Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) has emerged in recent decades as one of the leading causes of mortality worldwide. The burden of TB is alarmingly high, with one third affected global population as reported by WHO. Short-course treatment with an antibiotic is a powerful weapon to treat infection of susceptible MTB strain, however; MTB has developed resistance to anti-TB drugs, which is an escalating global health crisis. Thus there is urgent need to identify new drug targets. RecA is a 38 kilodalton protein required for the repair and maintenance of DNA and regulation of the SOS response. The objective of this study is to understand the effect of disruption of RecA gene (deletion mutant ΔdisA from previous study) in a surrogate model for MTB, Mycobacterium smegmatis. This study demonstrated that disruption of RecA causes enhanced susceptibility towards rifampicin and generation of ROS leading to lipid peroxidation and impaired membrane homeostasis as depicted by altered cell membrane permeability and efflux pump activity. Mass spectrometry based lipidomic analysis revealed decreased mycolic acid moieties, phosphatidylinositol mannosides (PIM), Phthiocerol dimycocerosate (DIM). Furthermore, biofilm formation was considerably reduced. Additionally, we have validated all the disrupted phenotypes by RT-PCR which showed a good correlation with the biochemical assays. Lastly, RecA mutant displayed reduced infectivity in Caenorhabditis elegans illustrating its vulnerability as antimycobacterial target. Together, present study establishes a link between DNA repair, drug efflux and biofilm formation and validates RecA as an effective drug target. Intricate studies are needed to further understand and exploit this therapeutic opportunity.

中文翻译：

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Rec A破坏揭示了耻垢分枝杆菌中DNA修复与膜损伤，外排泵活性，生物膜形成之间的相互影响。

由结核分枝杆菌（MTB）引起的结核病（TB）在近几十年来已成为全球范围内导致死亡的主要原因之一。结核病的负担令人震惊，世界卫生组织报告说，三分之一的受影响人口受全球影响。但是，用抗生素进行短程治疗是治疗易感性MTB菌株感染的有力武器。山地车对抗结核药产生了抗药性，这是一种日益严重的全球健康危机。因此，迫切需要确定新的药物靶标。RecA是一种38千道尔顿蛋白，是DNA的修复和维持以及SOS应答调节所必需的。这项研究的目的是了解在MTB耻垢分枝杆菌的替代模型中RecA基因（先前研究的缺失突变体ΔdisA）破坏的影响。这项研究表明，RecA的破坏会导致对利福平的敏感性增加，并导致ROS的产生，从而导致脂质过氧化和膜稳态的降低，如改变的细胞膜通透性和外排泵活性所描述。基于质谱的脂质组学分析显示，霉菌酸部分，磷脂酰肌醇甘露糖苷（PIM），二硫代cercercerol diycocerosate（DIM）含量降低。此外，生物膜的形成大大减少。此外，我们已经通过RT-PCR验证了所有破坏的表型，这些表型与生化分析具有良好的相关性。最后，RecA突变体在秀丽隐杆线虫中显示出降低的传染性，说明其作为抗分枝杆菌靶标的脆弱性。目前的研究共同建立了DNA修复，药物外排和生物膜形成，并确认RecA是有效的药物靶标。需要进一步的研究来进一步了解和利用这种治疗机会。