title: Discrete and overlapping functions of peptidoglycan synthases in growth, cell division and virulence of Listeria monocytogenes.
abstract: Upon ingestion of contaminated food, Listeria monocytogenes can cause serious infections in humans that are normally treated with β-lactam antibiotics. These target Listeria's five high molecular weight penicillin-binding proteins (HMW PBPs), which are required for peptidoglycan biosynthesis. The two bi-functional class A HMW PBPs PBP A1 and PBP A2 have transglycosylase and transpeptidase domains catalyzing glycan chain polymerization and peptide cross-linking, respectively, whereas the three class B HMW PBPs B1, B2 and B3 are monofunctional transpeptidases. The precise roles of these PBPs in the cell cycle are unknown. Here we show that green fluorescent protein (GFP)-PBP fusions localized either at the septum, the lateral wall or both, suggesting distinct and overlapping functions. Genetic data confirmed this view: PBP A1 and PBP A2 could not be inactivated simultaneously, and a conditional double mutant strain is largely inducer dependent. PBP B1 is required for rod-shape and PBP B2 for cross-wall biosynthesis and viability, whereas PBP B3 is dispensable for growth and cell division. PBP B1 depletion dramatically increased β-lactam susceptibilities and stimulated spontaneous autolysis but had no effect on peptidoglycan cross-linkage. Our in vitro virulence assays indicated that the complete set of all HMW PBPs is required for maximal virulence.
authors.affiliation: FG11 Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Burgstrasse 37, 38855, Wernigerode, Germany.
authors.forename: Jeanine
authors.initials: J
authors.lastname: Rismondo
authors.forename: Lars
authors.initials: L
authors.lastname: Möller
authors.forename: Christine
authors.initials: C
authors.lastname: Aldridge
authors.forename: Joe
authors.initials: J
authors.lastname: Gray
authors.forename: Waldemar
authors.initials: W
authors.lastname: Vollmer
authors.forename: Sven
authors.initials: S
authors.lastname: Halbedel
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D008089:Listeria monocytogenes / Q000166:cytology / Q000187:drug effects / Q000472:pathogenicity* / Q000502:physiology*; D051379:Mice; D008826:Microbial Sensitivity Tests; D009154:Mutation; D046915:Penicillin-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D010457:Peptidoglycan / Q000378:metabolism; D014774:Virulence / Q000235:genetics; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D047090:beta-Lactams