title: A novel peptidoglycan binding protein crucial for PBP1A-mediated cell wall biogenesis in Vibrio cholerae.
abstract: The bacterial cell wall, which is comprised of a mesh of polysaccharide strands crosslinked via peptide bridges (peptidoglycan, PG), is critical for maintenance of cell shape and survival. PG assembly is mediated by a variety of Penicillin Binding Proteins (PBP) whose fundamental activities have been characterized in great detail; however, there is limited knowledge of the factors that modulate their activities in different environments or growth phases. In Vibrio cholerae, the cause of cholera, PG synthesis during the transition into stationary phase is primarily mediated by the bifunctional enzyme PBP1A. Here, we screened an ordered V. cholerae transposon library for mutants that are sensitive to growth inhibition by non-canonical D-amino acids (DAA), which prevent growth and maintenance of cell shape in PBP1A-deficient V. cholerae. In addition to PBP1A and its lipoprotein activator LpoA, we found that CsiV, a small periplasmic protein with no previously described function, is essential for growth in the presence of DAA. Deletion of csiV, like deletion of lpoA or the PBP1A-encoding gene mrcA, causes cells to lose their rod shape in the presence of DAA or the beta-lactam antibiotic cefsulodin, and all three mutations are synthetically lethal with deletion of mrcB, which encodes PBP1B, V. cholerae's second key bifunctional PBP. CsiV interacts with LpoA and PG but apparently not with PBP1A, supporting the hypothesis that CsiV promotes LpoA's role as an activator of PBP1A, and thereby modulates V. cholerae PG biogenesis. Finally, the requirement for CsiV in PBP1A-mediated growth of V. cholerae can be overcome either by augmenting PG synthesis or by reducing PG degradation, thereby highlighting the importance of balancing these two processes for bacterial survival.
authors.affiliation: Division of Infectious Diseases, Brigham & Women's Hospital and Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America; Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America.
authors.forename: Tobias
authors.initials: T
authors.lastname: Dörr
authors.affiliation: Division of Infectious Diseases, Brigham & Women's Hospital and Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Hubert
authors.initials: H
authors.lastname: Lam
authors.affiliation: Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå University, Umeå, Sweden.
authors.forename: Laura
authors.initials: L
authors.lastname: Alvarez
authors.affiliation: Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå University, Umeå, Sweden.
authors.forename: Felipe
authors.initials: F
authors.lastname: Cava
authors.affiliation: Division of Infectious Diseases, Brigham & Women's Hospital and Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America; Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America.
authors.forename: Brigid M
authors.initials: BM
authors.lastname: Davis
authors.affiliation: Division of Infectious Diseases, Brigham & Women's Hospital and Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America; Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Waldor
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002441:Cefsulodin / Q000494:pharmacology; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism*; D008074:Lipoproteins; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D010457:Peptidoglycan / Q000235:genetics / Q000378:metabolism; D046928:Peptidoglycan Glycosyltransferase / Q000235:genetics*; D011485:Protein Binding; D014734:Vibrio cholerae / Q000235:genetics* / Q000378:metabolism
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008074:Lipoproteins; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D046928:Peptidoglycan Glycosyltransferase; D002441:Cefsulodin