Poster session

[P3-2-30] Characterization of Mfa1 fimbriae of the periodontal pathogen, Porphyromonas gingivalis D83T3 strain

〇Miwa Naoyoshi^1,2, Nawa Hiroyuki¹, Fujimoto Miyuna³, Naiki Yoshikazu², Sakae Kotaro², Iwase Tomohiko², Nisikawa Kiyoshi², Hasegawa Yoshiaki² (1. Div Pediatr Dent, Aichi-Gakuin Univ Sch Dent, 2. Div Microbiol, Aichi-Gakuin Univ Sch Dent, 3. Hashimoto Dental Clinic)

Keywords:Porphyromonas gingivalis、fimbriae、Mfa1

[Background] Porphyromonas gingivalis, a periodontal pathogen, expresses two distinct types of fimbriae, namely FimA and Mfa1 fimbriae. The Mfa1 fimbria is composed of five proteins (Mfa1–5) encoded in the mfa gene cluster. The mfa1 gene, which encodes the major component Mfa1, is classified into mfa1^70A, mfa1^70B, and mfa1⁵³ genotypes based on gene sequence, molecular weight, and antigenicity. The Mfa1 fimbriae of P. gingivalis D83T3 belongs to mfa1^70A , but the fimbriae have a different molecular weight from other mfa1^70A strains. In this study, we aimed to clarify the characteristics of Mfa1 fimbriae in strain D83T3. [Methods] The strains JI-1, fimA-deficient strain from the type strain ATCC 33277 (mfa1^70A), and D83T3 were used. Proteins were extracted from the bacterial cells and culture supernatant, and the localization of Mfa1 was examined using western blotting. Mfa1 fimbriae were purified using ion-exchange chromatography and observed using transmission electron microscopy. The expression of Mfa2, Mfa3, Mfa4, and Mfa5 were analyzed using western blotting. [Results] The Mfa1 proteins of strains JI-1 and D83T3 were detected mainly in the bacterial cells and culture supernatant, respectively. The Mfa1 fimbriae of JI-1 strain were observed as 100 nm long fibers, whereas those of D83T3 strain were more than 1 mm long. Mfa2 and Mfa3–5 were evident in the bacterial cells and purified fimbriae of JI-1, respectively. In contrast, Mfa2 was weakly detected in the bacterial cells of D83T3, and Mfa3–5 were less than detection limit. [Discussion] These results indicate that the properties of fimbriae between strains may be different, even if they are both classified as mfa1^70A genotype.