Institute of Natural Sciences, Federal University of Pará , Belém , Pará , Brazil.
Institute of Biological Sciences, Federal University of Pará , Belém , Pará , Brazil.
J Biomol Struct Dyn. 2019 Oct;37(16):4374-4383. doi: 10.1080/07391102.2018.1549508. Epub 2019 Jan 28.
The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is mainly involved in the regulation of cholesterol biosynthesis. HMGR catalyses the reduction of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) to mevalonate at the expense of two NADPH molecules in a two-step reversible reaction. In the present study, we constructed a model of human HMGR (HMGR) to explore the conformational changes of HMGR in complex with HMG-CoA and NADPH. In addition, we analysed the complete sequence of the Flap domain using molecular dynamics (MD) simulations and principal component analysis (PCA). The simulations revealed that the Flap domain plays an important role in catalytic site activation and substrate binding. The apo form of HMGR remained in an open state, while a substrate-induced closure of the Flap domain was observed for holo HMGR. Our study also demonstrated that the phosphorylation of Ser872 induces significant conformational changes in the Flap domain that lead to a complete closure of the active site, suggesting three principal conformations for the first stage of HMGR catalysis. Our results were consistent with previous proposed models for the catalytic mechanism of HMGR. Communicated by Ramaswamy H. Sarma.
酶 3-羟基-3-甲基戊二酰辅酶 A 还原酶（HMGR）主要参与胆固醇生物合成的调节。HMGR 在两步可逆反应中催化 3-羟基-3-甲基戊二酰辅酶 A（HMG-CoA）的还原为甲羟戊酸，消耗两个 NADPH 分子。在本研究中，我们构建了人 HMGR（HMGR）的模型，以探索 HMGR 与 HMG-CoA 和 NADPH 复合物的构象变化。此外，我们使用分子动力学（MD）模拟和主成分分析（PCA）对 Flap 结构域的完整序列进行了分析。模拟表明，Flap 结构域在催化位点激活和底物结合中发挥重要作用。apo 形式的 HMGR 保持开放状态，而 holo HMGR 观察到 Flap 结构域的底物诱导关闭。我们的研究还表明，Ser872 的磷酸化诱导 Flap 结构域发生显著的构象变化，导致活性位点完全关闭，这表明 HMGR 催化作用的第一阶段有三种主要构象。我们的结果与先前提出的 HMGR 催化机制模型一致。Ramaswamy H. Sarma 通讯。
