Department of Cellular and Molecular Sciences, Laboratory of Bioinformatics and Molecular Biology, Faculty of Science and Philosophy, Universidad Peruana Cayetano Heredia, Lima, Peru.
Department of Paediatric Infectious Diseases, Imperial College, University of London, London, England.
Int J Mycobacteriol. 2020 Apr-Jun;9(2):121-137. doi: 10.4103/ijmy.ijmy_27_20.
Rifampicin (RIF) resistance in Mycobacterium tuberculosis is frequently caused by mutations in the rpoB gene. These mutations are associated with a fitness cost, which can be overcome by compensatory mutations in other genes, among which rpoC may be the most important. We analyzed 469 Peruvian M. tuberculosis clinical isolates to identify compensatory mutations in rpoC/rpoA associated with RIF resistance.
The M. tuberculosis isolates were collected and tested for RIF susceptibility and spoligotyping. Samples were sequenced and aligned to the reference genome to identify mutations. By analyzing the sequences and the metadata, we identified a list of rpoC mutations exclusively associated with RIF resistance and mutations in rpoB. We then evaluated the distribution of these mutations along the protein sequence and tridimensional structure.
One hundred and twenty-five strains were RIF susceptible and 346 were resistant. We identified 35 potential new compensatory mutations, some of which were distributed on the interface surface between rpoB and rpoC, arising in clusters and suggesting the presence of hotspots for compensatory mutations.
This study identifies 35 putative novel compensatory mutations in the β' subunit of M. tuberculosis RNApol. Six of these (S428T, L507V, A734V, I997V, and V1252LM) are considered most likely to have a compensatory role, as they fall in the interaction zone of the two subunits and the mutation did not lead to any change in the protein's physical-chemical properties.
结核分枝杆菌利福平（RIF）耐药性通常是由 rpoB 基因突变引起的。这些突变与适应不良有关，但可以通过其他基因的补偿性突变来克服，其中 rpoC 可能是最重要的。我们分析了 469 株秘鲁结核分枝杆菌临床分离株，以鉴定与 RIF 耐药相关的 rpoC/rpoA 中的补偿性突变。
收集并测试了结核分枝杆菌分离株对 RIF 的敏感性和 spoligotyping。对样本进行测序并与参考基因组进行比对，以鉴定突变。通过分析序列和元数据，我们确定了一组与 RIF 耐药性相关的 rpoC 突变和 rpoB 突变的列表。然后，我们评估了这些突变在蛋白质序列和三维结构上的分布情况。
125 株为 RIF 敏感株，346 株为耐药株。我们鉴定了 35 个潜在的新补偿性突变，其中一些分布在 rpoB 和 rpoC 之间的界面上，呈簇状分布，表明存在补偿性突变热点。
本研究鉴定了结核分枝杆菌 RNApolβ'亚基中的 35 个潜在新补偿性突变。其中 6 个（S428T、L507V、A734V、I997V 和 V1252LM）最有可能具有补偿作用，因为它们位于两个亚基的相互作用区域，且突变没有导致蛋白质理化性质的任何改变。
