Participation of the secreted dipeptidyl and tripeptidyl aminopeptidases in asaccharolytic growth of Porphyromonas gingivalis.
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.


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.


CONCLUSIONS
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.
Oda
H
H
Department of Periodontology, Nippon Dental University School of Life at Tokyo, Tokyo, Japan.
Saiki
K
K
Tonosaki
M
M
Yajima
A
A
Konishi
K
K
D018829:Adhesins, Bacterial / Q000378:metabolism; D000626:Aminopeptidases; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D003470:Culture Media; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000235:genetics / Q000378:metabolism*; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D055786:Gene Knockout Techniques; D000080867:Gingipain Cysteine Endopeptidases; D006427:Hemin; D007074:Immunoglobulin G; D009154:Mutation; D010455:Peptides / Q000378:metabolism; D016966:Porphyromonas gingivalis / Q000201:enzymology / Q000254:growth & development*; D011994:Recombinant Proteins / Q000378:metabolism; D012710:Serum Albumin, Bovine; D024483:Vitamin K 3
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D003470:Culture Media; D000080867:Gingipain Cysteine Endopeptidases; D007074:Immunoglobulin G; D010455:Peptides; D011994:Recombinant Proteins; D012710:Serum Albumin, Bovine; D024483:Vitamin K 3; D006427:Hemin; D010450:Endopeptidases; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D003546:Cysteine Endopeptidases