[ODP3C] c. その他（分子論以外はこちらに）

[ODP-039] Porphyromonas gingivalis DPPとジペプチドトランスポーターの局在

○下山 佑¹，根本 優子²，根本 孝幸²，石河 太知¹，佐々木 大輔³，古玉 芳豊¹，木村 重信⁴，佐々木 実¹ (¹岩手医科大学微生物学講座分子微生物学分野，²長崎大学大学院医歯薬学総合研究科口腔分子生化学講座，³岩手医科大学歯科保存学講座歯周療法学分野，⁴関西女子短期大学歯科衛生学科)

Porphyromonas gingivalis is an asaccharolytic Gram-negative anaerobic bacterium that represents a keystone pathogen in chronic periodontitis. The growth of P. gingivalis strictly depends on amino acid incorporated after degradation of extracellular proteins. Gingipains and dipeptidyl-peptidase (DPP) 4, DPP5, DPP7 and DPP11 are considered essential enzymes for the production of dipeptides, entry forms passing the bacterial inner membrane. In this study, we determined the localization of the four DPPs, proton-dependent oligopeptides transporter (Pot) and oligopeptide transporter (Opt), by use of immunoelectron microscopy analysis. Our biochemical studies previously indicated that Pot and Opt function as dipeptide and tripeptide transporters, respectively. Anti-DPP antibodies were raised against each purified recombinant DPP with rabbits, and anti-Pot and -Opt antibodies were produced with rats. P. gingivalis DPPs were detected in the periplasmic space in accord with the cell fractionation study of DPP5. On the other hand, the Pot as well as Opt was located at the inner membrane. These results explain the metabolism pathway that oligopeptides produced by gingipains associating at the outer membrane are converted to dipeptides by DPPs in the periplasmic space, and then, dipeptides are readily transported through the inner membrane via dipeptide transporter Pot.