Treponema denticola, a human pathogen that contributes to periodontitis, survives by binding factor H (FH) to its surface through its Factor H binding protein B (FhbB). The structure of this protein is highly ordered consisting of an alpha-beta fold. This highly thermostable protein forms a weak dimer with an interface occurring along one alpha helix from each subunit in an anti-parallel alignment with no direct hydrogen bonding between the subunits [1].

1: Structure of factor H-binding protein B (FhbB) of the periopathogen, Treponema denticola: insights into progression of periodontal disease. Miller DP, Bell JK, McDowell JV, Conrad DH, Burgner JW, Heroux A, Marconi RT; J Biol Chem. 2012;287:12715-12722. PMID:22371503