In silico analysis of Ffp1, an ancestral Porphyromonas spp. fimbrillin, shows differences with Fim and Mfa.

Scant information is available regarding fimbrillins within the genus , with the notable exception of those belonging to , which have been extensively researched for several years. Besides and , a third adhesin called filament-forming protein 1 (Ffp1) has recently been described and seems to be pivotal for outer membrane vesicle (OMV) production. We aimed to investigate the distribution and diversity of type V fimbrillin, particularly Ffp1, in the genus . A bioinformatics phylogenomic analysis was conducted using all accessible genomes to generate a domain search for fimbriae, using hidden Markov model profiles. Ffp1 was identified as the sole fimbrillin present in all analysed genomes. After manual verification (i.e. biocuration) of both structural and functional annotations and 3D modelling, this protein was determined to be a type V fimbrillin, with a closer structural resemblance to a fimbrillin than to FimA or Mfa1 from . It appears that Ffp1 is an ancestral fimbria, transmitted through vertical inheritance and present across all species. Additional investigations are necessary to elucidate the biogenesis of Ffp1 fimbriae and their potential role in OMV production and niche adaptation.