核糖体bS22、bL37基因的敲除增强分枝杆菌对抗生素的敏感性

Knockout of ribosomal genes bS22 and bL37 increases the sensitivity of mycobacteria to antibiotics

近年来,利用冷冻电子显微镜在分枝杆菌(mycobacteria)的核糖体中新发现了两个蛋白:位于30S亚基解码中心附近的bS22和位于50S亚基肽酰转移酶中心附近的bL37。由于这两个蛋白均邻近抗生素与核糖体结合区,推测它们可能会影响相关药物与靶点的结合。因此我们利用同源重组的方法,在野生型耻垢分枝杆菌(Mycolicibacterium smegmatis)mc2155中分别敲除这两个蛋白的编码基因,并测定菌株的生长曲线和对相关抗生素的敏感性。结果表明,与野生型相比,2株敲除株的生长速率均没有显著变化,但菌株ΔbS22相比于野生型对卷曲霉素、卡那霉素、阿米卡星、链霉素、庆大霉素、巴龙霉素和潮霉素B的敏感性增加,菌株ΔbL37相比于野生型对利奈唑胺的敏感性增加,并且这种敏感性的变化通过基因回补均得到恢复。研究结果暗示了核糖体蛋白bS22、bL37作为药物设计靶点的可能性。

In recent years,two novel proteins in the ribosomes of mycobacteria have been discovered by cryo-electron microscopy.The protein bS22 is located near the decoding center of the 30 S subunit,and the protein bL37 is located near the peptidyl transferase center of the 50 S subunit.Since these two proteins bind to conserved regions of the ribosome targeted by antibiotics,it is speculated that they might affect the binding of related drugs to these targets.Therefore,we knocked out the genes encoding these two proteins in wild-type Mycolicibacterium smegmatis mc2155 through homologous recombination,and then determined the growth curves of these mutants and their sensitivity to related antibiotics.The results showed that compared with the wild-type strain,the growth rate of these two mutants did not change significantly.However,mutantΔbS22 showed increased sensitivity to capreomycin,kanamycin,amikacin,streptomycin,gentamicin,paromomycin,and hygromycin B,while mutantΔbL37 showed increased sensitivity to linezolid.These changes in antibiotics sensitivity were restored by gene complementation.This study hints at the possibility of using ribosomal proteins bS22 and bL37 as targets for drug design.