Structural and mechanistic basis of sulfolytic C–S bond cleavage by an Fe(ii)/α-ketoglutarate-dependent sulfoquinovose dioxygenase

Abstract

Sulfoquinovose dioxygenase (SqoD) enables bacterial carbon assimilation from the abundant sulfosugar sulfoquinovose (SQ) by Fe(ii)/α-ketoglutarate (αKG)-dependent C–S bond cleavage. Here we report crystal structures of the Marinobacterium aestuarii enzyme (MaSqoD) in multiple states with inert Mn2+ in place of Fe2+ (SQ-bound; Mn2+·αKG; Mn2+·αKG·SQ; Mn2+·succinate), together with steady-state and pre-steady-state kinetics that link the structures with kinetically-inferred intermediates. The X-ray crystal structures show a canonical 2-His-1-carboxylate core metal center with SQ recognition via a mainly neutral network (Gln120, Trp253, backbone carbonyl of Ala185, and backbone amides of Ala89/M..