title: The Aeromonas dsbA mutation decreased their virulence by triggering type III secretion system but not flagella production.
abstract: Pathogenesis of Aeromonas species have been reported to be associated with virulence factors such as lipopolysaccharides (LPS), bacterial toxins, bacterial secretion systems, flagella, and other surface molecules. Dsb (Disulfide bond) proteins play an important role in catalyzing disulfide bond formation in proteins within the periplasmic space. An A. hydrophila dsbA mutant with attenuated virulence using Dictyostelium amoebae as an alternative host model was identified. The attenuated virulence was tested in other animal models (by intraperitoneal injection in fish and mice) and was correlated with the presence of a defective type III secretion system for the first time in non enteric bacteria. The dsbA mutation was shown in several enteric bacteria to involve the outer membrane secretin. The defect in Aeromonas also seems to involve the outer membrane secretin homologue named AscC. However, unlike what happen in Escherichia coli, no changes in motility or flagella expression were observed for A. hydrophila dsbA mutants. The loss of E. coli motility caused by deletion of dsbA is likely due to defective disulfide bond formation in FlgI, a component of the flagella. No disulfide bond formation in FlgI homologues in Aeromonas flagella biogenesis, either polar or lateral, could be expected according to their amino acid residues sequences.
authors.affiliation: Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, Diagonal 645, 08071 Barcelona, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Vilches
authors.forename: Natalia
authors.initials: N
authors.lastname: Jiménez
authors.forename: Susana
authors.initials: S
authors.lastname: Merino
authors.forename: Juan M
authors.initials: JM
authors.lastname: Tomás
mesh_terms: D016980:Aeromonas hydrophila / Q000235:genetics / Q000472:pathogenicity*; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004023:Dictyostelium / Q000382:microbiology; D004195:Disease Models, Animal; D004220:Disulfides / Q000378:metabolism; D005407:Flagella / Q000502:physiology*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000473:pathology; D008124:Locomotion; D026901:Membrane Transport Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D012633:Secretin / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004220:Disulfides; D026901:Membrane Transport Proteins; D037521:Virulence Factors; D012633:Secretin; C074899:flgI protein, Bacteria