title: Inducible oxacillin-hydrolyzing beta-lactamase in a methylotrophic bacterium.
abstract: A novel beta-lactamase (beta-lactam-hydrolase, EC 3.5.2.6) was detected in a culture of Pseudomonas C, an obligatory methylotroph. This is the first beta-lactamase discovered in a methylotrophic organism. The inducible cell-bound enzyme with broad-spectrum activity against penicillins, was purified 77-fold from cell extracts of the methanol-grown bacterium, and its molecular weight was estimated to be 30,000. As a group, the isoxazolyl penicillins are the favored substrates, while cephalosporins are resistant to hydrolysis and act as mild competitive inhibitors. The activity of this M-OXA beta-lactamase focused as a single band at an acidic pI value (5.5) similar to that of PSE- and TEM-type enzymes, but can be clearly distinguished from other OXA-type beta-lactamases, all of which focus in the alkaline region. The enzyme is coded by a non-transferable gene. Based on the sum of its physical and biochemical properties, the M-OXA beta-lactamase is distinguishable from all previously described beta-lactamases, although immunological studies revealed some cross reactivity with the plasmid mediated OXA-2 enzyme.
authors.affiliation: Department of Molecular Biology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
authors.forename: N S
authors.initials: NS
authors.lastname: Samuelov
authors.forename: N
authors.initials: N
authors.lastname: Citri
mesh_terms: D004790:Enzyme Induction; D007700:Kinetics; D000432:Methanol / Q000378:metabolism*; D010068:Oxacillin / Q000378:metabolism; D011549:Pseudomonas / Q000201:enzymology / Q000378:metabolism*; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D001618:beta-Lactamases; D010068:Oxacillin; D000432:Methanol