title: A Transposon Screen Identifies Genetic Determinants of Vibrio cholerae Resistance to High-Molecular-Weight Antibiotics.
abstract: Gram-negative bacteria are notoriously resistant to a variety of high-molecular-weight antibiotics due to the limited permeability of their outer membrane (OM). The basis of OM barrier function and the genetic factors required for its maintenance remain incompletely understood. Here, we employed transposon insertion sequencing to identify genes required for Vibrio cholerae resistance to vancomycin and bacitracin, antibiotics that are thought to be too large to efficiently penetrate the OM. The screen yielded several genes whose protein products are predicted to participate in processes important for OM barrier functions and for biofilm formation. In addition, we identified a novel factor, designated vigA (for vancomycin inhibits growth), that has not previously been characterized or linked to outer membrane function. The vigA open reading frame (ORF) codes for an inner membrane protein, and in its absence, cells became highly sensitive to glycopeptide antibiotics (vancomycin and ramoplanin) and bacitracin but not to other large antibiotics or detergents. In contrast to wild-type (WT) cells, the vigA mutant was stained with fluorescent vancomycin. These observations suggest that VigA specifically prevents the periplasmic accumulation of certain large antibiotics without exerting a general role in the maintenance of OM integrity. We also observed marked interspecies variability in the susceptibilities of Gram-negative pathogens to glycopeptides and bacitracin. Collectively, our findings suggest that the OM barrier is not absolute but rather depends on specific OM-antibiotic interactions.
authors.affiliation: Howard Hughes Medical Institute, Brigham and Women's Hospital Division of Infectious Diseases and Harvard Medical School Department of Microbiology and Immunobiology, Boston, Massachusetts, USA tdoerr@cornell.edu mwaldor@research.bwh.harvard.edu.
authors.forename: Tobias
authors.initials: T
authors.lastname: Dörr
authors.affiliation: Howard Hughes Medical Institute, Brigham and Women's Hospital Division of Infectious Diseases and Harvard Medical School Department of Microbiology and Immunobiology, Boston, Massachusetts, USA.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Delgado
authors.affiliation: Howard Hughes Medical Institute, Brigham and Women's Hospital Division of Infectious Diseases and Harvard Medical School Department of Microbiology and Immunobiology, Boston, Massachusetts, USA.
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Umans
authors.affiliation: Howard Hughes Medical Institute, Brigham and Women's Hospital Division of Infectious Diseases and Harvard Medical School Department of Microbiology and Immunobiology, Boston, Massachusetts, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Gerding
authors.affiliation: Howard Hughes Medical Institute, Brigham and Women's Hospital Division of Infectious Diseases and Harvard Medical School Department of Microbiology and Immunobiology, Boston, Massachusetts, USA.
authors.forename: Brigid M
authors.initials: BM
authors.lastname: Davis
authors.affiliation: Howard Hughes Medical Institute, Brigham and Women's Hospital Division of Infectious Diseases and Harvard Medical School Department of Microbiology and Immunobiology, Boston, Massachusetts, USA tdoerr@cornell.edu mwaldor@research.bwh.harvard.edu.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Waldor
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001414:Bacitracin / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000494:pharmacology; D004251:DNA Transposable Elements / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006020:Glycopeptides / Q000235:genetics; D008970:Molecular Weight; D016254:Mutagenesis, Insertional / Q000235:genetics; D014640:Vancomycin / Q000494:pharmacology; D014734:Vibrio cholerae / Q000187:drug effects* / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D004251:DNA Transposable Elements; D006020:Glycopeptides; D001414:Bacitracin; D014640:Vancomycin