title: In vitro murein peptidoglycan synthesis by dimers of the bifunctional transglycosylase-transpeptidase PBP1B from Escherichia coli.
abstract: PBP1B is a major bifunctional murein (peptidoglycan) synthase catalyzing transglycosylation and transpeptidation reactions in Escherichia coli. PBP1B has been shown to form dimers in vivo. The K(D) value for PBP1B dimerization was determined by surface plasmon resonance. The effect of the dimerization of PBP1B on its activities was studied with a newly developed in vitro murein synthesis assay with radioactively labeled lipid II precursor as substrate. Under conditions at which PBP1B dimerizes, the enzyme synthesized murein with long glycan strands (>25 disaccharide units) and with almost 50% of the peptides being part of cross-links. PBP1B was also capable of synthesizing trimeric muropeptide structures. Tri-, tetra-, and pentapeptide compounds could serve as acceptors in the PBP1B-catalyzed transpeptidation reaction.
authors.affiliation: Mikrobielle Genetik, Universität Tübingen, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Bertsche
authors.forename: Eefjan
authors.initials: E
authors.lastname: Breukink
authors.forename: Thomas
authors.initials: T
authors.lastname: Kast
authors.forename: Waldemar
authors.initials: W
authors.lastname: Vollmer
mesh_terms: D000595:Amino Acid Sequence; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D046915:Penicillin-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D010457:Peptidoglycan / Q000096:biosynthesis* / Q000737:chemistry; D046928:Peptidoglycan Glycosyltransferase / Q000737:chemistry* / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D046928:Peptidoglycan Glycosyltransferase; C478681:penicillin-binding protein 1B, E coli; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase