This family consists of several Porphyromonas gingivalis major fimbrial subunit protein (FimA) sequences. Fimbriae of Porphyromonas gingivalis, a periodontopathogen, play an important role in its adhesion to and invasion of host cells. The fimA genes encoding fimbrillin (FimA), a subunit protein of fimbriae, have been classified into five types, types I to V, based on nucleotide sequences. It has been found that type II FimA can bind to epithelial cells most efficiently through specific host receptors [1]. Human dental plaque is a multispecies microbial biofilm that is associated with two common oral diseases, dental caries and periodontal disease. There is an inter-species contact-dependent communication system between P. gingivalis and S. cristatus that involces the Arc-A enzyme [2].

1: Functional differences among FimA variants of Porphyromonas gingivalis and their effects on adhesion to and invasion of human epithelial cells. Nakagawa I, Amano A, Kuboniwa M, Nakamura T, Kawabata S, Hamada S; Infect Immun 2002;70:277-285. PMID:11748193

2: Identification of a signalling molecule involved in bacterial intergeneric communication. Xie H, Lin X, Wang BY, Wu J, Lamont RJ; Microbiology. 2007;153:3228-3234. PMID:17906122