Relevant bibliographies by topics / Outer membrane protein

Academic literature on the topic 'Outer membrane protein'

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Published: 4 June 2021
Last updated: 9 March 2023

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Journal articles on the topic "Outer membrane protein"

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Hazlett, Karsten R. O., David L. Cox, Marc Decaffmeyer, Michael P. Bennett, Daniel C. Desrosiers, Carson J. La Vake, Morgan E. La Vake, et al. "TP0453, a Concealed Outer Membrane Protein of Treponema pallidum, Enhances Membrane Permeability." Journal of Bacteriology 187, no. 18 (September 15, 2005): 6499–508. http://dx.doi.org/10.1128/jb.187.18.6499-6508.2005.

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ABSTRACT The outer membrane of Treponema pallidum, the noncultivable agent of venereal syphilis, contains a paucity of protein(s) which has yet to be definitively identified. In contrast, the outer membranes of gram-negative bacteria contain abundant immunogenic membrane-spanning β-barrel proteins mainly involved in nutrient transport. The absence of orthologs of gram-negative porins and outer membrane nutrient-specific transporters in the T. pallidum genome predicts that nutrient transport across the outer membrane must differ fundamentally in T. pallidum and gram-negative bacteria. Here we describe a T. pallidum outer membrane protein (TP0453) that, in contrast to all integral outer membrane proteins of known structure, lacks extensive β-sheet structure and does not traverse the outer membrane to become surface exposed. TP0453 is a lipoprotein with an amphiphilic polypeptide containing multiple membrane-inserting, amphipathic α-helices. Insertion of the recombinant, nonlipidated protein into artificial membranes results in bilayer destabilization and enhanced permeability. Our findings lead us to hypothesize that TP0453 is a novel type of bacterial outer membrane protein which may render the T. pallidum outer membrane permeable to nutrients while remaining inaccessible to antibody.
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Ishikawa, Daigo, Hayashi Yamamoto, Yasushi Tamura, Kaori Moritoh, and Toshiya Endo. "Two novel proteins in the mitochondrial outer membrane mediate β-barrel protein assembly." Journal of Cell Biology 166, no. 5 (August 23, 2004): 621–27. http://dx.doi.org/10.1083/jcb.200405138.

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Mitochondrial outer and inner membranes contain translocators that achieve protein translocation across and/or insertion into the membranes. Recent evidence has shown that mitochondrial β-barrel protein assembly in the outer membrane requires specific translocator proteins in addition to the components of the general translocator complex in the outer membrane, the TOM40 complex. Here we report two novel mitochondrial outer membrane proteins in yeast, Tom13 and Tom38/Sam35, that mediate assembly of mitochondrial β-barrel proteins, Tom40, and/or porin in the outer membrane. Depletion of Tom13 or Tom38/Sam35 affects assembly pathways of the β-barrel proteins differently, suggesting that they mediate different steps of the complex assembly processes of β-barrel proteins in the outer membrane.
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Mayer, A., R. Lill, and W. Neupert. "Translocation and insertion of precursor proteins into isolated outer membranes of mitochondria." Journal of Cell Biology 121, no. 6 (June 15, 1993): 1233–43. http://dx.doi.org/10.1083/jcb.121.6.1233.

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Nuclear-encoded proteins destined for mitochondria must cross the outer or both outer and inner membranes to reach their final sub-mitochondrial locations. While the inner membrane can translocate preproteins by itself, it is not known whether the outer membrane also contains an endogenous protein translocation activity which can function independently of the inner membrane. To selectively study the protein transport into and across the outer membrane of Neurospora crassa mitochondria, outer membrane vesicles were isolated which were sealed, in a right-side-out orientation, and virtually free of inner membranes. The vesicles were functional in the insertion and assembly of various outer membrane proteins such as porin, MOM19, and MOM22. Like with intact mitochondria, import into isolated outer membranes was dependent on protease-sensitive surface receptors and led to correct folding and membrane integration. The vesicles were also capable of importing a peripheral component of the inner membrane, cytochrome c heme lyase (CCHL), in a receptor-dependent fashion. Thus, the protein translocation machinery of the outer mitochondrial membrane can function as an independent entity which recognizes, inserts, and translocates mitochondrial preproteins of the outer membrane and the intermembrane space. In contrast, proteins which have to be translocated into or across the inner membrane were only specifically bound to the vesicles, but not imported. This suggests that transport of such proteins involves the participation of components of the intermembrane space and/or the inner membrane, and that in these cases the outer membrane translocation machinery has to act in concert with that of the inner membrane.
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Dhar, Rik, and Joanna SG Slusky. "Outer membrane protein evolution." Current Opinion in Structural Biology 68 (June 2021): 122–28. http://dx.doi.org/10.1016/j.sbi.2021.01.002.

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Slusky, Joanna SG. "Outer membrane protein design." Current Opinion in Structural Biology 45 (August 2017): 45–52. http://dx.doi.org/10.1016/j.sbi.2016.11.003.

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Murcha, Monika W., Dina Elhafez, A. Harvey Millar, and James Whelan. "The C-terminal Region of TIM17 Links the Outer and Inner Mitochondrial Membranes inArabidopsisand Is Essential for Protein Import." Journal of Biological Chemistry 280, no. 16 (February 18, 2005): 16476–83. http://dx.doi.org/10.1074/jbc.m413299200.

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The translocase of the inner membrane 17 (AtTIM17-2) protein fromArabidopsishas been shown to link the outer and inner mitochondrial membranes. This was demonstrated by several approaches: (i)In vitroorganelle import assays indicated the importedAtTIM17-2 protein remained protease accessible in the outer membrane when inserted into the inner membrane. (ii) N-terminal and C-terminal tagging indicated that it was the C-terminal region that was located in the outer membrane. (iii) Antibodies raised to the C-terminal 100 amino acids recognize a 31-kDa protein from purified mitochondria, but cross-reactivity was abolished when mitochondria were protease-treated to remove outer membrane-exposed proteins. Antibodies toAtTIM17-2 inhibited import of proteins via the general import pathway into outer membrane-ruptured mitochondria, but did not inhibit protein import via the carrier import pathway. Together these results indicate that the C-terminal region ofAtTIM17-2 is exposed on the outer surface of the outer membrane, and the C-terminal region is essential for protein import into mitochondria.
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Hoffmann, Juliane J., and Thomas Becker. "Crosstalk between Mitochondrial Protein Import and Lipids." International Journal of Molecular Sciences 23, no. 9 (May 9, 2022): 5274. http://dx.doi.org/10.3390/ijms23095274.

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Mitochondria import about 1000 precursor proteins from the cytosol. The translocase of the outer membrane (TOM complex) forms the major entry site for precursor proteins. Subsequently, membrane-bound protein translocases sort the precursor proteins into the outer and inner membrane, the intermembrane space, and the matrix. The phospholipid composition of mitochondrial membranes is critical for protein import. Structural and biochemical data revealed that phospholipids affect the stability and activity of mitochondrial protein translocases. Integration of proteins into the target membrane involves rearrangement of phospholipids and distortion of the lipid bilayer. Phospholipids are present in the interface between subunits of protein translocases and affect the dynamic coupling of partner proteins. Phospholipids are required for full activity of the respiratory chain to generate membrane potential, which in turn drives protein import across and into the inner membrane. Finally, outer membrane protein translocases are closely linked to organellar contact sites that mediate lipid trafficking. Altogether, intensive crosstalk between mitochondrial protein import and lipid biogenesis controls mitochondrial biogenesis.
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Court, Deborah A., Roland Lill, and Walter Neupert. "The protein import apparatus of the mitochondrial outer membrane." Canadian Journal of Botany 73, S1 (December 31, 1995): 193–97. http://dx.doi.org/10.1139/b95-245.

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The majority of proteins within mitochondria are synthesized on cytosolic ribosomes and imported into the organelles. Protein complexes in the mitochondrial outer membrane harbour both the receptors that recognize these preproteins, and a translocation pore. These "receptor complexes" are the entry points for most preproteins, which are subsequently targeted to their final submitochondrial locations. The outer membrane complexes cooperate with the import machinery of the inner membrane to target preproteins to the inner membrane itself, the matrix, or, in some cases, to the intermembrane space. In isolated outer membranes, these complexes are capable of accurately importing preproteins destined for the outer membrane. Our current understanding of the composition, function, and biogenesis of these outer membrane receptor complexes is the focus of this article. Key words: mitochondria, outer membrane, protein import, receptors.
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Pon, L., T. Moll, D. Vestweber, B. Marshallsay, and G. Schatz. "Protein import into mitochondria: ATP-dependent protein translocation activity in a submitochondrial fraction enriched in membrane contact sites and specific proteins." Journal of Cell Biology 109, no. 6 (December 1, 1989): 2603–16. http://dx.doi.org/10.1083/jcb.109.6.2603.

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To identify the membrane regions through which yeast mitochondria import proteins from the cytoplasm, we have tagged these regions with two different partly translocated precursor proteins. One of these was bound to the mitochondrial surface of ATP-depleted mitochondria and could subsequently be chased into mitochondria upon addition of ATP. The other intermediate was irreversibly stuck across both mitochondrial membranes at protein import sites. Upon subfraction of the mitochondria, both intermediates cofractionated with membrane vesicles whose buoyant density was between that of inner and outer membranes. When these vesicles were prepared from mitochondria containing the chaseable intermediate, they internalized it upon addition of ATP. A non-hydrolyzable ATP analogue was inactive. This vesicle fraction contained closed, right-side-out inner membrane vesicles attached to leaky outer membrane vesicles. The vesicles contained the mitochondrial binding sites for cytoplasmic ribosomes and contained several mitochondrial proteins that were enriched relative to markers of inner or outer membranes. By immunoelectron microscopy, two of these proteins were concentrated at sites where mitochondrial inner and outer membranes are closely apposed. We conclude that these vesicles contain contact sites between the two mitochondrial membranes, that these sites are the entry point for proteins into mitochondria, and that the isolated vesicles are still translocation competent.
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Braun, Volkmar. "The Outer Membrane Took Center Stage." Annual Review of Microbiology 72, no. 1 (September 8, 2018): 1–24. http://dx.doi.org/10.1146/annurev-micro-090817-062156.

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My interest in membranes was piqued during a lecture series given by one of the founders of molecular biology, Max Delbrück, at Caltech, where I spent a postdoctoral year to learn more about protein chemistry. That general interest was further refined to my ultimate research focal point—the outer membrane of Escherichia coli—through the influence of the work of Wolfhard Weidel, who discovered the murein (peptidoglycan) layer and biochemically characterized the first phage receptors of this bacterium. The discovery of lipoprotein bound to murein was completely unexpected and demonstrated that the protein composition of the outer membrane and the structure and function of proteins could be unraveled at a time when nothing was known about outer membrane proteins. The research of my laboratory over the years covered energy-dependent import of proteinaceous toxins and iron chelates across the outer membrane, which does not contain an energy source, and gene regulation by iron, including transmembrane transcriptional regulation.
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Dissertations / Theses on the topic "Outer membrane protein"

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Barlow, Ann Katherine. "Neisseria meningitidis : the class 1 outer membrane protein." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280415.

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McBride, Heidi May. "Protein import into and across the mitochondrial outer membrane." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40395.

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Protein import into the mitochondria is a result of a series of sequential binding interactions between a mitochondrial targeting signal and the translocation machinery of both mitochondrial membranes. The targeting signals contained within protein of the outer membrane are distinct from those which target proteins to other subcompartments. The transmembrane domain of the yeast outer membrane receptor protein yTom70 is capable of both targeting and inserting the protein into the outer membrane. The efficiency of this process is increased by the addition of a positively-charged region preceding the transmembrane region. These two structural domains co-operate to form a signal-anchor sequence selective for the outer membrane, since this is the first membrane encountered by the targeting signal.
Consistent with this model, the signal-anchor sequence of the outer membrane protein yTom70 is also capable of importing into the inner membrane of mitochondria when the outer membrane is selectively removed. Import into the inner membrane requires the presence of an electrochemical potential across the lipid bilayer. Import proceeds in the absence of $ Delta Psi$ only when constructs are used which lack the positively-charged amino terminal region of the signal-anchor sequence. These results suggest that the positively-charged presequence leads the transmembrane domain into the import machinery and that $ Delta Psi$ is required to clear this region in order that the distal transmembrane region can enter the translocation pathway.
The charged N-terminal 10 residues of yTom70 are incapable of directing import into intact mammalian mitochondria, however, are able to efficiently direct import into the matrix of yeast mitochondria or mammalian mitoplasts. This potentially cryptic signal is excluded from intact mammalian mitochondria due to the presence of the receptor protein Tom20, since replacement of yeast Tom20 with mammalian Tom20 confers the mammalian phenotype onto yeast. These results suggest that receptor proteins may also have the ability to screen potentially cryptic signals from distal components of the outer and inner membrane translocation machinery.
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See, Sarah Bihui. "Outer membrane protein immunity to Pasteurella pneumotropica and the interaction of allergy." University of Western Australia. School of Paediatrics and Child Health, 2010. http://theses.library.uwa.edu.au/adt-WU2010.0103.

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[Truncated abstract] Infectious and allergic diseases of the respiratory tract are major contributors to global mortality, morbidity and economic burden. Bacterial infections such as pneumonia and otitis media are important diseases, especially in children, while allergic diseases such as asthma and allergic rhinitis afflict up to 30% of the world's population. A confounding aspect of respiratory disease is the evidence of a complex relationship between respiratory allergy and respiratory infection, with infection suggested to both promote and prevent the pathogenesis of allergic disease. Additionally, allergy is a risk factor for bacterial infection such as otitis media, pneumonia and sinusitis, while respiratory infection can exacerbate allergic symptoms. Given the burden of bacterial respiratory disease and respiratory allergy, the development of preventative treatments for these diseases is needed and will benefit from clearer knowledge of the underlying immune mechanisms. This thesis aimed to to extend current knowledge by using Pasteurella pneumotropica, a similar bacteria to the human pathogen nontypeable Haemophilus influenzae (NTHi), to study respiratory infection and protective anti-outer membrane protein (OMP) immunity as well as the interaction of respiratory infection and allergic inflammation. Homologues of the important NTHi vaccine candidates P4, P6, P26 and D15 were found to be encoded by P. pneumotropica and a high level of amino acid sequence identity was noted between the different P. pneumotropica strains, as well as between other Pasteurellaceae members. ... In contrast, anti-P6his serum antibodies transferred to naïve mice did not confer protection. These results suggested that T-cell–mediated mechanisms were involved in P6his-mediated protection, and showed that the P. pneumotropcia model was useful for elucidating protective mechansims. The interaction of P. pneumotropica infection and papain-induced allergy was studied to investigate immune mechanisms underlying respiratory infection and allergy. Mice with ongoing allergic inflammation were intranasally challenged with bacteria and exhibited reduced pulmonary bacterial numbers, prolonged eosinophilia in the lungs and the induction of Th2 cytokines in the BALF, compared to nonallergic, infected mice. This suggested a protective role for allergic inflammation in this model. The effect of papaininduced inflammation on mice colonised by P. pneumotropica was also examined and allergic inflammation appeared to worsen infection in colonised mice. This suggested that allergic inflammation may also have a role in promoting infection in this model. In conclusion, this thesis explored mechanisms involved in vaccine-mediated immunity and the interaction of respiratory infection and allergy using a P. pneumotropica infection in its natural host. It was shown that intranasally administered recombinant P6 and P4 protected mice from lung infection, which justifies the inclusion of these OMPs as NTHi vaccine candidates. Additionally, it was demonstrated that the interaction of allergy and respiratory infection modulated immune responses. Overall, these results emphasize that a clearer understanding of the complex mechanisms underlying these interactions is required, and may be aided by the development of suitable animal models.
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Juodeikis, Rokas. "Engineering membranes in Escherichia coli : the magnetosome, LemA protein family and outer membrane vesicles." Thesis, University of Kent, 2016. https://kar.kent.ac.uk/61062/.

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Magnetosomes are membranous organelles found in magnetotactic bacteria (MTB). The organelle consist of ferromagnetic crystals housed within a lipid bilayer chained together by an actin-like filament and allows MTB to orient within magnetic fields. The genetic information required to produce these organelles has been linked to four different operons, encoding for 30 genes. These membranous organelles and the magnetic minerals housed within have various biotechnological applications, therefore enhanced recombinant production of such structures in a model organism holds significant potential. The research described in this thesis is focuses on the production of recombinant magnetosomes in the model organism Escherichia coli. Cloning the genes involved in the generation of the organelle individually or in various combinations resulted in the construction of over 100 different plasmids, compatible with the model organism. SDS-PAGE and electron microscopy analysis was used to characterise E. coli cells harbouring these constructs. The observation of electron dense particles, arranged in a chain structure, show that magnetosome generation in the model organism is possible, but is highly dependent on the growth conditions used. The need for specific growth conditions is later backed up by the analysis of the maturation of the cytochrome c proteins involved in magnetosome biomineralisation, which can only be correctly processed under certain conditions. Individual production of two different magnetosome proteins, MamQ or MamY, allowed the generation of various membranous structures in E. coli observed in 48.9% and 56.2% of the whole population of cells respectively. Combinations of these with MamI, MamL or MamB in a variety of combinations led to a variation in the phenotype observed. Bioinformatics analysis of MamQ led to the discovery of a novel membrane restructuring protein family, the LemA protein family, present in a broad range of bacteria. Four different LemA proteins from Bacillus megaterium, Clostridium kluyveri, Brucella melitensis or Pseudomonas aeruginosa were then produced in E. coli and the analysis of the resulting strains revealed the presence of novel intracellular membranous structures which vary in size, form and localisation. Furthermore, when attempts were made to target these proteins for the modification of the outer membrane, a mechanism for increased outer membrane vesicle generation was serendipitously discovered and different effects of these proteins were once again observed. Together, the results described shows good evidence for recombinant magnetosome production in E. coli and opens a new avenue of membrane engineering in this commonly used organism. Such membranous structures have various biotechnological applications, such as enhanced metabolic engineering potential or specialised lipid vesicle production.
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Menon, Sailesh. "Characterization of a Fusobacterium necrophorum subspecies necrophorum outer membrane protein." Kansas State University, 2014. http://hdl.handle.net/2097/18128.

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Master of Science
Department of Biomedical Sciences
Sanjeev K. Narayanan
Fusobacterium necrophorum is an anaerobic Gram-negative non spore forming rod shaped bacteria that is a normal inhabitant of the alimentary tract of humans and animals. Two subspecies of F. necrophorum have been recognized- subspecies necrophorum and subspecies funduliforme. Subspecies necrophorum is an opportunistic pathogen in animals causing diseases such as bovine hepatic abscesses and sheep foot rot while as subspecies funduliforme is linked with human oral and hepatic infections such as sore throats, Lemierre’s syndrome and hepatic abscesses. The pathogenic mechanisms of F. necrophorum are complex and are not well understood or defined. Several virulence factors such as leukotoxin, haemolysin, haemagglutinin and adhesin have been described. One of the most important factors in F. necrophorum bacterial pathogenesis is the adhesion of the bacteria to the host cell. The adhesion of the bacteria to the host cell helps it colonize the host tissue and this is followed by intracellular multiplication with dissemination to other tissues, which could ultimately lead to septicemia and death. Bacteria use adhesins which are proteins found in the outer membrane which help them bind with host receptors and this helps with the adhesion of the bacteria to the host cell. Not much is known about F. necrophorum adhesins. Here, we describe and characterize a novel adhesin.
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Shand, Geoffrey H. "Antibiotic resistance and outer membrane protein antigens of Pseudomonas aeruginosa." Thesis, Aston University, 1985. http://publications.aston.ac.uk/12475/.

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Kaye, Elena Cortizas. "The Function of Outer Membrane Protein A (OmpA) in Yersinia pestis." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_theses/58.

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The outer membrane protein OmpA is one of the major outer membrane proteins in many species of bacteria, including the Yersiniae. Our goal was to explore the role of OmpA in Y. pestis. This encompasses the ability of Yersinia to infect and survive within macrophages, as well as to resist antimicrobial compounds. Our laboratory found that a delta ompA mutant is impaired in a macrophage-associated infectivity assay. We also found that OmpA might play a role in the ability of the bacteria to resist antimicrobial peptides, specifically polymyxin B. Aditionally, we assessed the differences in OmpA of Y. pestis and E. coli, and determined that the characteristics we have observed in Y. pestis are unique compared to what has previously been described in E. coli. Our results indicate that Y. pestis OmpA might act through known pathways of antimicrobial resistance such as the PhoPQ two-component regulatory system, although further experiments are needed to determine the precise mechanism of function OmpA. Overall, our project characterizes the different functions of OmpA in Y. pestis, both as a key player in intracellular survival and as a necessary component in conferring resistance to antimicrobial peptides.
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Ferris, Shirley. "Antibody responses to the major outer membrane protein of Chlamydia trachomatis." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295880.

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Schiffrin, Robert. "Roles of periplasmic chaperones and BamA in outer membrane protein folding." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15952/.

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A defining feature of living things is that they have an inside and an outside, and in order for all living cells to survive, whether they are part of a blue whale or a unicellular microscopic organism, they must have mechanisms to mediate exchange with their environment. Food and energy enters the cell, and material must also leave, such as the waste products of metabolism, or virulence factors from pathogenic organisms. Lipid membranes define these boundaries, but it is membrane proteins that mediate the exchange. Although lipid bilayers can self-assemble in vitro, the assembly of complex biological membranes containing proteins requires energy and careful coordination. The work presented in this thesis examines the biogenesis pathway of β-barrel outer membrane proteins (OMPs) in Gram-negative bacteria. OMPs are synthesised on cytosolic ribosomes, translocated across the inner membrane, then chaperoned across the periplasm, before folding and insertion into the OM. While OMPs can fold spontaneously into lipid membranes, this process is too slow to be biologically relevant, so a dedicated folding catalyst, the β-barrel assembly machinery (BAM) complex, is required at the OM. Recent genetic, structural and biochemical investigations have increased our understanding of OMP assembly, but key questions remain, including: How do periplasmic chaperones bind and release OMP substrates? What are the roles and interactions of BAM subunits? What is the molecular mechanism by which BAM folds and inserts OMPs? Here, an assay was developed to monitor OMP folding kinetics in vitro using intrinsic fluorescence in low concentrations of urea (0.24 M). This allowed comparison of the real-time folding behaviour of different OMPs under the same conditions for the first time (Chapter 3). The assay was then successfully extended to include OMP assembly factors, including the periplasmic chaperones Skp and SurA, and BamA, the principal component of the BAM complex, to obtain the following key results: Investigations into the interactions between Skp and OMPs of varying size (tOmpA, PagP, OmpT, OmpF and tBamA) revealed that greater Skp:OMP ratios are required to prevent the folding of 16-stranded OMPs compared with smaller 8-stranded OMPs. Supported by ion mobility spectrometry-mass spectrometry (IMS-MS) data, computer modelling and molecular dynamics simulations, the results imply a new mechanism for Skp chaperone activity involving the coordination of multiple copies of Skp to protect a single substrate from aggregation (Chapter 4). Addition of further folding factors to the assay demonstrated that the model OMP tOmpA can be released and folded from its complex with Skp by BamA, possibly recapitulating an in vivo assembly pathway. BamA consists of a β-barrel membrane-embedded domain and soluble periplasmic domains, and while the release activity was shown to located in the membrane domain, the activity was greatest when full-length BamA was present. By contrast, SurA was not able to release tOmpA from Skp under the conditions employed, arguing against a sequential chaperone model (Chapter 5). Next, kinetic studies were used to investigate the mechanism of OMP folding catalysis by the BAM complex. The effect of hydrophobic mismatch between the BamA β-barrel and the membrane was examined by monitoring the folding of tOmpA into liposomes containing lipids of different chain lengths in the presence or absence of BamA. The results showed that BamA has a greater catalytic effect in lipids with longer chain lengths, with the largest rate enhancement achieved in bilayers with a hydrophobic thickness close to that of the OM. The results establish the importance of hydrophobic mismatch in the mechanism by which OMPs are folded in vivo, which may be influenced by local thinning of the membrane and increases in lipid disorder in the vicinity of the BAM complex (Chapter 5). Finally, based on the results obtained in this project, and consideration of the currently available literature, a new 'barrel elongation' model is proposed for the mechanism of OMP assembly by the BAM complex (Chapter 6). The OMP assembly pathway is an attractive target for novel antibacterials given that it is surface located, highly conserved, and essential in clinically important pathogens. Understanding the molecular mechanisms of OMP biogenesis factors will facilitate the development of drugs targeting this pathway. The work described in this thesis provides new insights into the mechanisms of OMP assembly, using a wide range of biochemical and biophysical techniques, thereby contributing to the development of this fast-moving and fascinating field.
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Huysmans, Gerard Herman Marleen. "On the folding mechanism of the bacterial outer membrane protein PagP." Thesis, University of Leeds, 2008. http://etheses.whiterose.ac.uk/6752/.

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Membrane proteins represent an important class of macromolecules that play critical roles in many biological processes. The energetic principles underlying their stability, however, are not well understood. To address this deficiency, the kinetics and thermodynamics of the folding of the Escherichia coli outer membrane protein PagP were investigated by exploiting the ability of this polypeptide to refold into detergent micelles and into artificial lipid membranes. Investigations using the latter enabled the contributions to the folding process of both the protein sequence and of the bilayer lipid oomposition to be discerned.
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Books on the topic "Outer membrane protein"

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Shand, Geoffrey Harold. Antibiotic resistance and outer membrane protein antigens of Pseudomonas aeruginasa. Birmingham: University of Aston. Department of Pharmaceutical Sciences, 1985.

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Kraak, Wilma A. G. Outer membrane protein typing of Haemophilus influenzae: An epidemiological tool in type b and non-encapsulated strains. Oxford: Oxford Polytechnic, 1990.

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Sun, Frank. Identification of Porphyromonas (Bacteroides) Gingivalis outer membrane proteins that bind to and degrade human matrix proteins. [Toronto: Faculty of Dentistry, University of Toronto, 1992.

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Mortimer, Peter G. S. The role of Esherichia coli outer membrane proteins in determining the accumulation of and susceptibility to antibiotics. Birmingham: University of Birmingham, 1991.

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Maciver, Isobel. The effect of haem limitation and iron restriction on outer membrane proteins and on respiratory systems of non typable Haemophilus influenzae. Birmingham: Aston University. Department of Pharmaceutical Sciences, 1989.

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Characterization of the maltose regulon of Vibrio cholerae: Involvement of maltose in production of outer membrane proteins and secretion of virulence factors. Uppsala: Swedish University of Agricultural Sciences, Dept. of Molecular Genetics, Uppsala Genetic Center, 1993.

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Kania, Stephen Anthony. Isolation and characterization of a 78,000 dalton outer membrane protein of Haemophilus somnus. 1987.

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The 2.05 Å crystal structure of LptB, an essential protein in gram-negative bacterial outer membrane biogenesis. 2011.

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Structural and Functional Relationships in Prokaryotes. Springer, 2004.

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Barton, Larry L. Structural and Functional Relationships in Prokaryotes. Springer London, Limited, 2005.

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Book chapters on the topic "Outer membrane protein"

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Poolman, J. "Outer Membrane Protein Vaccines." In Vaccines, 225–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-59955-2_9.

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Nanda, Vikas, Daniel Hsieh, and Alexander Davis. "Prediction and Design of Outer Membrane Protein–Protein Interactions." In Membrane Proteins, 183–96. Totowa, NJ: Humana Press, 2013. http://dx.doi.org/10.1007/978-1-62703-583-5_10.

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Tommassen, Jan, and Romé Voulhoux. "Biogenesis of Outer Membrane Proteins." In Protein Secretion Pathways in Bacteria, 83–97. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0095-6_5.

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Poolman, Jan T. "Bacterial Outer Membrane Protein Vaccines." In Advances in Experimental Medicine and Biology, 73–77. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4899-1382-1_11.

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Cecil, Jessica D., Natalie Sirisaengtaksin, NEIL M. O'BRIEN-SIMPSON, and Anne Marie Krachler. "Outer Membrane Vesicle-Host Cell Interactions." In Protein Secretion in Bacteria, 201–14. Washington, DC, USA: ASM Press, 2019. http://dx.doi.org/10.1128/9781683670285.ch17.

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Millar, D. G., and G. C. Shore. "Protein Insertion Into The Outer Mitochondrial Membrane." In Molecular Mechanisms of Membrane Traffic, 105–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-662-02928-2_21.

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Grabowicz, Marcin. "Lipoproteins and Their Trafficking to the Outer Membrane." In Protein Secretion in Bacteria, 67–76. Washington, DC, USA: ASM Press, 2019. http://dx.doi.org/10.1128/9781683670285.ch6.

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Tu, Shuh-Long, and Hsou-min Li. "Protein Targeting to the Chloroplast Outer Membrane." In Photosynthesis: Mechanisms and Effects, 3069–73. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-3953-3_719.

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Heckels, J. E., M. Virji, K. Zak, and J. N. Fletcher. "Immunobiology of gonococcal outer membrane protein I." In Gonococci and Meningococci, 369–71. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-1383-7_60.

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Ricci, Dante P., and Thomas J. Silhavy. "Outer Membrane Protein Insertion by the β-barrel Assembly Machine." In Protein Secretion in Bacteria, 91–101. Washington, DC, USA: ASM Press, 2019. http://dx.doi.org/10.1128/9781683670285.ch8.

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Conference papers on the topic "Outer membrane protein"

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Wilkinson, J. M., N. Hack, L. I. Thorsen, and J. A. Thomas. "MONOCLONAL ANTIBODIES RECOGNISING PROTEINS OF THE OUTER AND INNER SURFACE OF THE PLATELET PLASMA MEMBRANE." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644493.

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Platelet membrane preparations can be fractionated into two major subpopulations by free flow electrophoresis and these have been shown to correspond to the plasma membrane and the endoplasmic reticulum of the platelet. The plasma membrane fraction can be shown, by two-dimensional electrophoresis, to contain the major surface glycoproteins together with considerable amounts of actin and actin-associated proteins such as the 250 kDa actin-binding protein (filamin), P235 (talin), myosin, α-actinin and tropomyosin (Hack, N. … Crawford, N., Biochem. J. 222, 235 (1984). These cytoskeletal proteins are associated with the cytoplasmic face of the plasma membrane and probably interact with transmembrane glycoproteins. We have raised monoclonal antibodies to the purified plasma membrane preparation in order to investigate the nature of these glycoprotein-cytoskeletal interactions. In two fusion experiments, out of 804 tested, 104 hybrids secreted antibody to the membrane preparation and of these 24 were selected for further study. Initial assays were by ELISA using either the membrane preparation or whole fixed platelets as the target antigen. The specificity of the antibodies was investigated further by immunoblotting of SDS gels of total platelet proteins prepared under reducing and nonreducing conditions, by immunofluorescence, by immunohisto-chemistry and by crossed immunoelectrophoresis. The majority of the antibodies recognise major surface glycoproteins; of these, four bind to glycoprotein Ib under all conditions examined while another seven recognise the glycoprotein IIb/IIIa complex as detected by crossed immunoelectrophoresis. Three antibodies recognise the actin binding protein and these cross-react with the smooth muscle protein filamin in a number of different species. Further characterisation of these antibodies in both structural and functional terms will be presented.We are grateful to the Smith and Nephew Foundation for financial support for these studies
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Harasztosi, Csaba, Emese Harasztosi, and Anthony W. Gummer. "Membrane recycling at the infranuclear pole of the outer hair cell." In MECHANICS OF HEARING: PROTEIN TO PERCEPTION: Proceedings of the 12th International Workshop on the Mechanics of Hearing. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4939332.

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Pires, Inês, and Miguel Machuqueiro. "pH-dependent permeability of outer membrane protein G: an in silico study." In MOL2NET 2018, International Conference on Multidisciplinary Sciences, 4th edition. Basel, Switzerland: MDPI, 2018. http://dx.doi.org/10.3390/mol2net-04-06077.

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Voigt, W., W. Rabsch, and H. Tschäpe. "Differences in the outer membrane protein pattern of Salmonella typhimurium DT8, DT10 and DT104 strains." In Fourth International Symposium on the Epidemiology and Control of Salmonella and Other Food Borne Pathogens in Pork. Iowa State University, Digital Press, 2001. http://dx.doi.org/10.31274/safepork-180809-201.

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Shen, Dandan, Anchun Cheng, and Mingshu Wang. "Analysis of synonymous codon usage in the outer membrane efflux protein gene of Riemerella anatipestifer." In 2012 5th International Conference on Biomedical Engineering and Informatics (BMEI). IEEE, 2012. http://dx.doi.org/10.1109/bmei.2012.6513098.

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Handayani, Tri, Dadang Priyoatmojo, and Afi Candra Trinugraha. "Outer Membrane Protein (OMP) Profiles of Brucella abortus Local Isolate by SDS-PAGE Procedure." In International Conference on Improving Tropical Animal Production for Food Security (ITAPS 2021). Paris, France: Atlantis Press, 2022. http://dx.doi.org/10.2991/absr.k.220309.006.

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Salamon, Zdzislaw, Gordon Tollin, Angus Macleod, and Ian C. Stevenson. "Spectroscopic studies of membrane protein-lipid bilayer systems deposited on multilayer thin film coatings." In Optical Interference Coatings. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/oic.1998.thd.1.

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Although thin film coatings have been used for many years in optical investigations of biological systems (especially as narrow band light filters), more recent applications of such films in two types of spectroscopic devices, surface plasmon resonance (SPR) and optical waveguides, have provided new biophysical tools for the study of protein-protein and protein-lipid membrane interactions [1]. Although both of these techniques are based on different physical phenomena, the thin film coatings have the same function, i.e. coupling devices in which incident light, under the appropriate optical conditions, can generate an evanescent surface-bound electromagnetic field, which propagates along the interface between the thin film and the emergent dielectric medium in a manner which depends on the interface characteristics. The resulting electric field intensity is concentrated at the outer surface of the film, and diminishes exponentially on both sides of the interface. As a consequence of these properties, it is possible to use SPR and waveguide spectroscopy to probe a few nanometers from the coated surface, a distance well below the wavelength of the light used to generate the evanescent waves, and hence these phenomena have been utilized extensively in studies of surfaces and thin films [for references see 1,2]. Although numerous other optical techniques have also been applied to such systems (e.g. ellipsometry, interferometry, spectrophotometry, and various forms of microscopy), the SPR method has very recently regained its popularity, mainly because of its superior sensitivity, as well as some additional very important advantages over these other methodologies [1,2]. These latter advantages include the following. First, the complete system of measurement is located on the side of the apparatus which is remote from the sample, and thus there is no optical interference from the bulk medium. Second, the outer surface of the sample needs no treatment to increase reflectance, because the necessary high reflectivity is achieved by using total internal reflectance. Third, there are three principal parameters of the resonance that can readily be measured, thereby yielding much more information about the sample and changes within it than the simple interferometric step height used in other sensitive optical techniques.
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McBride, S., M. Ferguson, M. Kelly, K. Hawley, A. Luthra, H. Driscoll, J. Montezuma-Rusca, et al. "P401 Development and Utilization of Antibodies Specific for Extracellular Loops of the Treponema pallidum outer membrane protein BamA (TP0326)." In Abstracts for the STI & HIV World Congress, July 14–17 2021. BMJ Publishing Group Ltd, 2021. http://dx.doi.org/10.1136/sextrans-2021-sti.431.

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"Evaluation of 36 KDa Outer Membrane Protein (OMP’s) by Latex Dri-dot of Salmonella Enterica Serovar Typhi For The Diagnosis Of Typhoid Fever." In April 17-18, 2018 Kyoto (Japan). International Institute of Chemical, Biological and Environmental Engineering, 2018. http://dx.doi.org/10.17758/iicbe1.c0418154.

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Soares, T. A., T. P. Straatsma, Theodore E. Simos, and George Maroulis. "Towards Simulations of Outer Membrane Proteins in Lipopolysaccharide Membranes." In COMPUTATIONAL METHODS IN SCIENCE AND ENGINEERING: Theory and Computation: Old Problems and New Challenges. Lectures Presented at the International Conference on Computational Methods in Science and Engineering 2007 (ICCMSE 2007): VOLUME 1. AIP, 2007. http://dx.doi.org/10.1063/1.2836008.

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Reports on the topic "Outer membrane protein"

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Walian, P. J. Electron crystallography of PhoE porin, an outer membrane, channel- forming protein from E. coli. Office of Scientific and Technical Information (OSTI), November 1989. http://dx.doi.org/10.2172/6365889.

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Palmer, Guy H., Eugene Pipano, Terry F. McElwain, Varda Shkap, and Donald P. Knowles, Jr. Development of a Multivalent ISCOM Vaccine against Anaplasmosis. United States Department of Agriculture, July 1993. http://dx.doi.org/10.32747/1993.7568763.bard.

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Anaplasmosis is an arthropod+borne disease of cattle caused by the rickettsia Anaplasma marginale and an impediment to efficient production of healthy livestock in both Israel and the United States. Our research focuses on development of a recombinant membrane surface protein (MSP) immunogen to replace current vaccines derived from the blood of infected cattle. The risk of widespread transmission of both known and newly emergent pathogens has prevented licensure of live blood-based vaccines in the U.S. and is a major concern for their continued use in Israel. Briefly, we accomplished the following in our BARD supported research: i) characterization of the intramolecular and intermolecular relationships of the native Major Surface Proteins (MSP) in the outer membrane; ii) expression, purification, and epitope characterization of the recombinant MSP-2, MSP-3, MSP-4, and MSP-5 proteins required to construct the recombinant ISCOM; iii) demonstration that the outer membrane-Quil A induces CD4+ T lymphocytes specific for the outer membrane polypeptides; iv) identification of CD4+ T lymphocytes that recognize outer membrane polypeptide epitopes conserved among other wise antigenically distinct strains; v) determination that immunization with the outer membrane-Quil A construct does not affect the ability of ticks to acquire or transmit A. marginale; and vi) demonstration that the outer membrane-Quil A construct induces complete protection against rickettsemia upon homologous challenge and significant protection against challenge with antigenically distinct strains, including tick transmission. Importantly, the level of protection against homologous challenge in the MSP vaccinates was comparable to that induced by live blood-based vaccines and demonstrates that development of a new generation of vaccines is feasible.
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Elbaum, Michael, and Peter J. Christie. Type IV Secretion System of Agrobacterium tumefaciens: Components and Structures. United States Department of Agriculture, March 2013. http://dx.doi.org/10.32747/2013.7699848.bard.

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Objectives: The overall goal of the project was to build an ultrastructural model of the Agrobacterium tumefaciens type IV secretion system (T4SS) based on electron microscopy, genetics, and immunolocalization of its components. There were four original aims: Aim 1: Define the contributions of contact-dependent and -independent plant signals to formation of novel morphological changes at the A. tumefaciens polar membrane. Aim 2: Genetic basis for morphological changes at the A. tumefaciens polar membrane. Aim 3: Immuno-localization of VirB proteins Aim 4: Structural definition of the substrate translocation route. There were no major revisions to the aims, and the work focused on the above questions. Background: Agrobacterium presents a unique example of inter-kingdom gene transfer. The process involves cell to cell transfer of both protein and DNA substrates via a contact-dependent mechanism akin to bacterial conjugation. Transfer is mediated by a T4SS. Intensive study of the Agrobacterium T4SS has made it an archetypal model for the genetics and biochemistry. The channel is assembled from eleven protein components encoded on the B operon in the virulence region of the tumor-inducing plasmid, plus an additional coupling protein, VirD4. During the course of our project two structural studies were published presenting X-ray crystallography and three-dimensional reconstruction from electron microscopy of a core complex of the channel assembled in vitro from homologous proteins of E. coli, representing VirB7, VirB9, and VirB10. Another study was published claiming that the secretion channels in Agrobacterium appear on helical arrays around the membrane perimeter and along the entire length of the bacterium. Helical arrangements in bacterial membranes have since fallen from favor however, and that finding was partially retracted in a second publication. Overall, the localization of the T4SS within the bacterial membranes remains enigmatic in the literature, and we believe that our results from this project make a significant advance. Summary of achievements : We found that polar inflations and other membrane disturbances relate to the activation conditions rather than to virulence protein expression. Activation requires low pH and nutrient-poor medium. These stress conditions are also reflected in DNA condensation to varying degrees. Nonetheless, they must be considered in modeling the T4SS as they represent the relevant conditions for its expression and activity. We identified the T4SS core component VirB7 at native expression levels using state of the art super-resolution light microscopy. This marker of the secretion system was found almost exclusively at the cell poles, and typically one pole. Immuno-electron microscopy identified the protein at the inner membrane, rather than at bridges across the inner and outer membranes. This suggests a rare or transient assembly of the secretion-competent channel, or alternatively a two-step secretion involving an intermediate step in the periplasmic space. We followed the expression of the major secreted effector, VirE2. This is a single-stranded DNA binding protein that forms a capsid around the transferred oligonucleotide, adapting the bacterial conjugation to the eukaryotic host. We found that over-expressed VirE2 forms filamentous complexes in the bacterial cytoplasm that could be observed both by conventional fluorescence microscopy and by correlative electron cryo-tomography. Using a non-retentive mutant we observed secretion of VirE2 from bacterial poles. We labeled the secreted substrates in vivo in order detect their secretion and appearance in the plant cells. However the low transfer efficiency and significant background signal have so far hampered this approach.
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Dunn, Bruce E., Martin J. Blaser, and Edward L. Snyder. Two-Dimensional Gel Electrophoresis and Immunoblotting of Campylobacter Outer Membrane Proteins. Fort Belvoir, VA: Defense Technical Information Center, April 1987. http://dx.doi.org/10.21236/ada265461.

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Blaser, Martin J. Studies of the Outer Membrane Proteins of Campylobacter Jejuni for Vaccine Development. Fort Belvoir, VA: Defense Technical Information Center, November 1991. http://dx.doi.org/10.21236/ada245442.

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Brayton, Kelly A., Varda Shkap, Guy H. Palmer, Wendy C. Brown, and Thea Molad. Control of Bovine Anaplasmosis: Protective Capacity of the MSP2 Allelic Repertoire. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699838.bard.

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Anaplasmosis is an arthropod-borne disease of cattle caused by the rickettsia Anaplasmamarginale and is an impediment to efficient production of healthy livestock in both Israel and the United States. Currently, the only effective vaccines are derived from the blood of infected cattle. The risk of widespread transmission of both known and newly emergent pathogens has prevented licensure of live blood-based vaccines in the U.S. and is a major concern for their continued use in Israel. Consequently, development of a safe, effective vaccine is a high priority. Despite its drawbacks as a live, blood-based vaccine, the Israel vaccine strain protects against disease upon challenge with wild-type A. marginale in extensive experimental trials and during 50 years of deployment in Israel. Field studies in Australia and Argentina indicate that this protection is broadly effective. Thus, to identify antigens for development of a safe and effective recombinant vaccine, we have used a comparative genomics approach by sequencing the Israel vaccine strain and searching for shared surface antigens with sequenced wild-type U.S. strains. We have focused on Msp2, the immune-dominant but antigenically variable surface protein, based on shared structure among strains and demonstration that antibody from cattle immunized with the Israel vaccine strain binds Msp2 from the genetically and geographically distinct U.S. St. Maries strain, consistent with the ability to protect against St. Maries challenge. Importantly, we have defined the full repertoire of Msp2 simple variants encoded by the vaccine strain and hypothesize that a recombinant vaccine encoding this full repertoire will induce protection equivalent to that induced by the live vaccine strain. Any escape from immunity by generation of complex Msp2 variants is predicted to carry a severe fitness cost that prevents high-level bacteremia and disease— consistent with the type of protection induced by the live vaccine strain. We tested the hypothesis that the Msp2 simple variant repertoires in wild-type A. marginale strains are recognized by antibody from cattle immunized with the Israel vaccine strain and that immunization with the vaccine strain Msp2 repertoire can recapitulate the protection provided by the vaccine strain upon challenge with Israel and U.S. strains of A. marginale. Our findings demonstrate that a set of conserved outer membrane proteins are recognized by immune serum from A. centrale vaccinated animals but that this set of proteins does not include Msp2. These findings suggest that “subdominant” immunogens are required for vaccine induced protection.
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Splitter, Gary, and Menachem Banai. Microarray Analysis of Brucella melitensis Pathogenesis. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7709884.bard.

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Original Objectives 1. To determine the Brucella genes that lead to chronic macrophage infection. 2. To identify Brucella genes that contribute to infection. 3. To confirm the importance of Brucella genes in macrophages and placental cells by mutational analysis. Background Brucella spp. is a Gram-negative facultative intracellular bacterium that infects ruminants causing abortion or birth of severely debilitated animals. Brucellosis continues in Israel, caused by B. melitensis despite an intensive eradication campaign. Problems with the Rev1 vaccine emphasize the need for a greater understanding of Brucella pathogenesis that could improve vaccine designs. Virulent Brucella has developed a successful strategy for survival in its host and transmission to other hosts. To invade the host, virulent Brucella establishes an intracellular niche within macrophages avoiding macrophage killing, ensuring its long-term survival. Then, to exit the host, Brucella uses placenta where it replicates to high numbers resulting in abortion. Also, Brucella traffics to the mammary gland where it is secreted in milk. Missing from our understanding of brucellosis is the surprisingly lillie basic information detailing the mechanisms that permit bacterial persistence in infected macrophages (chronic infection) and dissemination to other animals from infected placental cells and milk (acute infection). Microarray analysis is a powerful approach to determine global gene expression in bacteria. The close genomic similarities of Brucella species and our recent comparative genomic studies of Brucella species using our B. melitensis microarray, suqqests that the data obtained from studying B. melitensis 16M would enable understanding the pathogenicity of other Brucella organisms, particularly the diverse B. melitensis variants that confound Brucella eradication in Israel. Conclusions Results from our BARD studies have identified previously unknown mechanisms of Brucella melitensis pathogenesis- i.e., response to blue light, quorum sensing, second messenger signaling by cyclic di-GMP, the importance of genomic island 2 for lipopolysaccharide in the outer bacterial membrane, and the role of a TIR domain containing protein that mimics a host intracellular signaling molecule. Each one of these pathogenic mechanisms offers major steps in our understanding of Brucella pathogenesis. Strikingly, our molecular results have correlated well to the pathognomonic profile of the disease. We have shown that infected cattle do not elicit antibodies to the organisms at the onset of infection, in correlation to the stealth pathogenesis shown by a molecular approach. Moreover, our field studies have shown that Brucella exploit this time frame to transmit in nature by synchronizing their life cycle to the gestation cycle of their host succumbing to abortion in the last trimester of pregnancy that spreads massive numbers of organisms in the environment. Knowing the bacterial mechanisms that contribute to the virulence of Brucella in its host has initiated the agricultural opportunities for developing new vaccines and diagnostic assays as well as improving control and eradication campaigns based on herd management and linking diagnosis to the pregnancy status of the animals. Scientific and Agricultural Implications Our BARD funded studies have revealed important Brucella virulence mechanisms of pathogenesis. Our publication in Science has identified a highly novel concept where Brucella utilizes blue light to increase its virulence similar to some plant bacterial pathogens. Further, our studies have revealed bacterial second messengers that regulate virulence, quorum sensing mechanisms permitting bacteria to evaluate their environment, and a genomic island that controls synthesis of its lipopolysaccharide surface. Discussions are ongoing with a vaccine company for application of this genomic island knowledge in a Brucella vaccine by the U.S. lab. Also, our new technology of bioengineering bioluminescent Brucella has resulted in a spin-off application for diagnosis of Brucella infected animals by the Israeli lab by prioritizing bacterial diagnosis over serological diagnosis.
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Eldar, Avigdor, and Donald L. Evans. Streptococcus iniae Infections in Trout and Tilapia: Host-Pathogen Interactions, the Immune Response Toward the Pathogen and Vaccine Formulation. United States Department of Agriculture, December 2000. http://dx.doi.org/10.32747/2000.7575286.bard.

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In Israel and in the U.S., Streptococcus iniae is responsible for considerable losses in various fish species. Poor understanding of its virulence factors and limited know-how-to of vaccine formulation and administration are the main reasons for the limited efficacy of vaccines. Our strategy was that in order to Improve control measures, both aspects should be equally addressed. Our proposal included the following objectives: (i) construction of host-pathogen interaction models; (ii) characterization of virulence factors and immunodominant antigens, with assessment of their relative importance in terms of protection and (iii) genetic identification of virulence factors and genes, with evaluation of the protective effect of recombinant proteins. We have shown that two different serotypes are involved. Their capsular polysaccharides (CPS) were characterized, and proved to play an important role in immune evasion and in other consequences of the infection. This is an innovative finding in fish bacteriology and resembles what, in other fields, has become apparent in the recent years: S. iniae alters surface antigens. By so doing, the pathogen escapes immune destruction. Immunological assays (agar-gel immunodiffusion and antibody titers) confirmed that only limited cross recognition between the two types occurs and that capsular polysaccharides are immunodominant. Vaccination with purified CPS (as an acellular vaccine) results in protection. In vitro and ex-vivo models have allowed us to unravel additional insights of the host-pathogen interactions. S. iniae 173 (type II) produced DNA fragmentation of TMB-8 cells characteristic of cellular necrosis; the same isolate also prevented the development of apoptosis in NCC. This was determined by finding reduced expression of phosphotidylserine (PS) on the outer membrane leaflet of NCC. NCC treated with this isolate had very high levels of cellular necrosis compared to all other isolates. This cellular pathology was confirmed by observing reduced DNA laddering in these same treated cells. Transmission EM also showed characteristic necrotic cellular changes in treated cells. To determine if the (in vitro) PCD/apoptosis protective effects of #173 correlated with any in vivo activity, tilapia were injected IV with #173 and #164 (an Israeli type I strain). Following injection, purified NCC were tested (in vitro) for cytotoxicity against HL-60 target cells. Four significant observations were made : (i) fish injected with #173 had 100-400% increased cytotoxicity compared to #164 (ii) in vivo activation occurred within 5 minutes of injection; (iii) activation occurred only within the peripheral blood compartment; and (iv) the isolate that protected NCC from apoptosis in vitro caused in vivo activation of cytotoxicity. The levels of in vivo cytotoxicity responses are associated with certain pathogens (pathogen associated molecular patterns/PAMP) and with the tissue of origin of NCC. NCC from different tissue (i.e. PBL, anterior kidney, spleen) exist in different states of differentiation. Random amplified polymorphic DNA (RAPD) analysis revealed the "adaptation" of the bacterium to the vaccinated environment, suggesting a "Darwinian-like" evolution of any bacterium. Due to the selective pressure which has occurred in the vaccinated environment, type II strains, able to evade the protective response elicited by the vaccine, have evolved from type I strains. The increased virulence through the appropriation of a novel antigenic composition conforms with pathogenic mechanisms described for other streptococci. Vaccine efficacy was improved: water-in-oil formulations were found effective in inducing protection that lasted for a period of (at least) 6 months. Protection was evaluated by functional tests - the protective effect, and immunological parameters - elicitation of T- and B-cells proliferation. Vaccinated fish were found to be resistant to the disease for (at least) six months; protection was accompanied by activation of the cellular and the humoral branches.
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