ABSTRACT
BACKGROUND AND OBJECTIVE: Porphyromonas gingivalis secretes gingipains, endopeptidases essential for the asaccharolytic growth of this bacterium. P. gingivalis also secretes dipeptidyl aminopeptidases (DPPIV and DPP-7) and a tripeptidyl aminopeptidase (PTP-A), although their role in asaccharolytic growth is unclear. The present study was carried out to elucidate the role of these dipeptidyl/tripeptidyl aminopeptidases on the asaccharolytic growth of P. gingivalis. MATERIAL AND METHODS: Knockout mutants for the DPPIV (dpp), dpp7 and/or PTP-A genes were constructed. Brain-heart infusion medium supplemented with sterile hemin and menadione (BHIHM) was used as a complex medium, and the minimal medium used was GA, in which the sole energy source was a mixture of immunoglobulin G and bovine serum albumin. Growth of P. gingivalis was monitored by measuring the optical density of the culture. RESULTS: All knockout mutants for DPPIV, dpp7 and PTP-A grew as well as strain W83 in BHIHM. In GA, growth of single-knockout and double-knockout mutants was similar to that of W83, whereas growth of a triple-knockout mutant (83-47A) was reduced. We purified recombinant DPPIV and recombinant PTP-A from recombinant Escherichia coli overproducers, and purified DPP-7 from the triple-knockout mutant 83-4A. GA supplemented with the three purified dipeptidyl/tripeptidyl aminopeptidases supported the growth of 83-47A. CONCLUSION: DPPIV, DPP-7 and PTP-A contribute to the normal growth of P. gingivalis by cleaving substrate peptides into short-chain polypeptides that are efficient energy sources for P. gingivalis.
Subject(s)
Bacterial Proteins/metabolism , Culture Media , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/metabolism , Endopeptidases/metabolism , Porphyromonas gingivalis/growth & development , Adhesins, Bacterial/metabolism , Aminopeptidases , Animals , Bacterial Proteins/genetics , Cattle , Cysteine Endopeptidases/metabolism , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/genetics , Endopeptidases/genetics , Gene Knockout Techniques , Gingipain Cysteine Endopeptidases , Hemin , Immunoglobulin G , Mutation , Peptides/metabolism , Porphyromonas gingivalis/enzymology , Recombinant Proteins/metabolism , Serum Albumin, Bovine , Vitamin K 3ABSTRACT
IMPLICATIONS: This report describes six patients who had marked hyperkalemia 60-150 min after cessation of intravenous ritodrine, which had been administered for management of preterm labor. Abnormal electrocardiographic findings are very important clues for a prompt diagnosis of hyperkalemia.
