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【目的】σ因子是细菌RNA聚合酶全酶的重要组分,包括必须σ因子和选择性σ因子。SigF作为重要的选择性σ因子影响结核分枝杆菌(Mycobacterium tuberculosis)的致病性和毒力等重要的功能。与之对应的在非致病性、快速生长的分枝杆菌耻垢分枝杆菌(M.smegmatis)中,sigF的调控可能与其适应一定的生理环境相关。【方法】通过基因敲除、遗传互补和抗药性分析,系统的研究了耻垢分枝杆菌SigF的应答调控。【结果】sigF敲除菌株与野生菌相比,对过氧化氢特别敏感,并且这种敏感性能够通过反式互补野生型的基因得到回复;由于细菌体内的抗氧化能力与耐药性有较高的相关性,进一步分析sigF敲除菌株的抗药性和抗氧化相关基因的表达情况,显示SigF影响细菌清除过氧化氢的能力,但是并不影响包括异烟肼等药物的敏感性及与异烟肼敏感性相关基因的表达。【结论】SigF调控的活性氧胁迫应答途径与异烟肼活化的氧化胁迫应答途径不同。另外,实验显示SigF参与了耻垢分枝杆菌的色素的合成,提示SigF参与的是光氧化胁迫应答途径,与药物引起的氧化胁迫应答途径是不同的通路。
【Objective】 σ factor is an important component of the bacterial RNA polymerase holoenzyme, including the necessary σ factor and selective σ factor. SigF plays an important role as an important sigma factor in the pathogenicity and virulence of Mycobacterium tuberculosis. Correspondingly, the regulation of sigF in M.smegmatis, a nonpathogenic, rapidly growing mycobacterium, may be related to its adaptation to a certain physiological environment. 【Method】 The gene regulation of Mycobacterium smegmatis SigF was systematically studied by gene knockout, genetic complementation and drug resistance analysis. [Results] The sigF knockout strain was particularly sensitive to hydrogen peroxide as compared to wild-type strain, and this sensitivity was restored by trans-complementation of the wild-type gene. Because of the antioxidant capacity and drug resistance in bacteria Further analysis of the resistance of sigF knockout strains and the expression of antioxidant-related genes showed that SigF affected the ability of bacteria to eliminate hydrogen peroxide but did not affect the sensitivity and specificity of drugs including isoniazid Expression of hydrazin sensitivity related genes. 【Conclusion】 SigF-regulated pathway of reactive oxygen species response is different from that of isoniazid-activated oxidative stress response. In addition, experiments have shown that SigF is involved in the pigment synthesis of M. smegmatis, suggesting that SigF is involved in the photooxidative stress response pathway, which is a different pathway from drug-induced oxidative stress response.