Fig. 4: High-resolution structures of reaction ligands in the active site of Archaeoglobus fulgidus γ-glutamyl ligase CofE.
a An overlay of F420-1 (yellow) and F420-2 (cyan) molecules highlighting the bulge in the tail of F420-2. GTP/GDP (pink stick model), manganese and sodium cations (white spheres) are located adjacent to the terminal glutamyl binding site. b The F420-1 phospholactyl moiety binds in a secondary glutamate binding pocket and its carbonyl closely approaches the γ-phosphate atom of a modelled GTP. c Free L-glutamate binding in the primary glutamate pocket. Extensive hydrogen bonding between the co-substrate and two oxyanion-like holes via α- and γ-carboxylates locks the ligand in place. d The first, basal glutamyl of F420-2 occupies the secondary glutamate pocket and projects the carbonyl oxygen of the following cis-amide bond toward the GTP γ-phosphate atom. Polar interactions are shown as dashed white lines with distances labelled in Å units.
