title: Effects of multiple deletions of murein hydrolases on viability, septum cleavage, and sensitivity to large toxic molecules in Escherichia coli.
abstract: The multiplicity of murein hydrolases found in most bacteria presents an obstacle to demonstrating the necessity of these potentially autolytic enzymes. Therefore, Escherichia coli mutants with deletions in multiple murein hydrolases, including lytic transglycosylases, amidases, and DD-endopeptidases, were constructed. Even a mutant from which seven different hydrolases were deleted was viable and grew at a normal rate. However, penicillin-induced lysis was retarded. Most of the mutants were affected in septum cleavage, which resulted in the formation of chains of cells. All three enzymes were shown to be capable of splitting the septum. Failure to cleave the septum resulted in an increase in outer membrane permeability, and thus the murein hydrolase mutants did not grow on MacConkey agar plates. In addition, the hydrolase mutants not only could be lysed by lysozyme in the absence of EDTA but also were sensitive to high-molecular-weight antibiotics, such as vancomycin and bacitracin, which are normally ineffective against E. coli.
authors.affiliation: Max-Planck-Institut für Entwicklungsbiologie, Abteilung Biochemie, 72076 Tübingen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Heidrich
authors.forename: Astrid
authors.initials: A
authors.lastname: Ursinus
authors.forename: Jürgen
authors.initials: J
authors.lastname: Berger
authors.forename: Heinz
authors.initials: H
authors.lastname: Schwarz
authors.forename: Joachim-Volker
authors.initials: JV
authors.lastname: Höltje
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001414:Bacitracin / Q000494:pharmacology; D001433:Bacteriolysis; D002463:Cell Membrane Permeability; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D017353:Gene Deletion; D008826:Microbial Sensitivity Tests; D008854:Microscopy, Electron; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000235:genetics* / Q000378:metabolism; D010406:Penicillins / Q000494:pharmacology; D010457:Peptidoglycan / Q000737:chemistry; D010641:Phenotype; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins; D010457:Peptidoglycan; D001414:Bacitracin; D014640:Vancomycin; D009238:N-Acetylmuramoyl-L-alanine Amidase