine the role of the tad loci in R. solanacearum virulence, we mutated the tadA2 gene located in the megaplasmid that encodes a predicted NTPase previously reported to function as the energizer for Flp pilus biogenesis. Characterization of the tadA2 mutant revealed that it was not growth impaired in vitro or in planta, produced wild-type levels of exopolysaccharide galactosamine, and exhibited swimming and twitching motility comparable with the wild-type strain. However, the tadA2 mutant was impaired in its ability to cause wilting of potato plants. This is the first report where type IVb pili in a phytopathogenic bacterium contribute significantly to plant pathogenesis.

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Chlebek, Jennifer L., Hannah Q. Hughes, Aleksandra S. Ratkiewicz, Rasman Rayyan, Joseph Che-Yen Wang, Brittany E. Herrin, Triana N. Dalia, Nicolas Biais et Ankur B. Dalia. « PilT and PilU are homohexameric ATPases that coordinate to retract type IVa pili ». PLOS Genetics 15, n^o 10 (18 octobre 2019) : e1008448. http://dx.doi.org/10.1371/journal.pgen.1008448.

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Hughes, Hannah Q., Nicholas D. Christman, Triana N. Dalia, Courtney K. Ellison et Ankur B. Dalia. « The PilT retraction ATPase promotes both extension and retraction of the MSHA type IVa pilus in Vibrio cholerae ». PLOS Genetics 18, n^o 12 (21 décembre 2022) : e1010561. http://dx.doi.org/10.1371/journal.pgen.1010561.

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Diverse bacterial species use type IVa pili (T4aP) to interact with their environments. The dynamic extension and retraction of T4aP is critical for their function, but the mechanisms that regulate this dynamic activity remain poorly understood. T4aP are typically extended via the activity of a dedicated extension motor ATPase and retracted via the action of an antagonistic retraction motor ATPase called PilT. These motors are generally functionally independent, and loss of PilT commonly results in T4aP hyperpiliation due to undeterred pilus extension. However, for the mannose-sensitive hemagglutinin (MSHA) T4aP of Vibrio cholerae, the loss of PilT unexpectedly results in a loss of surface piliation. Here, we employ a combination of genetic and cell biological approaches to dissect the underlying mechanism. Our results demonstrate that PilT is necessary for MSHA pilus extension in addition to its well-established role in promoting MSHA pilus retraction. Through a suppressor screen, we also provide genetic evidence that the MshA major pilin impacts pilus extension. Together, these findings contribute to our understanding of the factors that regulate pilus extension and describe a previously uncharacterized function for the PilT motor ATPase.

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Iruegas, Ruben, Katharina Pfefferle, Stephan Göttig, Beate Averhoff et Ingo Ebersberger. « Feature architecture aware phylogenetic profiling indicates a functional diversification of type IVa pili in the nosocomial pathogen Acinetobacter baumannii ». PLOS Genetics 19, n^o 7 (27 juillet 2023) : e1010646. http://dx.doi.org/10.1371/journal.pgen.1010646.

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The Gram-negative bacterial pathogen Acinetobacter baumannii is a major cause of hospital-acquired opportunistic infections. The increasing spread of pan-drug resistant strains makes A. baumannii top-ranking among the ESKAPE pathogens for which novel routes of treatment are urgently needed. Comparative genomics approaches have successfully identified genetic changes coinciding with the emergence of pathogenicity in Acinetobacter. Genes that are prevalent both in pathogenic and a-pathogenic Acinetobacter species were not considered ignoring that virulence factors may emerge by the modification of evolutionarily old and widespread proteins. Here, we increased the resolution of comparative genomics analyses to also include lineage-specific changes in protein feature architectures. Using type IVa pili (T4aP) as an example, we show that three pilus components, among them the pilus tip adhesin ComC, vary in their Pfam domain annotation within the genus Acinetobacter. In most pathogenic Acinetobacter isolates, ComC displays a von Willebrand Factor type A domain harboring a finger-like protrusion, and we provide experimental evidence that this finger conveys virulence-related functions in A. baumannii. All three genes are part of an evolutionary cassette, which has been replaced at least twice during A. baumannii diversification. The resulting strain-specific differences in T4aP layout suggests differences in the way how individual strains interact with their host. Our study underpins the hypothesis that A. baumannii uses T4aP for host infection as it was shown previously for other pathogens. It also indicates that many more functional complexes may exist whose precise functions have been adjusted by modifying individual components on the domain level.

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Orndorff, Paul E., Aditya Devapali, Sarah Palestrant, Aaron Wyse, Mary Lou Everett, R. Randal Bollinger et William Parker. « Immunoglobulin-Mediated Agglutination of and Biofilm Formation by Escherichia coli K-12 Require the Type 1 Pilus Fiber ». Infection and Immunity 72, n^o 4 (avril 2004) : 1929–38. http://dx.doi.org/10.1128/iai.72.4.1929-1938.2004.

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ABSTRACT The binding of human secretory immunoglobulin A (SIgA), the primary immunoglobulin in the gut, to Escherichia coli is thought to be dependent on type 1 pili. Type 1 pili are filamentous bacterial surface attachment organelles comprised principally of a single protein, the product of the fimA gene. A minor component of the pilus fiber (the product of the fimH gene, termed the adhesin) mediates attachment to a variety of host cell molecules in a mannose inhibitable interaction that has been extensively described. We found that the aggregation of E. coli K-12 by human secretory IgA (SIgA) was dependent on the presence of the pilus fiber, even in the absence of the mannose specific adhesin or in the presence of 25 mM α-CH3Man. The presence of pilus without adhesin also facilitated SIgA-mediated biofilm formation on polystyrene, although biofilm formation was stronger in the presence of the adhesin. IgM also mediated aggregation and biofilm formation in a manner dependent on pili with or without adhesin. These findings indicate that the pilus fiber, even in the absence of the adhesin, may play a role in biologically important processes. Under conditions in which E. coli was agglutinated by SIgA, the binding of SIgA to E. coli was not increased by the presence of the pili, with or without adhesin. This observation suggests that the pili, with or without adhesin, affect factors such as cell surface rigidity or electrostatic repulsion, which can affect agglutination but which do not necessarily determine the level of bound immunoglobulin.

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Dahlgren, U. I., S. Ahlstedt et L. A. Hanson. « The localization of the antibody response in milk or bile depends on the nature of the antigen. » Journal of Immunology 138, n^o 5 (1 mars 1987) : 1397–402. http://dx.doi.org/10.4049/jimmunol.138.5.1397.

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Abstract Immunization in the Peyer's patches of rats with horse spleen ferritin or Escherichia coli 06 carrying type 1 pili resulted in an IgA antibody response detected in milk and bile and an IgG and IgM antibody response in serum, milk, and bile. The IgA antibody response to type 1 pili was as a mean 5.0-fold higher in milk than in bile. In contrast IgA antibody activity to 06 LPS was as a mean 6.3-fold higher in bile than in milk. The IgA antibodies to ferritin were randomly distributed between milk and bile. The IgG and IgM antibody activity to all three antigens studied were higher in the milk than in the bile. The secretory antibody response could be transferred from immunized rats to unimmunized rats with mesenteric lymph node cells (MLN) taken from donor rats 4 days after immunization in the Peyer's patches. IgA antibodies to pili and ferritin appeared solely in the milk of the recipients, whereas IgA antibodies to the 06 LPS only appeared in the bile. The ratios serum:milk and serum:bile for the IgG and IgM antibodies indicated an antigen-specific direction of homing with local production of these two isotypes primarily in the mammary gland. Antibody-forming cells of the IgA class could not be detected in the MLN on the day the cells were transferred. It is concluded that the difference seen in antibody distribution between milk and bile is not due to dissemination of antigen, but instead a result of different homing or expansion at the mucosal-glandular site dependent on the antigen specificity of the migrating cells.

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Quigley, Bernard R., Matthew Hatkoff, David G. Thanassi, Mahamoudou Ouattara, Zehava Eichenbaum et June R. Scott. « A Foreign Protein Incorporated on the Tip of T3 Pili in Lactococcus lactis Elicits Systemic and Mucosal Immunity ». Infection and Immunity 78, n^o 3 (22 décembre 2009) : 1294–303. http://dx.doi.org/10.1128/iai.01037-09.

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ABSTRACT The use of Lactococcus lactis to deliver a chosen antigen to the mucosal surface has been shown to elicit an immune response in mice and is a possible method of vaccination in humans. The recent discovery on Gram-positive bacteria of pili that are covalently attached to the bacterial surface and the elucidation of the residues linking the major and minor subunits of such pili suggests that the presentation of an antigen on the tip of pili external to the surface of L. lactis might constitute a successful vaccine strategy. As a proof of principle, we have fused a foreign protein (the Escherichia coli maltose-binding protein) to the C-terminal region of the native tip protein (Cpa) of the T3 pilus derived from Streptococcus pyogenes and expressed this fusion protein (MBP*) in L. lactis. We find that MBP* is incorporated into pili in this foreign host, as shown by Western blot analyses of cell wall proteins and by immunogold electron microscopy. Furthermore, since the MBP* on these pili retains its native biological activity, it appears to retain its native structure. Mucosal immunization of mice with this L. lactis strain expressing pilus-linked MBP* results in production of both a systemic and a mucosal response (IgG and IgA antibodies) against the MBP antigen. We suggest that this type of mucosal vaccine delivery system, which we term UPTOP (for unhindered presentation on tips of pili), may provide an inexpensive and stable alternative to current mechanisms of immunization for many serious human pathogens.

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Reardon, Patrick N., et Karl T. Mueller. « Structure of the Type IVa Major Pilin from the Electrically Conductive Bacterial Nanowires ofGeobacter sulfurreducens ». Journal of Biological Chemistry 288, n^o 41 (21 août 2013) : 29260–66. http://dx.doi.org/10.1074/jbc.m113.498527.

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Boddey, Justin A., Cameron P. Flegg, Chris J. Day, Ifor R. Beacham et Ian R. Peak. « Temperature-Regulated Microcolony Formation by Burkholderia pseudomallei Requires pilA and Enhances Association with Cultured Human Cells ». Infection and Immunity 74, n^o 9 (septembre 2006) : 5374–81. http://dx.doi.org/10.1128/iai.00569-06.

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ABSTRACT Burkholderia pseudomallei is the causative agent of melioidosis, a potentially fatal disease that is endemic to Northern Australia and Southeast Asia and is acquired from soil or water. Adherence of B. pseudomallei 08 to cultured cells increases dramatically following prior growth at 30°C or less compared to that following prior growth at 37°C. Here, we show that this occurs almost entirely as the result of microcolony formation (bacterium-bacterium interactions) following growth at 27°C but not at 37°C, which considerably enhances bacterial association with eukaryotic cells. Further, we demonstrate that the type IVA pilin-encoding gene, pilA, is essential for microcolony development by B. pseudomallei 08, and thus optimum association with eukaryotic cells, but is not required for direct adherence (bacterium-cell interactions). In contrast, although the B. pseudomallei genome sequence strain, K96243, also contains transcriptionally active pilA, microcolony formation rarely occurs following growth at either 27°C or 37°C and cell association occurs significantly less than with strain 08. Analysis of pilA transcription in 08 identified that pilA is dramatically upregulated under microcolony-forming conditions, viz., growth at low temperature, and association with eukaryotic cells; the pattern of transcription of pilA in K96243 differed from that in 08. Our study also suggests that biofilm formation by B. pseudomallei 08 and K96243 on polyvinylchloride is not mediated by pilA. Adherence and microcolony formation, and pilA transcription, vary between strains, consistent with known genomic variation in B. pseudomallei, and these phenotypes may be relevant to colonization from the environment.

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Allison, Tara M., Sean Conrad et Peter Castric. « The group I pilin glycan affects type IVa pilus hydrophobicity and twitching motility in Pseudomonas aeruginosa 1244 ». Microbiology 161, n^o 9 (1 septembre 2015) : 1780–89. http://dx.doi.org/10.1099/mic.0.000128.

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Bollinger, R. Randal, Mary Lou Everett, Shaina D. Wahl, Yu-Huei Lee, Paul E. Orndorff et William Parker. « Secretory IgA and mucin-mediated biofilm formation by environmental strains of Escherichia coli : role of type 1 pili ». Molecular Immunology 43, n^o 4 (février 2006) : 378–87. http://dx.doi.org/10.1016/j.molimm.2005.02.013.

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Colicchio, Roberta, Chiara Pagliuca, Gabiria Pastore, Annunziata Gaetana Cicatiello, Caterina Pagliarulo, Adelfia Talà, Elena Scaglione et al. « Fitness Cost of Rifampin Resistance in Neisseria meningitidis:In VitroStudy of Mechanisms Associated withrpoBH553Y Mutation ». Antimicrobial Agents and Chemotherapy 59, n^o 12 (28 septembre 2015) : 7637–49. http://dx.doi.org/10.1128/aac.01746-15.

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ABSTRACTRifampin chemoprophylaxis againstNeisseria meningitidisinfections led to the onset of rifampin resistance in clinical isolates harboring point mutations in therpoBgene, coding for the RNA polymerase β chain. These resistant strains are rare in medical practice, suggesting their decreased fitness in the human host. In this study, we isolated rifampin-resistantrpoBmutants from hypervirulent serogroup C strain 93/4286 and analyzed their different properties, including the ability to grow/survive in different culture media and in differentiated THP-1 human monocytes and to compete with the wild-type strainin vitro. Our results demonstrate that differentrpoBmutations (H553Y, H553R, and S549F) may have different effects, ranging from low- to high-cost effects, on bacterial fitnessin vitro. Moreover, we found that the S549F mutation confers temperature sensitivity, possibly explaining why it is observed very rarely in clinical isolates. Comparative high-throughput RNA sequencing analysis of bacteria grown in chemically defined medium demonstrated that the low-cost H553Y substitution resulted in global transcriptional changes that functionally mimic the stringent response. Interestingly, many virulence-associated genes, including those coding for meningococcal type IV pili, porin A, adhesins/invasins, IgA protease, two-partner secretion system HrpA/HrpB, enzymes involved in resistance to oxidative injury, lipooligosaccharide sialylation, and capsular polysaccharide biosynthesis, were downregulated in the H553Y mutant compared to their level of expression in the wild-type strain. These data might account for the reduced capacity of this mutant to grow/survive in differentiated THP-1 cells and explain the rarity of H553Y mutants among clinical isolates.

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Reardon-Robinson, Melissa E., Chenggang Wu, Arunima Mishra, Chungyu Chang, Naomi Bier, Asis Das et Hung Ton-That. « Pilus hijacking by a bacterial coaggregation factor critical for oral biofilm development ». Proceedings of the National Academy of Sciences 111, n^o 10 (24 février 2014) : 3835–40. http://dx.doi.org/10.1073/pnas.1321417111.

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The formation of dental plaque, a highly complex biofilm that causes gingivitis and periodontitis, requires specific adherence among many oral microbes, including the coaggregation ofActinomyces oriswithStreptococcus oralisthat helps to seed biofilm development. Here, we report the discovery of a key coaggregation factor for this process. This protein, which we named coaggregation factor A (CafA), is one of 14 cell surface proteins with the LPXTG motif predicted inA. orisMG1, whose function was hitherto unknown. By systematic mutagenesis of each of these genes and phenotypic characterization, we found that theActinomyces/Streptococcuscoaggregation is only abolished by deletion ofcafA. Subsequent biochemical and cytological experiments revealed that CafA constitutes the tip of a unique form of the type 2 fimbria long known for its role in coaggregation. The direct and predominant role of CafA in adherence is evident from the fact that CafA or an antibody against CafA inhibits coaggregation, whereas the shaft protein FimA or a polyclonal antibody against FimA has no effect. Remarkably, FimA polymerization was blocked by deletion of genes for both CafA and FimB, the previously described tip protein of the type 2 fimbria. Together, these results indicate that some surface proteins not linked to a pilus gene cluster in Gram-positive bacteria may hijack the pilus. These unique tip proteins displayed on a common pilus shaft may serve distinct physiological functions. Furthermore, the pilus shaft assembly in Gram-positive bacteria may require a tip, as is true for certain Gram-negative bacterial pili.

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Khoobbakht, Dorna, Shohreh Zare Karizi, Mohammad Javad Motamedi, Rouhollah Kazemi, Pooneh Roghanian et Jafar Amani. « Immunogenicity Evaluation of Chimeric Subunit Vaccine Comprising Adhesion Coli Surface Antigens from Enterotoxigenic Escherichia coli ». Journal of Molecular Microbiology and Biotechnology 29, n^o 1-6 (2019) : 91–100. http://dx.doi.org/10.1159/000509708.

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Enterotoxigenic Escherichia coli (ETEC) is the most common agent of diarrhea morbidity in developing countries. ETEC adheres to host intestinal epithelial cells via various colonization factors. The CooD and CotD proteins play a significant role in bacteria binding to the intestinal epithelial cells as adhesin tip subunits of CS1 and CS2 pili. The purpose here was to design a new construction containing cooD and cotD genes and use several types of bioinformatics software to predict the structural and immunological properties of the designed antigen. The fusion gene was synthesized with codon bias of E. coli in order to increase the expression level of the protein. The amino acid sequences, protein structure, and immunogenicity properties of potential antigens were analyzed in silico. The chimeric protein was expressed in E. coliBL21 (DE3). The antigenicity of the recombinant proteins was verified by Western blotting and ELISA. In order to assess the induced immunity, the immunized mice were challenged with wild-type ETEC by an intraperitoneal route. Immunological analyses showed the production of a high titer of IgG serum with no sign of serum-mucosal IgA antibody response. The result of the challenge assay showed that 30% of immunized mice survived. The results of this study showed that CooD-CotD recombinant protein can stimulate immunity against ETEC. The designed chimera could be a prototype for the subunit vaccine, which is worthy of further consideration.

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Marinova, S., P. Nenkov, R. Markova, S. Nikolaeva, R. Kostadinova, I. Mitov et M. Vretenarska. « Cellular and Humoral Systemic and Mucosal Immune Responses Stimulated by an Oral Polybacterial Immunomodulator in Patients with Chronic Urinary Tract Infections ». International Journal of Immunopathology and Pharmacology 18, n^o 3 (juillet 2005) : 457–73. http://dx.doi.org/10.1177/039463200501800306.

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An oral polybacterial immunomodulator Urostim (U), composed of killed cells and their lysates from E. coli expressing type 1 and P-pili, E. coli Re mutant, P. mirabilis, K. pneumoniae and E. faecalis was created for immunoprophylaxis and immunotherapy of urinary tract infections (UTIs). In experimental animal models, the stimulating effect of U on lymphocyte functional activity, macrophage phagocytosis and antibody producing cells, was established. In this study the immuno-modulating effects of U on the proliferating capacity and ultrastructural morphologic changes of lymphocytes, cytokine production and specific systemic humoral and mucosal immune responses in patients with UTIs have been evaluated. Patients enrolled in the study, received orally 50 mg U daily for a period of three months. On days 0,30 and 90 a quantitative analysis was performed on lymphoproliferative responses to polyclonal mitogens, IL-2 and the specific antigen U, the production of specific serum and saliva IgA, IgM and IgG antibodies to all components of U and the concentration of pro-inflammatory cytokines. There was significant improvement of non-specific and specific lymphoproliferative responses on days 30 and 90 after the onset of treatment with U, confirmed by electron-microscopic studies. The highest concentrations of serum proinflammatory cytokines TNF-α, IL-1β, and IL-6 were registered at baseline followed by a decrease until the end of the observation period. This finding correlates with the gradual decrease of immune activation as measured by the spontaneous lymphocyte proliferation. Data from the production of specific antibacterial antibodies in serum and saliva show two types of reactions. The first type was registered in patients with low pre-treatment levels in whom the concentration of specific antibodies increased on days 30 and 90. The second type of reaction was observed in patients with high pre-treatment levels, which dropped on day 30 and were usually followed by an increase at the end of the study. These results provide evidence for the immuno-modulating effect of U. Our data show that the oral administration of the polybacterial immunomodulator Urostim stimulates adequate cellular and humoral systemic and mucosal immune responses in patients with chronic UTIs.

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Biais, Nicolas. « Pili de type IV ». médecine/sciences 25, n^o 5 (mai 2009) : 437–38. http://dx.doi.org/10.1051/medsci/2009255437.

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De La Fuente, Leonardo, Emilie Montanes, Yizhi Meng, Yaxin Li, Thomas J. Burr, H. C. Hoch et Mingming Wu. « Assessing Adhesion Forces of Type I and Type IV Pili of Xylella fastidiosa Bacteria by Use of a Microfluidic Flow Chamber ». Applied and Environmental Microbiology 73, n^o 8 (9 février 2007) : 2690–96. http://dx.doi.org/10.1128/aem.02649-06.

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ABSTRACT Xylella fastidiosa, a bacterium responsible for Pierce's disease in grapevines, possesses both type I and type IV pili at the same cell pole. Type IV pili facilitate twitching motility, and type I pili are involved in biofilm development. The adhesiveness of the bacteria and the roles of the two pili types in attachment to a glass substratum were evaluated using a microfluidic flow chamber in conjunction with pilus-defective mutants. The average adhesion force necessary to detach wild-type X. fastidiosa cells was 147 ± 11 pN. Mutant cells possessing only type I pili required a force of 204 ± 22 pN for removal, whereas cells possessing only type IV pili required 119 ± 8 pN to dislodge these cells. The experimental results demonstrate that microfluidic flow chambers are useful and convenient tools for assessing the drag forces necessary for detaching bacterial cells and that with specific pilus mutants, the role of the pilus type can be further assessed.

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Shoji, Mikio, Satoshi Shibata, Takayuki Sueyoshi, Mariko Naito et Koji Nakayama. « Biogenesis of Type V pili ». Microbiology and Immunology 64, n^o 10 (9 septembre 2020) : 643–56. http://dx.doi.org/10.1111/1348-0421.12838.

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van Schaik, Erin J., Carmen L. Giltner, Gerald F. Audette, David W. Keizer, Daisy L. Bautista, Carolyn M. Slupsky, Brian D. Sykes et Randall T. Irvin. « DNA Binding : a Novel Function of Pseudomonas aeruginosa Type IV Pili ». Journal of Bacteriology 187, n^o 4 (15 février 2005) : 1455–64. http://dx.doi.org/10.1128/jb.187.4.1455-1464.2005.

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ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa produces multifunctional, polar, filamentous appendages termed type IV pili. Type IV pili are involved in colonization during infection, twitching motility, biofilm formation, bacteriophage infection, and natural transformation. Electrostatic surface analysis of modeled pilus fibers generated from P. aeruginosa strain PAK, K122-4, and KB-7 pilin monomers suggested that a solvent-exposed band of positive charge may be a common feature of all type IV pili. Several functions of type IV pili, including natural transformation and biofilm formation, involve DNA. We investigated the ability of P. aeruginosa type IV pili to bind DNA. Purified PAK, K122-4, and KB-7 pili were observed to bind both bacterial plasmid and salmon sperm DNA in a concentration-dependent and saturable manner. PAK pili had the highest affinity for DNA, followed by K122-4 and KB-7 pili. DNA binding involved backbone interactions and preferential binding to pyrimidine residues even though there was no evidence of sequence-specific binding. Pilus-mediated DNA binding was a function of the intact pilus and thus required elements present in the quaternary structure. However, binding also involved the pilus tip as tip-specific, but not base-specific, antibodies inhibited DNA binding. The conservation of a Thr residue in all type IV pilin monomers examined to date, along with the electrostatic data, implies that DNA binding is a conserved function of type IV pili. Pilus-mediated DNA binding could be important for biofilm formation both in vivo during an infection and ex vivo on abiotic surfaces.

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Persat, Alexandre, Yuki F. Inclan, Joanne N. Engel, Howard A. Stone et Zemer Gitai. « Type IV pili mechanochemically regulate virulence factors inPseudomonas aeruginosa ». Proceedings of the National Academy of Sciences 112, n^o 24 (3 juin 2015) : 7563–68. http://dx.doi.org/10.1073/pnas.1502025112.

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Bacteria have evolved a wide range of sensing systems to appropriately respond to environmental signals. Here we demonstrate that the opportunistic pathogenPseudomonas aeruginosadetects contact with surfaces on short timescales using the mechanical activity of its type IV pili, a major surface adhesin. This signal transduction mechanism requires attachment of type IV pili to a solid surface, followed by pilus retraction and signal transduction through the Chp chemosensory system, a chemotaxis-like sensory system that regulates cAMP production and transcription of hundreds of genes, including key virulence factors. Like other chemotaxis pathways, pili-mediated surface sensing results in a transient response amplified by a positive feedback that increases type IV pili activity, thereby promoting long-term surface attachment that can stimulate additional virulence and biofilm-inducing pathways. The methyl-accepting chemotaxis protein-like chemosensor PilJ directly interacts with the major pilin subunit PilA. Our results thus support a mechanochemical model where a chemosensory system measures the mechanically induced conformational changes in stretched type IV pili. These findings demonstrate thatP. aeruginosanot only uses type IV pili for surface-specific twitching motility, but also as a sensor regulating surface-induced gene expression and pathogenicity.

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Stone, Barbara J., et Yousef Abu Kwaik. « Natural Competence for DNA Transformation by Legionella pneumophila and Its Association with Expression of Type IV Pili ». Journal of Bacteriology 181, n^o 5 (1 mars 1999) : 1395–402. http://dx.doi.org/10.1128/jb.181.5.1395-1402.1999.

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ABSTRACT We have recently described the expression of two pili of different lengths on the surface of Legionella pneumophila (B. J. Stone and Y. Abu Kwaik, Infect. Immun. 66:1768–1775, 1998). Production of long pili requires a functional pilE L locus, encoding a type IV pilin protein. Since type IV pili in Neisseria gonorrhoeaeare associated with competence for DNA transformation, we examined the competence of L. pneumophila for DNA transformation under conditions that allowed the expression of type IV pili. We show that L. pneumophila is naturally competent for DNA transformation by isogenic chromosomal DNA and by plasmid DNA containing L. pneumophila DNA. Many different L. pneumophila loci are able to transform L. pneumophilaafter addition of plasmid DNA, including gspA,ppa, asd, and pilE L. The transformation frequency is reduced when competing DNA containing either L. pneumophila DNA or vector sequences is added to the bacteria, suggesting that uptake-specific sequences may not be involved in DNA uptake. Competence for DNA transformation correlates with expression of the type IV pili, and apilE L mutant defective in expression of type IV pili is not competent for DNA transformation. Complementation of the mutant for competence is restored by the reintroduction of a cosmid that restores production of type IV pili. Minimal competence is restored to the mutant by introduction of pilE Lalone. We conclude that competence for DNA transformation in L. pneumophila is associated with expression of the type IV pilus and results in recombination of L. pneumophila DNA into the chromosome. Since expression of type IV pili also facilitates attachment of L. pneumophila to mammalian cells and protozoa, we designated the type IV pili CAP (for competence- and adherence-associated pili).

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Mu, Xiang-Qi, Edward H. Egelman et Esther Bullitt. « Structure and Function of Hib Pili from Haemophilus influenzae Type b ». Journal of Bacteriology 184, n^o 17 (1 septembre 2002) : 4868–74. http://dx.doi.org/10.1128/jb.184.17.4868-4874.2002.

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ABSTRACT Pathogenic bacteria are specifically adapted to bind to their customary host. Disease is then caused by subsequent colonization and/or invasion of the local environmental niche. Initial binding of Haemophilus influenzae type b to the human nasopharynx is facilitated by Hib pili, filaments expressed on the bacterial surface. With three-dimensional reconstruction of electron micrograph images, we show that Hib pili comprise a helix 70 Å in diameter with threefold symmetry. The Hib pilus filament has 3.0 subunits per turn, with each set of three subunits translated 26.9 Å along and rotated 53 degrees about the helical axis. Amino acid sequence analysis of pilins from Hib pili and from P-pili expressed on uropathogenic Escherichia coli were used to predict the physical location of the highly variable and immunogenic region of the HifA pilin in the Hib pilus structure. Structural differences between Hib pili and P-pili suggest a difference in the strategies by which bacteria remain bound to their host cells: P-pili were shown to be capable of unwinding to five times their original length (E. Bullitt and L. Makowski, Nature 373:164-167, 1995), while damage to Hib pili occurs by slight shearing of subunits with respect to those further along the helical axis. This capacity to resist unwinding may be important for continued adherence of H. influenzae type b to the nasopharynx, where the three-stranded Hib pilus filaments provide a robust tether to withstand coughs and sneezes.

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Van Eyssen, Shelly Roselyn, Anastasia Samarkina, Ovgu Isbilen, Merve Suzan Zeden et Ender Volkan. « FimH and Type 1 Pili Mediated Tumor Cell Cytotoxicity by Uropathogenic Escherichia coli In Vitro ». Pathogens 12, n^o 6 (23 mai 2023) : 751. http://dx.doi.org/10.3390/pathogens12060751.

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Uropathogenic Escherichia coli express hairlike proteinaceous surface projections, known as chaperone–usher pathway (CUP) pili. Type 1 pili are CUP pili with well-established pathogenic properties. The FimH adhesin subunit of type 1 pili plays a key role in the pathogenesis of urinary tract infections (UTIs) as it mediates the adhesion of the bacteria to urothelial cells of the bladder. In this study, two breast cancer cell lines, MDA-MB-231 and MCF-7, were used to demonstrate the cytotoxic activities of type 1 piliated uropathogenic E. coli UTI89 on breast cancer cells in a type 1 pili and FimH-mediated manner. E. coli were grown in static and shaking conditions to induce or inhibit optimal type 1 pili biogenesis, respectively. Deletion constructs of UTI89 ΔfimH and a complemented strain (UTI89 ΔfimH/pfimH) were further utilized to genetically assess the effect of type 1 pili and FimH on cancer cell viability. After incubation with the different strains, cytotoxicity was measured using trypan blue exclusion assays. UTI89 grown statically caused significant cytotoxicity in both breast cancer cell lines whereas cytotoxicity was reduced when the cells were incubated with bacteria grown under shaking conditions. The incubation of both MDA-MB-231 and MCF-7 with UTI89 Δfim operon or ΔfimH showed a significant reduction in cytotoxicity exerted by the bacterial strains, revealing that type 1 pili expression was necessary for cytotoxicity. Complementing the ΔfimH strain with pfimH reversed the phenotype, leading to a significant increase in cytotoxicity. Incubating type 1 pili expressing bacteria with the competitive FimH inhibitor D-mannose before cancer cell treatment also led to a significant reduction in cytotoxicity on both MDA-MB-231 and MCF-7 cancer cells, compared to vehicle control or D-mannose alone, indicating the requirement for functional FimH for cytotoxicity. Overall, our results reveal that, as opposed to UTI89 lacking type 1 pili, type 1 piliated UTI89 causes significant cancer cell mortality in a FimH-mediated manner, that is decreased with D-mannose.

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Sherman, P., R. Soni et E. Boedeker. « Role of Type 1 Somatic Pili (Fimbriae) in Mucosal Attachment of the Enteroadherent Escherichia coli, Strain RDEC‐1, in Rabbits ». Journal of Pediatric Gastroenterology and Nutrition 7, n^o 4 (juillet 1988) : 594–601. http://dx.doi.org/10.1002/j.1536-4801.1988.tb09597.x.

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Summary:We have previously shown that attachment of the rabbit enteroadherent Escherichia coli, strain RDEC‐1, to ileal brush borders in vitro is mediated by both man‐nose‐resistant, AF/R1 pili and mannose‐sensitive, type 1 pili. Because the role of type 1, somatic pili as adhesins that mediate bacterial enteroadherence in vivo remains controversial, we examined adherence of RDEC‐1 expressing either type 1 pili or AF/R1 pili to rabbit ileum in ligated loops and after oral infection of rabbits. A rabbit fecal commensal E. coli, 640, which also expressed type 1 pili was used as a control. After oral infection of rabbits we evaluated: (a) diarrhea, (b) fecal shedding of organisms, (c) luminal colonization of jejunum and ileum, and (d) mucosal adherence of bacteria to jejunum, ileum, and colon. RDEC‐1 expressing either type 1 or AF/R1 pili adhered to enterocytes both in ileal ligated loops and in the distal ileum, cecum, and proximal colon of infected rabbits. In contrast, enteroadherence of 640 was not observed. Diarrhea developed in rabbits challenged with either type 1 or AF/R1 piliated RDEC‐1, but not in rabbits fed 640. Seven days after infection of rabbits with RDEC‐1 bearing type 1 pili, luminal colonization of jejunum (4.22 ± 0.55 CFU/g, X ± SE) and ileum (6.34 ± 0.55) was the same as after infection with AF/R1 piliated RDEC‐1 (jejunum 4.47 ± 0.20, ileum 5.81 ± 0.70) and significantly greater than luminal colonization by type 1 piliated 640 (jejunum > 2.22 ± 0.14, ileum > 2.06 ± 0.15). Indirect immunofluorescence using polyvalent antiserum produced against type 1 pili (purified from RDEC‐1) was positive for RDEC‐1 adherent to ileal enterocytes both in ligated loops and after oral infection of rabbits. These findings support the hypothesis that type 1 pili could mediate adherence of enteroadherent E. coli to intestinal mucosal surfaces during infection in vivo.

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Carty, Helen, et Donald G. Shaw. « Osteogenesis Imperfecta Type IVA ». Acta Paediatrica 77, n^o 5 (septembre 1988) : 752–53. http://dx.doi.org/10.1111/j.1651-2227.1988.tb10742.x.

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Paterson, C. R., S. J. McAllion et J. W. Shaw. « Osteogenesis lmperfecta Type IVA ». Acta Paediatrica 77, n^o 5 (septembre 1988) : 753–54. http://dx.doi.org/10.1111/j.1651-2227.1988.tb10743.x.

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Hasegawa, Y. « Phakomatosis pigmentovascularis type IVa ». Archives of Dermatology 121, n^o 5 (1 mai 1985) : 651–55. http://dx.doi.org/10.1001/archderm.121.5.651.

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Hasegawa, Yoshihiro. « Phakomatosis Pigmentovascularis Type IVa ». Archives of Dermatology 121, n^o 5 (1 mai 1985) : 651. http://dx.doi.org/10.1001/archderm.1985.01660050103025.

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Claret, Laurent, Sylvie Miquel, Natacha Vieille, Dmitri A. Ryjenkov, Mark Gomelsky et Arlette Darfeuille-Michaud. « The Flagellar Sigma Factor FliA Regulates Adhesion and Invasion of Crohn Disease-associated Escherichia coli via a Cyclic Dimeric GMP-dependent Pathway ». Journal of Biological Chemistry 282, n^o 46 (7 septembre 2007) : 33275–83. http://dx.doi.org/10.1074/jbc.m702800200.

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The invasion of intestinal epithelial cells by the Crohn disease-associated adherent-invasive Escherichia coli (AIEC) strain LF82 depends on surface appendages, such as type 1 pili and flagella. The absence of flagella in the AIEC strain LF82 results in a concomitant loss of type 1 pili. Here, we show that flagellar regulators, transcriptional activator FlhD2C2, and sigma factor FliA are involved in the coordination of flagellar and type 1 pili synthesis. In the deletion mutants lacking these regulators, type 1 pili synthesis, adhesion, and invasion were severely decreased. FliA expressed alone in trans was sufficient to restore these defects in both the LF82-ΔflhD and LF82-ΔfliA mutants. We related the loss of type 1 pili to the decreased expression of the FliA-dependent yhjH gene in the LF82-ΔfliA mutant. YhjH is an EAL domain phosphodiesterase involved in degradation of the bacterial second messenger cyclic dimeric GMP (c-di-GMP). Increased expression of either yhjH or an alternative c-di-GMP phosphodiesterase, yahA, partially restored type 1 pili synthesis, adhesion, and invasion in the LF82-ΔfliA mutant. Deletion of the GGDEF domain diguanylate cyclase gene, yaiC, involved in c-di-GMP synthesis in the LF82-ΔfliA mutant also partially restored these defects, whereas overexpression of the c-di-GMP receptor YcgR had the opposite effect. These findings show that in the AIEC strain LF82, FliA is a key regulatory component linking flagellar and type 1 pili synthesis and that its effect on type 1 pili is mediated, at least in part, via a c-di-GMP-dependent pathway.

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Leang, Ching, Xinlei Qian, Tünde Mester et Derek R. Lovley. « Alignment of the c-Type Cytochrome OmcS along Pili of Geobacter sulfurreducens ». Applied and Environmental Microbiology 76, n^o 12 (16 avril 2010) : 4080–84. http://dx.doi.org/10.1128/aem.00023-10.

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ABSTRACT Immunogold localization revealed that OmcS, a cytochrome that is required for Fe(III) oxide reduction by Geobacter sulfurreducens, was localized along the pili. The apparent spacing between OmcS molecules suggests that OmcS facilitates electron transfer from pili to Fe(III) oxides rather than promoting electron conduction along the length of the pili.

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De La Fuente, Leonardo, Thomas J. Burr et Harvey C. Hoch. « Autoaggregation of Xylella fastidiosa Cells Is Influenced by Type I and Type IV Pili ». Applied and Environmental Microbiology 74, n^o 17 (18 juillet 2008) : 5579–82. http://dx.doi.org/10.1128/aem.00995-08.

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ABSTRACT Autoaggregation of widely dispersed Xylella fastidiosa cells into compact cell masses occurred over a period of hours following 7 to 11 days of growth in microfluidic chambers. Studies involving the use of mutants defective in polarly positioned type I (fimA-negative), type IV (pilB-negative), or both type I and IV (fimA- and pilO-negative) pili revealed the importance and role of pili in the autoaggregation process.

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Wall, Daniel, Samuel S. Wu et Dale Kaiser. « Contact Stimulation of Tgl and Type IV Pili inMyxococcus xanthus ». Journal of Bacteriology 180, n^o 3 (1 février 1998) : 759–61. http://dx.doi.org/10.1128/jb.180.3.759-761.1998.

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ABSTRACT Myxococcus xanthus tgl mutants lack social motility and type IV pili but can be transiently stimulated to swarm and to make pili by contacting tgl + cells. The absence of pili in tgl mutants is shown not to be due to the absence of pilin. The rate of pilus elongation after Tgl stimulation is shown to be similar to the rate of pilus elongation in wild-type cells, using a new more rapid assay for stimulation.

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Meng, Yizhi, Yaxin Li, Cheryl D. Galvani, Guixia Hao, James N. Turner, Thomas J. Burr et H. C. Hoch. « Upstream Migration of Xylella fastidiosa via Pilus-Driven Twitching Motility ». Journal of Bacteriology 187, n^o 16 (15 août 2005) : 5560–67. http://dx.doi.org/10.1128/jb.187.16.5560-5567.2005.

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ABSTRACT Xylella fastidiosa is a xylem-limited nonflagellated bacterium that causes economically important diseases of plants by developing biofilms that block xylem sap flow. How the bacterium is translocated downward in the host plant's vascular system against the direction of the transpiration stream has long been a puzzling phenomenon. Using microfabricated chambers designed to mimic some of the features of xylem vessels, we discovered that X. fastidiosa migrates via type IV-pilus-mediated twitching motility at speeds up to 5 μm min−1 against a rapidly flowing medium (20,000 μm min−1). Electron microscopy revealed that there are two length classes of pili, long type IV pili (1.0 to 5.8 μm) and short type I pili (0.4 to 1.0 μm). We further demonstrated that two knockout mutants (pilB and pilQ mutants) that are deficient in type IV pili do not twitch and are inhibited from colonizing upstream vascular regions in planta. In addition, mutants with insertions in pilB or pilQ (possessing type I pili only) express enhanced biofilm formation, whereas a mutant with an insertion in fimA (possessing only type IV pili) is biofilm deficient.

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Vignon, Guillaume, Rolf Köhler, Eric Larquet, Stéphanie Giroux, Marie-Christine Prévost, Pascal Roux et Anthony P. Pugsley. « Type IV-Like Pili Formed by the Type II Secreton : Specificity, Composition, Bundling, Polar Localization, and Surface Presentation of Peptides ». Journal of Bacteriology 185, n^o 11 (1 juin 2003) : 3416–28. http://dx.doi.org/10.1128/jb.185.11.3416-3428.2003.

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ABSTRACT The secreton or type II secretion machinery of gram-negative bacteria includes several type IV pilin-like proteins (the pseudopilins) that are absolutely required for secretion. We previously reported the presence of a bundled pilus composed of the pseudopilin PulG on the surface of agar-grown Escherichia coli K-12 cells expressing the Klebsiella oxytoca pullulanase (Pul) secreton genes at high levels (N. Sauvonnet, G. Vignon, A. P. Pugsley, and P. Gounon, EMBO J. 19:2221-2228, 2000). We show here that PulG is the only pseudopilin in purified pili and that the phenomenon is not restricted to the Pul secreton reconstituted in E. coli or to PulG. For example, high-level expression of the endogenous E. coli gsp secreton genes caused production of bundled pili composed of the pseudopilin GspG, and the Pul secreton was able to form pili composed of PulG-like proteins from secreton systems of other bacteria. PulG derivatives in which the C terminus was extended by the addition of eight different peptides were also assembled into pili and functioned in secretion. Three of the C-terminal peptides were shown to be exposed along the entire length of the assembled pili. Hence, the C terminus of PulG may represent a permissive site for the insertion of immunogenic epitopes or other peptide sequences. One of these PulG variants, with a six-histidine tag at its C terminus, formed nonpolar, nonbundled pili, suggesting that bundle formation and polar localization are not correlated with the ability of PulG to function in secretion. We propose that the PulG pilus is an artifactual manifestation of a periplasmic “pseudopilus” and that cycles of pseudopilus extension and retraction within the periplasm propel pullulanase through secretin channels in the outer membrane. Abnormally long pili that extend beyond the outer membrane are produced only when pilus length control and retraction are deregulated by overproduction of the major pseudopilus subunit (PulG).

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Jacobsen, Theis, Benjamin Bardiaux, Olivera Francetic, Nadia Izadi-Pruneyre et Michael Nilges. « Structure and function of minor pilins of type IV pili ». Medical Microbiology and Immunology 209, n^o 3 (29 novembre 2019) : 301–8. http://dx.doi.org/10.1007/s00430-019-00642-5.

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AbstractType IV pili are versatile and highly flexible fibers formed on the surface of many Gram-negative and Gram-positive bacteria. Virulence and infection rate of several pathogenic bacteria, such as Neisseria meningitidis and Pseudomonas aeruginosa, are strongly dependent on the presence of pili as they facilitate the adhesion of the bacteria to the host cell. Disruption of the interactions between the pili and the host cells by targeting proteins involved in this interaction could, therefore, be a treatment strategy. A type IV pilus is primarily composed of multiple copies of protein subunits called major pilins. Additional proteins, called minor pilins, are present in lower abundance, but are essential for the assembly of the pilus or for its specific functions. One class of minor pilins is required to initiate the formation of pili, and may form a complex similar to that identified in the related type II secretion system. Other, species-specific minor pilins in the type IV pilus system have been shown to promote additional functions such as DNA binding, aggregation and adherence. Here, we will review the structure and the function of the minor pilins from type IV pili.

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Liu, Xing, Pier-Luc Tremblay, Nikhil S. Malvankar, Kelly P. Nevin, Derek R. Lovley et Madeline Vargas. « A Geobacter sulfurreducens Strain Expressing Pseudomonas aeruginosa Type IV Pili Localizes OmcS on Pili but Is Deficient in Fe(III) Oxide Reduction and Current Production ». Applied and Environmental Microbiology 80, n^o 3 (2 décembre 2013) : 1219–24. http://dx.doi.org/10.1128/aem.02938-13.

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ABSTRACTThe conductive pili ofGeobacterspecies play an important role in electron transfer to Fe(III) oxides, in long-range electron transport through current-producing biofilms, and in direct interspecies electron transfer. Although multiple lines of evidence have indicated that the pili ofGeobacter sulfurreducenshave a metal-like conductivity, independent of the presence ofc-type cytochromes, this claim is still controversial. In order to further investigate this phenomenon, a strain ofG. sulfurreducens, designated strain PA, was constructed in which the gene for the native PilA, the structural pilin protein, was replaced with the PilA gene ofPseudomonas aeruginosaPAO1. Strain PA expressed and properly assembledP. aeruginosaPilA subunits into pili and exhibited a profile of outer surfacec-type cytochromes similar to that of a control strain expressing theG. sulfurreducensPilA. Surprisingly, the strain PA pili were decorated with thec-type cytochrome OmcS in a manner similar to the control strain. However, the strain PA pili were 14-fold less conductive than the pili of the control strain, and strain PA was severely impaired in Fe(III) oxide reduction and current production. These results demonstrate that the presence of OmcS on pili is not sufficient to confer conductivity to pili and suggest that there are unique structural features of theG. sulfurreducensPilA that are necessary for conductivity.

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Karuppiah, Vijaykumar, et Jeremy P. Derrick. « Type IV pili—a numbers game ». EMBO Journal 33, n^o 16 (25 juin 2014) : 1732–34. http://dx.doi.org/10.15252/embj.201489096.

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Kåhrström, Christina Tobin. « Type IV pili function as mechanosensors ». Nature Reviews Microbiology 13, n^o 7 (15 juin 2015) : 399. http://dx.doi.org/10.1038/nrmicro3517.

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Mattick, John S. « Type IV Pili and Twitching Motility ». Annual Review of Microbiology 56, n^o 1 (octobre 2002) : 289–314. http://dx.doi.org/10.1146/annurev.micro.56.012302.160938.

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Ruiz-Villaverde, R., A. Villanova-Mateu, R. Ortega del Olmo et D. Sanchez-Cano. « Pseudomonilethrix type II and pili bifurcati ». Journal of the European Academy of Dermatology and Venereology 20, n^o 7 (19 juillet 2006) : 889–90. http://dx.doi.org/10.1111/j.1468-3083.2006.01564.x.

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Nudleman, Eric, et Dale Kaiser. « Pulling Together with Type IV Pili ». Journal of Molecular Microbiology and Biotechnology 7, n^o 1-2 (2004) : 52–62. http://dx.doi.org/10.1159/000077869.

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Pelicic, Vladimir. « Type IV pili : e pluribus unum ? » Molecular Microbiology 68, n^o 4 (mai 2008) : 827–37. http://dx.doi.org/10.1111/j.1365-2958.2008.06197.x.

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Nassif, Xavier, Michaël Marceau, Céline Pujol, Bénédicte Pron, Jean-Luc Beretti et Muhamed-Kheir Taha. « Type-4 pili and meningococcal adhesiveness ». Gene 192, n^o 1 (juin 1997) : 149–53. http://dx.doi.org/10.1016/s0378-1119(96)00802-5.

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Weir, Susan, Li-Wei Lee et Carl F. Marrs. « Type-4 pili of Kingella denitrificans ». Gene 192, n^o 1 (juin 1997) : 171–76. http://dx.doi.org/10.1016/s0378-1119(96)00828-1.

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Wall, Daniel, et Dale Kaiser. « Type IV pili and cell motility ». Molecular Microbiology 32, n^o 1 (avril 1999) : 01–10. http://dx.doi.org/10.1046/j.1365-2958.1999.01339.x.

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Tala, Lorenzo, Xavier Pierrat et Alexandre Persat. « Bacterial Mechanosensing with Type IV Pili ». Biophysical Journal 114, n^o 3 (février 2018) : 3a. http://dx.doi.org/10.1016/j.bpj.2017.11.045.

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Jenkins, A. Toby A., Angus Buckling, Marsha McGhee et Richard H. ffrench-Constant. « Surface plasmon resonance shows that type IV pili are important in surface attachment by Pseudomonas aeruginosa ». Journal of The Royal Society Interface 2, n^o 3 (16 mai 2005) : 255–59. http://dx.doi.org/10.1098/rsif.2005.0030.

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Type IV pili have been shown to play a role in the early stages of bacterial biofilm formation, but not in initial bacterial attachment. Here, using the surface analytical technique, surface plasmon resonance (SPR), we follow the attachment of the bacterium Pseudomonas aeruginosa in real time. In contrast to previous studies, we show that type IV pili mutants are defective in attachment. Both mutants lacking pili ( pilA ), and those possessing an overabundance of pili ( pilT ), showed reduced SPR measured attachment compared with the wild-type PAO1 strain. Both pil mutants also showed reduced pathogenicity in a model insect host, as measured by percentage mortality after 24 h. SPR revealed differences in the kinetics of attachment between pilA and pilT , differences obscured by endpoint assays using crystal violet stain. These results highlight the power of SPR in monitoring bacterial attachment in real time and also demonstrate an additional role for type IV pili beyond bacterial aggregation and micro-colony formation.

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