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

Area of Science:

• Biochemistry and enzymology
• Structural biology
• Biotechnology

Background:

• Metal-dependent formate dehydrogenases (Fdh) are crucial enzymes for the reversible conversion of carbon dioxide (CO2) to formate.
• Despite their efficiency, the detailed catalytic mechanisms and intermediate structures of Fdh remain largely uncharacterized.
• Understanding these aspects is vital for harnessing Fdh in biotechnological applications, such as carbon capture and renewable energy.

Purpose of the Study:

• To elucidate the key catalytic aspects and intermediate structures of metal-dependent formate dehydrogenases.
• To provide a time-resolved structural characterization of the formate dehydrogenase from *Desulfovibrio vulgaris* Hildenborough (DvFdhAB) during formate oxidation.
• To map the dynamic changes within the enzyme's catalytic pocket during the reduction-oxidation cycle.

Main Methods:

• Time-resolved X-ray crystallography was employed to capture multiple intermediate states of the enzyme.
• Crystallographic data were collected during the formate oxidation process.
• Structural models were generated to analyze the enzyme's conformational changes and substrate interactions.

Main Results:

• Five distinct intermediate structures were modeled, providing a chronological map of enzyme reduction.
• Formate molecules were directly observed within the catalytic pocket of the Fdh for the first time.
• The redox reversibility of DvFdhAB was confirmed through structural studies of reduction and reoxidation cycles in crystalline form.

Conclusions:

• This study provides unprecedented structural insights into the catalytic mechanism of metal-dependent formate dehydrogenases.
• The visualization of formate within the active site and the mapping of intermediates advance our understanding of CO2 conversion.
• These findings lay the groundwork for the rational design and optimization of Fdh enzymes for biotechnological applications.