Penicillinase-releasing protease of Bacillus licheniformis 749 Specificity for hydroxyamino acids.

The membrane penicillinase of Bacillus licheniformis 749/C differs from the exopenicillinase in that it has an additional 24 amino acid residues and a phosphatidylserine at the NH2 terminus (Yamamoto, S., and Lampen, J.O. (1976) J. Biol. Chem. 251, 4095-4101). The conversion of the membrane penicillinase to the exo form is probably carried out by a specific penicillinase-releasing protease (PR-protease) whose properties are generally consistent with the properties of penicillinase secretion. The substrate specificity of the PR-protease was determined by identifying the NH2 and COOH termini of the peptides produced by hydrolysis of ribonuclease B and beef insulin. The enzyme hydrolyzed only peptide bonds involving the carboxyl groups of serine or thrombine. Similar bonds in synthetic di- or tripeptides of L-serine were not cleaved. The existence of seryl-lysine and threonyl-glucamic acid bonds in the protease-susceptible (phospholipopeptide) region of the membrane penicillinase and the presence of only lysine or glutamic acid at the NH2 terminus of the exoenzyme released in vivo are consistent with the specificity of PR-protease; hence, we propose that this enzyme has an essential role in the formation of exopenicillinase. The PR-protease is a potential tool for protein sequence determination because of its narrow and novel substrate specificity.