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Thierry Heulin - One of the best experts on this subject based on the ideXlab platform.
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a major Outer Membrane Protein of rahnella aquatilis functions as a porin and root adhesin
Journal of Bacteriology, 1998Co-Authors: Wafa Achouak, Gerard Molle, Jean-marie Pagès, Thierry HeulinAbstract:A 38-kDa major Outer Membrane Protein (OMP) was isolated from the nitrogen-fixing enterobacterium Rahnella aquatilis CF3. This Protein exists as a stable trimer in the presence of 2% sodium dodecyl sulfate at temperatures below 60°C. Single channel experiments showed that this major OMP of R. aquatilis CF3 is able to form pores in the planar lipid Membrane. Two oligonucleotides encoding the N-terminal portion of the 38-kDa OMP and C-terminal portion of OmpC were used to amplify the 38-kDa gene by PCR. The deduced amino acid sequence showed a strong homology with Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, and Serratia marcescens OmpC sequences, except loops L6 and L7, which are postulated to be cell surface exposed. On the basis of the OmpF-PhoE three-dimensional structure, it seems likely that this 38-kDa organizes three 16-strand b-barrel subunits. The relationship between the structure and the double functionality of this Protein as porin and as a root adhesin is discussed. Rahnella aquatilis is a gram-negative enteric bacterium. It was isolated first from drinking and river water (15) and subsequently from human clinical specimens (27) and from the rhizospheres of different plants (5). R. aquatilis CF3 appears to lack fimbriae which could mediate the adhesive mechanism of other bacteria such as Klebsiella sp. (18). Since the R. aquatilis major Outer Membrane Protein (OMP), which has an apparent molecular mass of 38 kDa, was shown to be involved in the adhesion of this organism to wheat roots (1), we consider OMPs to be important in the interaction between this R. aquatilis strain and roots of its host plant. The previously determined N-terminal amino acid sequence (1) indicates that this Protein could be related to the enterobacterial porin family. These major OMPs are organized in a trimeric structure and are usually found in gram-negative bacteria (25). They form three water-filled channels that allow diffusion of small nutrients through the Outer Membrane (24). Porins might also be involved in other functions, such as those described during the invasion of epithelial cells by Salmonella typhimurium (9) and Shigella flexneri (6). We had previously reported that the N-terminal sequence of the major OMP (38 kDa) of R. aquatilis CF3 showed strong homology with enterobacterial porins (1). As this Protein seems to be involved in the adhesion of R. aquatilis to plant roots (1), we sought to characterize it.
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purification and partial characterization of an Outer Membrane Protein involved in the adhesion of rahnella aquatilis to wheat roots
FEMS Microbiology Ecology, 1995Co-Authors: Wafa Achouak, Thierry HeulinAbstract:A 38 kDa major Outer Membrane Protein isolated from the nitrogen-fixing enterobacterium Rahnella aquatilis CF3 showed high affinity for wheat roots in an in vitro adhesion assay. Antibodies directed against the 38 kDa Protein were able to bind to whole cells of R. aquatilis and strongly reduced attachment to wheat roots, suggesting a role in adhesion to and colonization of plant roots. The N-terminal sequence of the 38 kDa Protein revealed a strong homology with enterobacterial porins.
Wafa Achouak - One of the best experts on this subject based on the ideXlab platform.
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a major Outer Membrane Protein of rahnella aquatilis functions as a porin and root adhesin
Journal of Bacteriology, 1998Co-Authors: Wafa Achouak, Gerard Molle, Jean-marie Pagès, Thierry HeulinAbstract:A 38-kDa major Outer Membrane Protein (OMP) was isolated from the nitrogen-fixing enterobacterium Rahnella aquatilis CF3. This Protein exists as a stable trimer in the presence of 2% sodium dodecyl sulfate at temperatures below 60°C. Single channel experiments showed that this major OMP of R. aquatilis CF3 is able to form pores in the planar lipid Membrane. Two oligonucleotides encoding the N-terminal portion of the 38-kDa OMP and C-terminal portion of OmpC were used to amplify the 38-kDa gene by PCR. The deduced amino acid sequence showed a strong homology with Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, and Serratia marcescens OmpC sequences, except loops L6 and L7, which are postulated to be cell surface exposed. On the basis of the OmpF-PhoE three-dimensional structure, it seems likely that this 38-kDa organizes three 16-strand b-barrel subunits. The relationship between the structure and the double functionality of this Protein as porin and as a root adhesin is discussed. Rahnella aquatilis is a gram-negative enteric bacterium. It was isolated first from drinking and river water (15) and subsequently from human clinical specimens (27) and from the rhizospheres of different plants (5). R. aquatilis CF3 appears to lack fimbriae which could mediate the adhesive mechanism of other bacteria such as Klebsiella sp. (18). Since the R. aquatilis major Outer Membrane Protein (OMP), which has an apparent molecular mass of 38 kDa, was shown to be involved in the adhesion of this organism to wheat roots (1), we consider OMPs to be important in the interaction between this R. aquatilis strain and roots of its host plant. The previously determined N-terminal amino acid sequence (1) indicates that this Protein could be related to the enterobacterial porin family. These major OMPs are organized in a trimeric structure and are usually found in gram-negative bacteria (25). They form three water-filled channels that allow diffusion of small nutrients through the Outer Membrane (24). Porins might also be involved in other functions, such as those described during the invasion of epithelial cells by Salmonella typhimurium (9) and Shigella flexneri (6). We had previously reported that the N-terminal sequence of the major OMP (38 kDa) of R. aquatilis CF3 showed strong homology with enterobacterial porins (1). As this Protein seems to be involved in the adhesion of R. aquatilis to plant roots (1), we sought to characterize it.
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purification and partial characterization of an Outer Membrane Protein involved in the adhesion of rahnella aquatilis to wheat roots
FEMS Microbiology Ecology, 1995Co-Authors: Wafa Achouak, Thierry HeulinAbstract:A 38 kDa major Outer Membrane Protein isolated from the nitrogen-fixing enterobacterium Rahnella aquatilis CF3 showed high affinity for wheat roots in an in vitro adhesion assay. Antibodies directed against the 38 kDa Protein were able to bind to whole cells of R. aquatilis and strongly reduced attachment to wheat roots, suggesting a role in adhesion to and colonization of plant roots. The N-terminal sequence of the 38 kDa Protein revealed a strong homology with enterobacterial porins.
Christopher Elkins - One of the best experts on this subject based on the ideXlab platform.
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Outer Membrane Protein dsra is the major fibronectin binding determinant of haemophilus ducreyi
Infection and Immunity, 2008Co-Authors: Isabelle Leduc, Dinitra C White, Igor Nepluev, Robert E Throm, Stanley M Spinola, Christopher ElkinsAbstract:The ability to bind extracellular matrix Proteins is a critical virulence determinant for skin pathogens. Haemophilus ducreyi, the etiological agent of the genital ulcer disease chancroid, binds extracellular matrix components, including fibronectin (FN). We investigated H. ducreyi FN binding and report several important findings about this interaction. First, FN binding by H. ducreyi was greatly increased in bacteria grown on heme and almost completely inhibited by hemoglobin. Second, wild-type strain 35000HP bound significantly more FN than did a dsrA mutant in two different FN binding assays. Third, the expression of dsrA in the dsrA mutant restored FN binding and conferred the ability to bind FN to a non-FN-binding Haemophilus influenzae strain. Fourth, an anti-DsrA monoclonal antibody partially blocked FN binding by H. ducreyi. The hemoglobin receptor, the collagen-binding Protein, the H. ducreyi lectin, the fine-tangle pili, and the Outer Membrane Protein OmpA2 were not involved in H. ducreyi FN binding, since single mutants bound FN as well as the parent strain did. However, the major Outer Membrane Protein may have a minor role in FN binding by H. ducreyi, since a double dsrA momp mutant bound less FN than did the single dsrA mutant. Finally, despite major sequence differences, DsrA Proteins from both class I and class II H. ducreyi strains mediated FN and vitronectin binding. We concluded that DsrA is the major factor involved in FN binding by both classes of H. ducreyi strains.
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serum resistance in haemophilus ducreyi requires Outer Membrane Protein dsra
Infection and Immunity, 2000Co-Authors: Christopher Elkins, John K Morrow, Bonnie OlsenAbstract:Haemophilus ducreyi is resistant to killing by normal serum antibody and complement. We discovered an H. ducreyi Outer Membrane Protein required for expression of serum resistance and termed it DsrA (for “ducreyi serum resistance A”). The dsrA locus was cloned, sequenced, and mutagenized. An isogenic mutant (FX517) of parent strain 35000 was constructed and characterized, and it was found to no longer express dsrA. FX517 was at least 10-fold more serum susceptible than 35000. DsrA was expressed by all strains of H. ducreyi tested, except three naturally occurring, avirulent, serum-sensitive strains. FX517 and the three naturally occurring dsrA-nonexpressing strains were complemented in trans with a plasmid expressing dsrA. All four strains were converted to a serum-resistant phenotype, including two that contained truncated lipooligosaccharide (LOS). Therefore, serum resistance in H. ducreyi does not require expression of full-length LOS but does require expression of dsrA. The dsrA locus from eight additional H. ducreyi strains was sequenced, and the deduced amino acid sequences were more than 85% identical. The major difference between the DsrA Proteins was due to the presence of one, two, or three copies of the heptameric amino acid repeat NTHNINK. These repeats account for the variability in apparent molecular mass of the monomeric form of DsrA (28 to 35 kDa) observed in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Since DsrA is present in virulent strains, is highly conserved, and is required for serum resistance, we speculate that it may be a virulence factor and a potential vaccine candidate.
Bonnie Olsen - One of the best experts on this subject based on the ideXlab platform.
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serum resistance in haemophilus ducreyi requires Outer Membrane Protein dsra
Infection and Immunity, 2000Co-Authors: Christopher Elkins, John K Morrow, Bonnie OlsenAbstract:Haemophilus ducreyi is resistant to killing by normal serum antibody and complement. We discovered an H. ducreyi Outer Membrane Protein required for expression of serum resistance and termed it DsrA (for “ducreyi serum resistance A”). The dsrA locus was cloned, sequenced, and mutagenized. An isogenic mutant (FX517) of parent strain 35000 was constructed and characterized, and it was found to no longer express dsrA. FX517 was at least 10-fold more serum susceptible than 35000. DsrA was expressed by all strains of H. ducreyi tested, except three naturally occurring, avirulent, serum-sensitive strains. FX517 and the three naturally occurring dsrA-nonexpressing strains were complemented in trans with a plasmid expressing dsrA. All four strains were converted to a serum-resistant phenotype, including two that contained truncated lipooligosaccharide (LOS). Therefore, serum resistance in H. ducreyi does not require expression of full-length LOS but does require expression of dsrA. The dsrA locus from eight additional H. ducreyi strains was sequenced, and the deduced amino acid sequences were more than 85% identical. The major difference between the DsrA Proteins was due to the presence of one, two, or three copies of the heptameric amino acid repeat NTHNINK. These repeats account for the variability in apparent molecular mass of the monomeric form of DsrA (28 to 35 kDa) observed in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Since DsrA is present in virulent strains, is highly conserved, and is required for serum resistance, we speculate that it may be a virulence factor and a potential vaccine candidate.
Minjung Park - One of the best experts on this subject based on the ideXlab platform.
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immunization with major Outer Membrane Protein of vibrio vulnificus elicits protective antibodies in a murine model
Journal of Microbiology, 2005Co-Authors: Chorok Jung, Minjung ParkAbstract:: Sera from rabbits were infected with Vibrio vulnificus containing an antibody against major Outer Membrane Protein (MOMP). MOMP of V. vulnificus ATCC 27562 were isolated and purified by Sarkosyl and TritonX-100 dual treatment. Molecular size of MOMP was identified as 36-kDa on 13% SDS-PAGE. The sequence of the first 26 amino acid residues from the N-terminal end of the Protein is AELYNQDGTSLDMGGRAEARLSMKDG , which is a perfect match with OmpU of V. vulnificus CMCP6 and YJ016. MOMP specific IgM and IgG were investigated in groups of mice. The group of mice immunized with MOMP and Alum showed higher levels of IgG2b than the group immunized with only MOMP. Vaccination with MOMP resulted in protective antibodies in the mouse infection experiment.
