title: Cellular distribution of beta-lactamase RP4 is mediated by an outer membrane protease.
abstract: RP4 beta-lactamase extracted from the outer membrane of wild-type Escherichia coli can be resolved into several interconvertible forms that differ in their stabilities, substrate profiles and apparent molecular weights. beta-Lactamase isolated from outer membrane of strains which are lacking a protease that is involved in the cleavage of colicins differs from the beta-lactamase of parental cells in substrate profile, apparent molecular weight and the ability to interconvert. The cellular distribution of beta-lactamase also differs between wild-type and protease-deficient mutants. Both strains have equivalent amounts of beta-lactamase in their outer membranes, however the parental strain also has considerable beta-lactamase in the cytoplasmic membrane while the mutant does not. In addition the mutant contains only 30% of the parental level of enzyme in the periplasm. It is proposed that the reduced level of periplasmic enzyme is the result of a defect in processing of membrane-associated beta-lactamase. This conclusion is supported by the observation that the beta-lactamase isolated from the mutant can be converted to forms resembling those found in the parent by incubation with extracts or outer membrane isolated from the parent.
mesh_terms: D002462:Cell Membrane / Q000201:enzymology; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D009154:Mutation; D010405:Penicillinase / Q000302:isolation & purification / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D013045:Species Specificity; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D010447:Peptide Hydrolases; D010405:Penicillinase; D001618:beta-Lactamases