Faculty of Agriculture, Ehime University, Matsuyama, Japan.
Department of Bioscience, Graduate School of Agriculture, Ehime University, Matsuyama, Japan.
FEBS Lett. 2021 Mar;595(5):637-646. doi: 10.1002/1873-3468.14046. Epub 2021 Feb 5.
Several microorganisms can utilize l-rhamnose as a carbon and energy source through the nonphosphorylative metabolic pathway, in which l-rhamnose 1-dehydrogenase (RhaDH) catalyzes the NAD(P) -dependent oxidization of l-rhamnose to l-rhamnono-1,4-lactone. We herein investigated the crystal structures of RhaDH from Azotobacter vinelandii in ligand-free, NAD -bound, NADP -bound, and l-rhamnose- and NAD -bound forms at 1.9, 2.1, 2.4, and 1.6 Å resolution, respectively. The significant interactions with the 2'-phosphate group of NADP , but not the 2'-hydroxyl group of NAD , were consistent with a preference for NADP over NAD . The C5-OH and C6-methyl groups of l-rhamnose were recognized by specific residues of RhaDH through hydrogen bonds and hydrophobic contact, respectively, which contribute to the different substrate specificities from other aldose 1-dehydrogenases in the short-chain dehydrogenase/reductase superfamily.
几种微生物可以通过非磷酸化代谢途径将 l-鼠李糖用作碳源和能源，其中 l-鼠李糖 1-脱氢酶（RhaDH）催化 NAD(P)-依赖性氧化 l-鼠李糖为 l-鼠李糖-1,4-内酯。本文研究了来自固氮菌的 RhaDH 在无配体、NAD-结合、NADP-结合、l-鼠李糖和 NAD-结合形式下的晶体结构，分辨率分别为 1.9、2.1、2.4 和 1.6Å。与 NADP 的 2'-磷酸基团的显著相互作用，但不是 NAD 的 2'-羟基，与 NADP 优先于 NAD 一致。通过氢键和疏水接触，l-鼠李糖的 C5-OH 和 C6-甲基基团分别被 RhaDH 的特定残基识别，这有助于它在短链脱氢酶/还原酶超家族中与其他醛糖 1-脱氢酶具有不同的底物特异性。
