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Overproduction of inactive variants of the murein synthase PBP1B causes lysis in Escherichia coli

Lookup NU author(s): Professor Waldemar Vollmer


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Penicillin-binding protein 1B (PBP1B) of Escherichia coli is a bifunctional murein synthase containing both a transpeptidase domain and a transglycosylase domain. The protein is present in three forms (, ß, and ) which differ in the length of their N-terminal cytoplasmic region. Expression plasmids allowing the production of native PBP1B or of PBP1B variants with an inactive transpeptidase or transglycosylase domain or both were constructed. The inactive domains contained a single amino acid exchange in an essential active-site residue. Overproduction of the inactive PBP1B variants, but not of the active proteins, caused lysis of wild-type cells. The cells became tolerant to lysis by inactive PBP1B at a pH of 5.0, which is similar to the known tolerance for penicillin-induced lysis under acid pH conditions. Lysis was also reduced in mutant strains lacking several murein hydrolases. In particular, a strain devoid of activity of all known lytic transglycosylases was virtually tolerant, indicating that mainly the lytic transglycosylases are responsible for the observed lysis effect. A possible structural interaction between PBP1B and murein hydrolases in vivo by the formation of a multienzyme complex is discussed.

Publication metadata

Author(s): Meisel U, Höltje J-V, Vollmer W

Publication type: Article

Publication status: Published

Journal: Journal of Bacteriology

Year: 2003

Volume: 185

Issue: 18

Pages: 5342-5348

ISSN (print): 0021-9193

ISSN (electronic): 1067-8832

Publisher: American Society for Microbiology


DOI: 10.1128/JB.185.18.5342-5348.2003


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