title: Interaction between two murein (peptidoglycan) synthases, PBP3 and PBP1B, in Escherichia coli.
abstract: The murein (peptidoglycan) sacculus is an essential polymer embedded in the bacterial envelope. The Escherichia coli class B penicillin-binding protein (PBP) 3 is a murein transpeptidase and essential for cell division. In an affinity chromatography experiment, the bifunctional transglycosylase-transpeptidase murein synthase PBP1B was retained by PBP3-sepharose when a membrane fraction of E. coli was applied. The direct protein-protein interaction between purified PBP3 and PBP1B was characterized in vitro by surface plasmon resonance. The interaction was confirmed in vivo employing two different methods: by a bacterial two-hybrid system, and by cross-linking/co-immunoprecipitation. In the bacterial two-hybrid system, a truncated PBP3 comprising the N-terminal 56 amino acids interacted with PBP1B. Both synthases could be cross-linked in vivo in wild-type cells and in cells lacking FtsW or FtsN. PBP1B localized diffusely and in foci at the septation site and also at the side wall. Statistical analysis of the immunofluorescence signals revealed that the localization of PBP1B at the septation site depended on the physical presence of PBP3, but not on the activity of PBP3. These studies have demonstrated, for the first time, a direct interaction between a class B PBP (PBP3) and a class A PBP (PBP1B) in vitro and in vivo, indicating that different murein synthases might act in concert to enlarge the murein sacculus during cell division.
authors.affiliation: Mikrobielle Genetik, Universität Tübingen, D-72076 Tübingen, Auf der Morgenstelle 28, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Bertsche
authors.forename: Thomas
authors.initials: T
authors.lastname: Kast
authors.forename: Benoît
authors.initials: B
authors.lastname: Wolf
authors.forename: Claudine
authors.initials: C
authors.lastname: Fraipont
authors.forename: Mirjam E G
authors.initials: ME
authors.lastname: Aarsman
authors.forename: Kai
authors.initials: K
authors.lastname: Kannenberg
authors.forename: Moritz
authors.initials: M
authors.lastname: von Rechenberg
authors.forename: Martine
authors.initials: M
authors.lastname: Nguyen-Distèche
authors.forename: Tanneke
authors.initials: T
authors.lastname: den Blaauwen
authors.forename: Joachim-Volker
authors.initials: JV
authors.lastname: Höltje
authors.forename: Waldemar
authors.initials: W
authors.lastname: Vollmer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002455:Cell Division; D002473:Cell Wall / Q000378:metabolism; D002846:Chromatography, Affinity / Q000379:methods; D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D046915:Penicillin-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D010457:Peptidoglycan / Q000378:metabolism; D025941:Protein Interaction Mapping; D020349:Surface Plasmon Resonance; D020798:Two-Hybrid System Techniques
chemical_list: D001426:Bacterial Proteins; D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D029968:Escherichia coli Proteins; C098711:FtsN protein, E coli; D008565:Membrane Proteins; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; C061684:FtsW protein, Bacteria