title: Cell separation in Vibrio cholerae is mediated by a single amidase whose action is modulated by two nonredundant activators.
abstract: Synthesis and hydrolysis of septal peptidoglycan (PG) are critical processes at the conclusion of cell division that enable separation of daughter cells. Cleavage of septal PG is mediated by PG amidases, hydrolytic enzymes that release peptide side chains from the glycan strand. Most gammaproteobacteria, including Escherichia coli, encode several functionally redundant periplasmic amidases. However, members of the Vibrio genus, including the enteric pathogen Vibrio cholerae, encode only a single PG amidase, AmiB. Here, we show that V. cholerae AmiB is crucial for cell division and growth. Genetic and biochemical analyses indicated that AmiB is regulated by two activators, EnvC and NlpD, at least one of which is required for AmiB's localization to the cell division site. Localization of the activators (and thus of AmiB) is dependent upon the cell division protein FtsN. These factors mediate septal PG cleavage in E. coli as well; however, their precise roles vary between the two organisms in a number of ways. Notably, even though V. cholerae EnvC and NlpD appear to be functionally redundant under most growth conditions tested, NlpD is specifically required for intestinal colonization in the infant mouse model of cholera and for V. cholerae resistance against bile salts, perhaps due to environmental regulation of AmiB or its activators. Collectively, our findings reveal that although the cellular components that enable cleavage of septal PG appear to be generally conserved between E. coli and V. cholerae, they can be combined into diverse functional regulatory networks.
authors.affiliation: Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA Department of Microbiology and Immunobiology, Harvard Medical School and HHMI, Boston, Massachusetts, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Möll
authors.affiliation: Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA Department of Microbiology and Immunobiology, Harvard Medical School and HHMI, Boston, Massachusetts, USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Dörr
authors.affiliation: Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Center for Microbial Research, Umeå University, Umeå, Sweden.
authors.forename: Laura
authors.initials: L
authors.lastname: Alvarez
authors.affiliation: Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA Department of Microbiology and Immunobiology, Harvard Medical School and HHMI, Boston, Massachusetts, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Chao
authors.affiliation: Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA Department of Microbiology and Immunobiology, Harvard Medical School and HHMI, Boston, Massachusetts, USA.
authors.forename: Brigid M
authors.initials: BM
authors.lastname: Davis
authors.affiliation: Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Center for Microbial Research, Umeå University, Umeå, Sweden.
authors.forename: Felipe
authors.initials: F
authors.lastname: Cava
authors.affiliation: Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA Department of Microbiology and Immunobiology, Harvard Medical School and HHMI, Boston, Massachusetts, USA mwaldor@research.bwh.harvard.edu.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Waldor
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000833:Animals, Suckling; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D051379:Mice; D021381:Protein Transport; D014734:Vibrio cholerae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D000581:Amidohydrolases; C019665:amidase