Major fimbrial subunit protein (FimA)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. 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.