Identification of a novel protein promoting the colonization and survival of Finegoldia magna, a bacterial commensal and opportunistic pathogen

Abstract

Anaerobic bacteria dominate the human normal microbiota, but strikingly little is known about these commensals. Finegoldia magna is a Gram-positive anaerobe found in the skin and at other non-sterile body surfaces, but it is also an opportunistic pathogen. This study describes a novel protein designated FAF (F. magna adhesion factor) and expressed by more than 90% of F. magna isolates. The protein is present in substantial quantities at the F. magna surface but is also released from the surface. FAF forms large protein aggregates in solution and surface-associated FAF causes bacterial clumping. In skin F. magna bacteria were localized to the epidermis, where they adhere to basement membranes. FAF was found to mediate this adhesion via interactions with BM-40, a basement membrane protein. The biological significance of FAF is further underlined by the observation that it blocks the activity of LL-37, a major human antibacterial peptide. Altogether, the data demonstrate that FAF plays an important role in colonization and survival of F. magna in the human host.

A poke into the diversity and associations within human anterior nare microbial communities

“…Despite the fact that F. magna is one of the most ubiquitous anaerobic species on the skin (Higaki and Morohashi, 2003;Gao et al, 2007), only limited information is available concerning the molecular mechanisms that promote their colonization and survival. Only recently, a F. magna adhesion factor was identified and the bacteria were shown to be localized on the epidermis adhering to basement membranes (Frick et al, 2008). Whether F. magna and S. aureus in fact interfere with attachment sites or whether other factors are responsible for the observed negative correlation remains to be elucidated.…”

Candida albicans Mucin Msb2 Is a Broad-Range Protectant against Antimicrobial Peptides

“…Thus, mammalian mucins and possibly other human glycostructures (38) may loosely bind or store AMPs, but they lack tight AMP binding activity (like C. albicans mucin Msb2*), because such activity could prevent release and accessibility of human AMPs, which would be counterproductive during microbial attack. MST technology may be used in the future to determine dissociation constants of AMPs with other body or microbial glycostructures (5)(6)(7)(38)(39)(40)(41)(42).…”

“…Both bacteria and fungi are inhibited by AMPs, but they can nevertheless survive if they contain defense mechanisms that limit AMP uptake (3) or inactivate AMPs, e.g., by proteases (4). In addition, microbes may secrete AMP binding proteins as decoys to lower effective AMP concentrations in their vicinity (5)(6)(7).…”

Constitutive and Inflammation-Dependent Antimicrobial Peptides Produced by Epithelium Are Differentially Processed and Inactivated by the Commensal Finegoldia magna and the Pathogen Streptococcus pyogenes

“…In addition, a number of recent studies reported the presence of F. magna in chronic wounds, including diabetic ulcers (9)(10)(11). F. magna resides in the lower parts of the epidermal layer, where it binds to BM-40, which is part of the basal membrane (BM), via the surface-associated protein FAF (12). It is therefore likely that F. magna encounter the constitutively expressed AMPs MK and BRAK/CXCL14 during normal, noninflamed conditions.…”

“…Most strains of F. magna express a subtilisin-like enzyme, subtilase of F. magna (SufA), which is associated with the bacterial surface (13). Both FAF and SufA are produced at substantial amounts during early logarithmic phase, and, in addition to being surface associated, they are released to the environment (12,13). Thus, it is likely that high local concentrations of these proteins can be reached in vivo.…”