Kumar Satish, Jena Lingaraja
Bioinformatics Centre and Biochemistry, Mahatma Gandhi Institute of Medical Sciences, Sevagram 442 102, India.
Genomics Inform. 2014 Dec;12(4):276-82. doi: 10.5808/GI.2014.12.4.276. Epub 2014 Dec 31.
The disease tuberculosis, caused by Mycobacterium tuberculosis (MTB), remains a major cause of morbidity and mortality in developing countries. The evolution of drug-resistant tuberculosis causes a foremost threat to global health. Most drug-resistant MTB clinical strains are showing resistance to isoniazid and rifampicin (RIF), the frontline anti-tuberculosis drugs. Mutation in rpoB, the beta subunit of DNA-directed RNA polymerase of MTB, is reported to be a major cause of RIF resistance. Amongst mutations in the well-defined 81-base-pair central region of the rpoB gene, mutation at codon 450 (S450L) and 445 (H445Y) is mainly associated with RIF resistance. In this study, we modeled two resistant mutants of rpoB (S450L and H445Y) using Modeller9v10 and performed a docking analysis with RIF using AutoDock4.2 and compared the docking results of these mutants with the wild-type rpoB. The docking results revealed that RIF more effectively inhibited the wild-type rpoB with low binding energy than rpoB mutants. The rpoB mutants interacted with RIF with positive binding energy, revealing the incapableness of RIF inhibition and thus showing resistance. Subsequently, this was verified by molecular dynamics simulations. This in silico evidence may help us understand RIF resistance in rpoB mutant strains.
由结核分枝杆菌（MTB）引起的结核病，在发展中国家仍然是发病和死亡的主要原因。耐多药结核病的演变对全球健康构成了首要威胁。大多数耐多药MTB临床菌株对一线抗结核药物异烟肼和利福平（RIF）表现出耐药性。据报道，MTB的DNA指导的RNA聚合酶的β亚基rpoB中的突变是RIF耐药的主要原因。在rpoB基因明确的81个碱基对的中央区域的突变中，密码子450（S450L）和445（H445Y）处的突变主要与RIF耐药性相关。在本研究中，我们使用Modeller9v10对rpoB的两个耐药突变体（S450L和H445Y）进行建模，并使用AutoDock4.2对RIF进行对接分析，并将这些突变体与野生型rpoB的对接结果进行比较。对接结果表明，与rpoB突变体相比，RIF以低结合能更有效地抑制野生型rpoB。rpoB突变体与RIF以正结合能相互作用，表明RIF无法抑制，从而显示出耐药性。随后，通过分子动力学模拟对其进行了验证。这一计算机模拟证据可能有助于我们理解rpoB突变菌株中的RIF耐药性。
