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Interaction between two murein (peptidoglycan) synthases, PBP3 and PBP1B, in Escherichia coli
Author(s) -
Bertsche Ute,
Kast Thomas,
Wolf Benoît,
Fraipont Claudine,
Aarsman Mirjam E. G.,
Kannenberg Kai,
Von Rechenberg Moritz,
NguyenDistèche Martine,
Den Blaauwen Tanneke,
Höltje JoachimVolker,
Vollmer Waldemar
Publication year - 2006
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2006.05280.x
Subject(s) - peptidoglycan , biology , penicillin binding proteins , escherichia coli , biochemistry , in vivo , bacterial cell structure , lipid ii , microbiology and biotechnology , cell wall , gene , bacteria , genetics
Summary 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.