[ODP3C] c. Others

[ODP-039] Localization of DPPs and dipeptide transporter Pot in Porphyromonas gingivalis defined by IEM

○Yu Shimoyama¹, Yuko Ohara-Nemoto², Takayuki K Nemoto², Taichi Ishikawa¹, Daisuke Sasaki³, Yoshitoyo Kodama¹, Shigenobu Kimura⁴, Minoru Sasaki¹ (¹Dept. Microbiol., Div. Mol. Microbiol., Iwate Med. Univ., ²Dept. Oral Mol. Biol., Course Med. Dent. Sci., Nagasaki Univ. Grad. Sch.Biomed. Sci., ³Dept. Conservative Dent., Div. Periodontol., Iwate Med. Univ., ⁴Dept. Oral Hygiene, Kansai Women’s College)

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.