Identification and Characterization of Prokaryotic Dipeptidyl-peptidase 5 from Porphyromonas gingivalis
作者:Yuko Ohara-Nemoto、Shakh M.A. Rouf、Mariko Naito、Amie Yanase、Fumi Tetsuo、Toshio Ono、Takeshi Kobayakawa、Yu Shimoyama、Shigenobu Kimura、Koji Nakayama、Keitarou Saiki、Kiyoshi Konishi、Takayuki K. Nemoto
DOI:10.1074/jbc.m113.527333
日期:2014.2
Background: Dipeptidyl-peptidases (DPPs) are key factors for amino acid metabolism and bacterial growth of asaccharolytic Porphyromonas gingivalis. Results: DPP5, which is specific for Ala and hydrophobic residues, is expressed in the periplasmic space of P. gingivalis.Conclusion: DPP5 was discovered in prokaryotes for the first time. Significance: The discovery of DPP5 expands understanding of amino acid and energy metabolism in prokaryotes. Porphyromonas gingivalis, a Gram-negative asaccharolytic anaerobe, is a major causative organism of chronic periodontitis. Because the bacterium utilizes amino acids as energy and carbon sources and incorporates them mainly as dipeptides, a wide variety of dipeptide production processes mediated by dipeptidyl-peptidases (DPPs) should be beneficial for the organism. In the present study, we identified the fourth P. gingivalis enzyme, DPP5. In a dpp4-7-11-disrupted P. gingivalis ATCC 33277, a DPP7-like activity still remained. PGN_0756 possessed an activity indistinguishable from that of the mutant, and was identified as a bacterial orthologue of fungal DPP5, because of its substrate specificity and 28.5% amino acid sequence identity with an Aspergillus fumigatus entity. P. gingivalis DPP5 was composed of 684 amino acids with a molecular mass of 77,453, and existed as a dimer while migrating at 66 kDa on SDS-PAGE. It preferred Ala and hydrophobic residues, had no activity toward Pro at the P1 position, and no preference for hydrophobic P2 residues, showed an optimal pH of 6.7 in the presence of NaCl, demonstrated K-m and k(cat)/K-m values for Lys-Ala-MCA of 688 m and 11.02 m(-1) s(-1), respectively, and was localized in the periplasm. DPP5 elaborately complemented DPP7 in liberation of dipeptides with hydrophobic P1 residues. Examinations of DPP- and gingipain gene-disrupted mutants indicated that DPP4, DPP5, DPP7, and DPP11 together with Arg- and Lys-gingipains cooperatively liberate most dipeptides from nutrient oligopeptides. This is the first study to report that DPP5 is expressed not only in eukaryotes, but also widely distributed in bacteria and archaea.