New Crystallographic Snapshots of Large Domain Movements in Bacterial 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase.
New Crystallographic Snapshots of Large Domain Movements in Bacterial 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase.
复制标题
细菌 3-羟基-3-甲基戊二酰辅酶 A 还原酶大域运动的新晶体学快照。
DOI：
10.1021/acs.biochem.8b00869
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发表时间：
2018
期刊：
影响因子：
2.9
通讯作者：
Kung,Yan
中科院分区：
文献类型：
--
作者：
Ragwan,EdwinR;Arai,Eri;Kung,Yan
3-羟基-3-甲基戊二酰辅酶A（HMG-CoA）还原酶（HMGR）催化甲羟戊酸途径的第一个关键步骤，该途径在生物学中用于无数代谢物的生物合成。HMGR消耗2当量的辅因子NAD（P）H以进行HMG-CoA至甲羟戊酸的四电子还原，从而产生类固醇和类异戊二烯，这是最大类别的天然产物。最近的结构数据表明，HMGR含有一个高度移动的C-末端结构域（CTD），据信该结构域采用许多不同的构象，以允许底物、辅因子和产物在反应循环期间的特定点处结合和解离。在这里，我们的特点是HMGR从Delftia acidovoransas一个NADH特异性酶和确定的晶体结构的酶在未结合，甲羟戊酸结合，和NADH和柠檬酸结合状态。总之，这些结构描绘了活性位点和辅因子结合位点中的配体结合，同时说明了保守的螺旋基序如何赋予NAD（P）H辅因子特异性。出乎意料的是，NADH结合的结构也揭示了CTD的新构象，其中结构域已经“翻转”颠倒，同时直接结合辅因子。通过捕获这些结构快照，这项工作不仅扩大了已知的HMGR结构域运动范围，而且还为这种生物学上重要的酶的催化机制提供了有价值的见解。
The enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMGR) catalyzes the first committed step of the mevalonate pathway, which is used across biology in the biosynthesis of countless metabolites. HMGR consumes 2 equiv of the cofactor NAD(P)H to perform the four-electron reduction of HMG-CoA to mevalonate toward the production of steroids and isoprenoids, the largest class of natural products. Recent structural data have shown that HMGR contains a highly mobile C-terminal domain (CTD) that is believed to adopt many different conformations to permit binding and dissociation of the substrate, cofactors, and products at specific points during the reaction cycle. Here, we have characterized the HMGR fromDelftia acidovoransas an NADH-specific enzyme and determined crystal structures of the enzyme in unbound, mevalonate-bound, and NADH- and citrate-bound states. Together, these structures depict ligand binding in both the active site and the cofactor-binding site while illustrating how a conserved helical motif confers NAD(P)H cofactor specificity. Unexpectedly, the NADH-bound structure also reveals a new conformation of the CTD, in which the domain has “flipped” upside-down, while directly binding the cofactor. By capturing these structural snapshots, this work not only expands the known range of HMGR domain movement but also provides valuable insight into the catalytic mechanism of this biologically important enzyme.