Structural Analysis of Butanol Dehydrogenase YqdH from Fusobacterium nucleatum Reveals Cofactor Binding Differences

Butanol dehydrogenases (BDHs) are enzymes that convert butanol to butyraldehyde using NAD(P)H as a cofactor, playing a crucial role in microbial butanol biosynthesis within the acetone-butanol-ethanol (ABE) fermentation pathway. Butanol is a promising biofuel and an important chemical intermediate.

Structural diversity among BDHs affects their cofactor and substrate specificity. High-resolution structures of BDH proteins, including those from Fusobacterium nucleatum (FnYqdH) and Thermotoga maritima (TmBDH), have shown significant differences in cofactor-binding modes.

In the FnYqdH-NADH complex, the substrate-binding cleft is open, distancing the nicotinamide group from the catalytic site, while in TmBDH-NADP, it is closed, positioning the nicotinamide group closer to the metal-binding site. This study details the structural analysis of FnYqdH and proposes a reaction mechanism, enhancing the understanding of BDH function.