Tracking W-Formate Dehydrogenase Structural Changes During Catalysis and Enzyme Reoxidation.

Metal-dependent formate dehydrogenases (Fdh) catalyze the reversible conversion of CO to formate, with unrivalled efficiency and selectivity. However, the key catalytic aspects of these enzymes remain unknown, preventing us from fully benefiting from their capabilities in terms of biotechnological applications. Here, we report a time-resolved characterization by X-ray crystallography of the Hildenborough SeCys/W-Fdh during formate oxidation. The results allowed us to model five different intermediate structures and to chronologically map the changes occurring during enzyme reduction. Formate molecules were assigned for the first time to populate the catalytic pocket of a Fdh. Finally, the redox reversibility of FdhAB in crystals was confirmed by reduction and reoxidation structural studies.