Fig. 5: Analysis of FMN binding and active site organization.

a AlbAB filament in ribbon highlighting the FMN cofactors (yellow) located at AlbA₂ (dark blue)-AlbB₂ (light blue) interfaces. b Ribbon representation showing an AlbA dimer interacting with two dimers of AlbB. The two interface FMN cofactors are shown (yellow). One AlbA α-helix containing C115 (α^FMN) – the site of covalent FMN attachment – is outlined (yellow) c FMN binding site showing covalent attachment to C115 via an 8α-S-cysteinyl linkage. The ribityl tail and isoalloxazine ring of FMN are further coordinated by multiple surrounding residues. Source data are provided as a Source Data file. d The three openings or channels to the FMN-containing active site are shown. e Surface representation colored by hydrophobicity of the FMN-containing active site. f Residues from both chains of AlbA and a single chain of AlbB contribute towards forming the FMN-binding pocket and active site located at each dimer-dimer interface.