CHARACTERIZATION OF PEPB, A GROUP-B STREPTOCOCCAL OLIGOPEPTIDASE

Group B streptococci were recently reported to possess a cell-associat ed collagenase. Although the enzyme hydrolyzed the synthetic collagen- like substrate N-(3-[2-furyl] acryloyl)-Leu-Gly-Pro-Ala, we found that neither the highly purified enzyme nor crude group B streptococcal ce ll lysate solubilized a film of reconstituted rat tail collagen, an ac tivity regarded as obligatory for a true collagenase. We cloned and se quenced the gene for the enzyme (pepB). The deduced amino acid sequenc e showed 66.4% identity to the PepF oligopeptidase from Lactococcus la ctis, a member of the M3 or thimet family of zinc metallopeptidases. T he group B streptococcal enzyme also showed oligopeptidase activity an d degraded a variety of small bioactive peptides, including bradykinin , neurotensin, and peptide fragments of substance P and adrenocorticot ropin.