【摘要】 【目的】活性氧类分子是机体有氧代谢的自然产物,可以引起氧化损伤,导致细胞DNA突变、蛋白质失活,是细菌耐药产生的原因之一。蚯蚓血红蛋白家族是能携带氧、可逆地结合氧的一类蛋白,在氧代谢过程中发挥重要作用,与活性氧类分子介导的细菌耐药相关。预测耻垢分枝杆菌（Mycobacterium smegmatis）MSMEG₃312是蚯蚓血红蛋白样蛋白,其功能可能与细菌抗药性有关。【方法】通过生物信息学预测耻垢分枝杆菌MSMEG₃312的结构特征。通过基因敲除、遗传互补和抗药性分析以及启动子表达测定等方法研究MSMEG₃312与耻垢分枝杆菌抗药的相关性。【结果】与野生菌株mc2155相比,msmeg₃312敲除菌株表现为抗大环内酯类抗生素,而且回补msmeg₃312部分丧失了这种耐药表型。此外,大环内酯类抗生素的胁迫在统计上显著下调msmeg₃312启动子的表达。另外,对作用于核糖体的其他药物,敲除菌株和野生菌株没有抗药性差异。【结论】生物信息学分析显示MSMEG₃312的氨基酸序列具有典型的蚯蚓血红蛋白保守的HHE结构域,预测其二级结构含有4个α-螺旋组成的典型蚯蚓血红蛋白结构。MSMEG₃312与耻垢分枝杆菌对大环内酯类抗生素的药物敏感性相关,其可能通过影响药物与核糖体50S亚基的作用来发挥功能。更多还原

【Abstract】 [Objective]Reactive oxygen species are natural products of metabolism in aerobic organisms,which lead to oxidative damage,such as DNA mutation,protein inactivation and drug resistance. MSMEG₃312 was predicted as a hemerythrin-like protein,which can carry oxygen and reversibly bind to oxygen,thus it might play important roles in the process of oxygen metabolism. In this study,we explored the role of MSMEG₃312 in drug resistance. [Methods] On the basis of bioinformatics,we identified the conserved sequence of HHE domain in MSMEG₃312 and it was predicted to have typical α-helix at secondary structure. To explore potential functions of MSMEG₃312,we constructed the msmeg₃312 knockout strain and compare the susceptibility to various drugs to its parent strain,mc2155. In addition,we also measured the promoter response when treatment of erythromycin. [Results]Genetic results showed that MSMEG₃312 is not necessary for M. smegmatis growth at 7H9 rich medium. The msmeg 3312 knockout strain showed increased erythromycin resistance. Moreover,the drug resistance is only limited to erythromycin which its mechanism of action is by binding to the 50 S subunit of the bacteria ribosomal complex and then inhibit protein synthesis. However,there were no different MICs of other antibiotics,targets for protein synthesis inhibition,but not 50 S subunit,such as tetracyclines,aminoglycosides and chloramphenicol. Moreover,we also showed that the promoter of msmeg 3312 responses to erythromycin. [Conclusions]Hemerythin-like protein MSMEG₃312 is involved in erythromycin resistance.更多还原