Prolyl tripeptidyl peptidase from Porphyromonas gingivalis - A novel enzyme with possible pathological implications for the development of periodontitis

Porphyromonas gingivalis possesses a complex proteolytic system, which is e ssential for both its growth and evasion of host defense mechanisms, In thi s report we characterized, both at a protein and genomic level, a novel pep tidase of this system with prolyl tripeptidyl peptidase activity. The enzym e was purified to homogeneity, and its enzymatic activity and biochemical p roperties were investigated The amino acid sequence at the amino terminus a nd of internal peptide fragments enabled identification of the gene encodin g this enzyme, which we refer to as PtpA for prolyl tripeptidyl peptidase A . The gene encodes an 82-kDa protein, which contains a GWSYGG motif, charac teristic for members of the S9 prolyl oligopeptidase family of serine prote ases. However, it does not share any structural similarity to Other tripept idyl peptidases, which, belong to the subtilisin family. The production of prolyl tripeptidyl peptidase may contribute to the pathogenesis of periodon tal tissue destruction through the mutual interaction of this enzyme, host and bacterial collagenases, and, dipeptidyl peptidases in the degradation o f collagen during the course of infection.