Agoni Clement, Ramharack Pritika, Soliman Mahmoud E S
Molecular Bio-computation and Drug Design Research Laboratory, School of Health Sciences, University of KwaZulu- Natal, Westville Campus, Durban 4001, South Africa.
Comb Chem High Throughput Screen. 2018;21(6):453-460. doi: 10.2174/1386207321666180716093617.
Rifampin resistance has dampened the existing efforts being made to control the global crisis of Tuberculosis and antimicrobial resistance in general. Previous studies that attempted to provide insights into the structural mechanism of Rifampin resistance did not utilize the X-ray crystal structure of Mycobacterium tuberculosis RNA polymerase due to its unavailability.
METHODS/RESULTS: We provide an atomistic mechanism of Rifampin resistance in a single active site mutating Mycobacterium tuberculosis RNA polymerase, using a recently resolved crystal structure. We also unravel the structural interplay of this mutation upon co-binding of Rifampin with a novel inhibitor, D-AAP1. Mutation distorted the overall conformational landscape of Mycobacterium tuberculosis RNA polymerase, reduced binding affinity of Rifampin and shifted the overall residue interaction network of the enzyme upon binding of only Rifampin. Interestingly, co-binding with DAAP1, though impacted by the mutation, exhibited improved Rifampin binding interactions amidst a distorted residue interaction network.
Findings offer vital conformational dynamics and structural mechanisms of mutant enzyme-single ligand and mutant enzyme-dual ligand interactions which could potentially shift the current therapeutic protocol of Tuberculosis infections.
利福平耐药性削弱了目前为控制全球结核病危机以及总体抗菌药物耐药性所做的努力。以往试图深入了解利福平耐药性结构机制的研究，由于无法获得结核分枝杆菌RNA聚合酶的X射线晶体结构而未能开展。
方法/结果：我们利用最近解析的晶体结构，提供了单个活性位点突变的结核分枝杆菌RNA聚合酶中利福平耐药性的原子机制。我们还揭示了该突变在利福平与新型抑制剂D - AAP1共同结合时的结构相互作用。突变扭曲了结核分枝杆菌RNA聚合酶的整体构象格局，降低了利福平的结合亲和力，并在仅结合利福平时改变了该酶的整体残基相互作用网络。有趣的是，与D - AAP1共同结合时，尽管受到突变影响，但在扭曲的残基相互作用网络中，利福平的结合相互作用有所改善。
研究结果提供了突变酶 - 单配体和突变酶 - 双配体相互作用的重要构象动力学和结构机制，这可能会改变目前结核病感染的治疗方案。
