Membrane-bound and secreted forms of penicillinase from Bacillus licheniformis

Abstract

Three forms of penicillinase from Bacillus licheniformis have been isolated. Two are secreted into the extracellular medium and one is membrane-bound. The secreted proteins are water-soluble; one has been previously described and sequenced, the other contains an amino-terminal extension of eight amino acid residues. The membrane-bound form behaves in all respects as a typical amphiphilic membrane protein. It binds one micelle of Triton XI00 and reassociates with egg lecithin to lipid vesicles into which the protein is incorporated. No lipids are covalently associated with the purified protein. Membrane penicillinase contains an amino-terminal peptide extension as compared to the exo forms. This tail is the most likely explanation to its amphiphilic properties.