Department of Biotechnology, Panjab University, 160014, Chandigarh, India.
JH-Institute of Molecular Medicine, Jamia Hamdard, Hamdard Nagar, 110062, New Delhi, India.
Sci Rep. 2019 Sep 20;9(1):13617. doi: 10.1038/s41598-019-48940-5.
Thymidylate synthase A (ThyA) is the key enzyme involved in the folate pathway in Mycobacterium tuberculosis. Mutation of key residues of ThyA enzyme which are involved in interaction with substrate 2'-deoxyuridine-5'-monophosphate (dUMP), cofactor 5,10-methylenetetrahydrofolate (MTHF), and catalytic site have caused para-aminosalicylic acid (PAS) resistance in TB patients. Focusing on R127L, L143P, C146R, L172P, A182P, and V261G mutations, including wild-type, we performed long molecular dynamics (MD) simulations in explicit solvent to investigate the molecular principles underlying PAS resistance due to missense mutations. We found that these mutations lead to (i) extensive changes in the dUMP and MTHF binding sites, (ii) weak interaction of ThyA enzyme with dUMP and MTHF by inducing conformational changes in the structure, (iii) loss of the hydrogen bond and other atomic interactions and (iv) enhanced movement of protein atoms indicated by principal component analysis (PCA). In this study, MD simulations framework has provided considerable insight into mutation induced conformational changes in the ThyA enzyme of Mycobacterium.
胸苷酸合成酶 A（ThyA）是分枝杆菌叶酸途径中涉及的关键酶。与底物 2'-脱氧尿苷-5'-单磷酸（dUMP）、辅助因子 5,10-亚甲基四氢叶酸（MTHF）和催化位点相互作用的 ThyA 酶的关键残基发生突变，导致结核患者对对氨基水杨酸（PAS）产生耐药性。我们针对 R127L、L143P、C146R、L172P、A182P 和 V261G 突变（包括野生型）进行了长分子动力学（MD）模拟，在明确溶剂中研究了由于错义突变导致 PAS 耐药的分子原理。我们发现这些突变导致：（i）dUMP 和 MTHF 结合位点的广泛变化；（ii）结构构象变化导致 ThyA 酶与 dUMP 和 MTHF 的弱相互作用；（iii）氢键和其他原子相互作用的丧失；（iv）主成分分析（PCA）表明蛋白质原子的运动增强。在这项研究中，MD 模拟框架为分枝杆菌 ThyA 酶的突变诱导构象变化提供了重要的见解。
