Crystal structure of <scp>l</scp> ‐rhamnose 1‐dehydrogenase involved in the nonphosphorylative pathway of <scp>l</scp> ‐rhamnose metabolism in bacteria

Several microorganisms can utilize l-rhamnose as a carbon and energy source through the nonphosphorylative metabolic pathway, in which 1-dehydrogenase (RhaDH) catalyzes NAD(P)+-dependent oxidization of to l-rhamnono-1,4-lactone. We herein investigated crystal structures RhaDH from Azotobacter vinelandii ligand-free, NAD+-bound, NADP+-bound, l-rhamnose- NAD+-bound forms at 1.9, 2.1, 2.4, 1.6 Å resolution, respectively. The significant interactions with 2′-phosphate group NADP+, but not 2′-hydroxyl NAD+, were consistent preference for NADP+ over NAD+. C5-OH C6-methyl groups recognized by specific residues hydrogen bonds hydrophobic contact, respectively, contribute different substrate specificities other aldose 1-dehydrogenases short-chain dehydrogenase/reductase superfamily.