title: Effects of inner-membrane-associated beta-lactamase on penicillin-binding protein assays. Study of stably derepressed Pseudomonas aeruginosa strains from experimental endocarditis.
abstract: We studied penicillin-binding protein (PBP) profiles of two Pseudomonas aeruginosa strains stably derepressed for constitutive, type Id beta-lactamase overproduction. Substantial levels of beta-lactamase were found to be strongly associated with isolated inner membranes of these two strains, as well as from a plasmid-encoded, TEM-2 beta-lactamase-producing control strain of P. aeruginosa. The inner membrane-associated beta-lactamase resulted in significant decreases in the intensity on autoradiographs of PBPs labelled with 35S-penicillin, yielding spurious PBP profiles for these strains. Inner membrane beta-lactamases could be substantially removed by a sonication-ultracentrifugation step, producing the bona fide PBP profiles.
authors.affiliation: Department of Microbiology, University of British Columbia, Vancouver, Canada.
authors.forename: T R
authors.initials: TR
authors.lastname: Parr
authors.forename: L
authors.initials: L
authors.lastname: Chan
authors.forename: A S
authors.initials: AS
authors.lastname: Bayer
mesh_terms: D000818:Animals; D001345:Autoradiography; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000378:metabolism*; D002442:Ceftazidime / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004591:Electrophoresis, Polyacrylamide Gel; D004697:Endocarditis, Bacterial / Q000382:microbiology*; D006602:Hexosyltransferases; D007425:Intracellular Membranes / Q000201:enzymology*; D002267:Muramoylpentapeptide Carboxypeptidase / Q000378:metabolism*; D046915:Penicillin-Binding Proteins; D010405:Penicillinase / Q000378:metabolism*; D010458:Peptidyl Transferases; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000378:metabolism; D011817:Rabbits
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D002442:Ceftazidime; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D010405:Penicillinase