title: Mfa4, an Accessory Protein of Mfa1 Fimbriae, Modulates Fimbrial Biogenesis, Cell Auto-Aggregation, and Biofilm Formation in Porphyromonas gingivalis.
abstract: Porphyromonas gingivalis, a gram-negative obligate anaerobic bacterium, is considered to be a key pathogen in periodontal disease. The bacterium expresses Mfa1 fimbriae, which are composed of polymers of Mfa1. The minor accessory components Mfa3, Mfa4, and Mfa5 are incorporated into these fimbriae. In this study, we characterized Mfa4 using genetically modified strains. Deficiency in the mfa4 gene decreased, but did not eliminate, expression of Mfa1 fimbriae. However, Mfa3 and Mfa5 were not incorporated because of defects in posttranslational processing and leakage into the culture supernatant, respectively. Furthermore, the mfa4-deficient mutant had an increased tendency to auto-aggregate and form biofilms, reminiscent of a mutant completely lacking Mfa1. Notably, complementation of mfa4 restored expression of structurally intact and functional Mfa1 fimbriae. Taken together, these results indicate that the accessory proteins Mfa3, Mfa4, and Mfa5 are necessary for assembly of Mfa1 fimbriae and regulation of auto-aggregation and biofilm formation of P. gingivalis. In addition, we found that Mfa3 and Mfa4 are processed to maturity by the same RgpA/B protease that processes Mfa1 subunits prior to polymerization.
authors.affiliation: Department of Oral Microbiology, Asahi University School of Dentistry, Mizuho, Gifu, Japan; Department of Orthodontics, Asahi University School of Dentistry, Mizuho, Gifu, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Ikai
authors.affiliation: Department of Oral Microbiology, Asahi University School of Dentistry, Mizuho, Gifu, Japan; Department of Microbiology, School of Dentistry, Aichi Gakuin University, Nagoya, Aichi, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Hasegawa
authors.affiliation: Department of Oral Microbiology, Asahi University School of Dentistry, Mizuho, Gifu, Japan; Department of Orthodontics, Asahi University School of Dentistry, Mizuho, Gifu, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Izumigawa
authors.affiliation: Department of Microbiology, School of Dentistry, Aichi Gakuin University, Nagoya, Aichi, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Nagano
authors.affiliation: Department of Microbiology, School of Dentistry, Aichi Gakuin University, Nagoya, Aichi, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yoshida
authors.affiliation: Department of Orthodontics, Asahi University School of Dentistry, Mizuho, Gifu, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kitai
authors.affiliation: Department of Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, KY, United States of America.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Lamont
authors.affiliation: Department of Microbiology, School of Dentistry, Aichi Gakuin University, Nagoya, Aichi, Japan.
authors.forename: Fuminobu
authors.initials: F
authors.lastname: Yoshimura
authors.affiliation: Department of Oral Microbiology, Asahi University School of Dentistry, Mizuho, Gifu, Japan.
authors.forename: Yukitaka
authors.initials: Y
authors.lastname: Murakami
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism; D001422:Bacterial Adhesion / Q000502:physiology*; D001426:Bacterial Proteins / Q000378:metabolism*; D018441:Biofilms; D003546:Cysteine Endopeptidases / Q000378:metabolism; D036781:Fimbriae Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010861:Fimbriae, Bacterial / Q000502:physiology*; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D000080867:Gingipain Cysteine Endopeptidases; D005810:Multigene Family; D016296:Mutagenesis; D001678:Organelle Biogenesis; D016966:Porphyromonas gingivalis / Q000235:genetics / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D011499:Protein Processing, Post-Translational; D013045:Species Specificity
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D000080867:Gingipain Cysteine Endopeptidases; C545438:Mfa1 protein, Porphyromonas gingivalis; D036781:Fimbriae Proteins; D003546:Cysteine Endopeptidases