title: Compromised outer membrane integrity in Vibrio cholerae Type II secretion mutants.
abstract: The type II secretion (T2S) system of Vibrio cholerae is a multiprotein complex that spans the cell envelope and secretes proteins important for pathogenesis as well as survival in different environments. Here we report that, in addition to the loss of extracellular secretion, removal or inhibition of expression of the T2S genes, epsC-N, results in growth defects and a broad range of alterations in the outer membrane that interfere with its barrier function. Specifically, the sensitivity to membrane-perturbing agents such as bile salts and the antimicrobial peptide polymyxin B is increased, and periplasmic constituents leak out into the culture medium. As a consequence, the sigma(E) stress response is induced. Furthermore, due to the defects caused by inactivation of the T2S system, the Deltaeps deletion mutant of V. cholerae strain N16961 is incapable of surviving the passage through the infant mouse gastrointestinal tract. The growth defect and leaky outer membrane phenotypes are suppressed when the culture medium is supplemented with 5% glucose or sucrose, although the eps mutants remain sensitive to membrane-damaging agents. This suggests that the sugars do not restore the integrity of the outer membrane in the eps mutant strains per se but may provide osmoprotective functions.
authors: University of Michigan Medical School, Department of Microbiology and Immunology, 1150 West Medical Center Drive, 6741 Medical Science Building II, Ann Arbor, MI 48109-0620, USA.
authors: Aleksandra E
authors: AE
authors: Sikora
authors: Suzanne R
authors: SR
authors: Lybarger
authors: Maria
authors: M
authors: Sandkvist
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D002771:Cholera / Q000382:microbiology; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D051379:Mice; D009154:Mutation / Q000235:genetics*; D011112:Polymyxin B / Q000494:pharmacology; D015854:Up-Regulation; D014734:Vibrio cholerae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D011112:Polymyxin B