Singh Kumar Sachin, Sharma Rishabh, Keshari Deepa, Singh Nirbhay, Singh Sudheer Kumar
Microbiology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India.
Microbiology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India.
Tuberculosis (Edinb). 2017 Sep;106:73-81. doi: 10.1016/j.tube.2017.07.006. Epub 2017 Jul 18.
Malate synthase is a condensing enzyme responsible for conversion of glyoxylate to malate in the presence of acetyl-CoA. This reaction helps in bypassing the TCA cycle reactions involving carbon loss and leads to diverting some of the carbon skeletons to gluconeogenic events while rest can continue to provide TCA cycle intermediates. Malate synthase (GlcB) is encoded by MRA_1848 of Mycobacterium tuberculosis H37Ra (Mtb-Ra). We developed a knockdown (KD) Mtb-Ra strain by down-regulating GlcB. The survival studies suggested increased susceptibility to oxidative and nitrosative stress as well as to rifampicin. The susceptibility profile was reversed in the presence of free radical scavengers. Also, KD showed reduced biofilm maturation, failed to enter persistent state, and showed reduced growth inside macrophages. The study of post-endocytosis events showed differences in late stage endosomal maturation behavior in macrophages infected with KD compared to WT. Increased iNOS, LAMP1 and cathepsin D expression was observed in macrophages infected with KD compared to WT.
苹果酸合酶是一种缩合酶，负责在乙酰辅酶A存在的情况下将乙醛酸转化为苹果酸。该反应有助于绕过涉及碳损失的三羧酸循环反应，并导致将一些碳骨架转移到糖异生过程中，而其余部分则可继续提供三羧酸循环中间体。苹果酸合酶（GlcB）由结核分枝杆菌H37Ra（Mtb-Ra）的MRA_1848编码。我们通过下调GlcB开发了一种基因敲低（KD）的Mtb-Ra菌株。生存研究表明，该菌株对氧化应激、亚硝化应激以及利福平的敏感性增加。在存在自由基清除剂的情况下，这种敏感性特征发生了逆转。此外，基因敲低显示生物膜成熟减少，无法进入持续状态，并且在巨噬细胞内的生长也减少。对胞吞后事件的研究表明，与野生型相比，感染基因敲低菌株的巨噬细胞在晚期内体成熟行为上存在差异。与野生型相比，在感染基因敲低菌株的巨噬细胞中观察到诱导型一氧化氮合酶、溶酶体相关膜蛋白1和组织蛋白酶D的表达增加。
