Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India 500046.
CSIR-Indian Institute of Chemical Technology (IICT), Uppal Road, Hyderabad, India 500007.
Mitochondrion. 2024 Sep;78:101931. doi: 10.1016/j.mito.2024.101931. Epub 2024 Jul 8.
Mycobacterium tuberculosis (Mtb) successfully thrives in the host by adjusting its metabolism and manipulating the host environment. In this study, we investigated the role of Rv0547c, a protein that carries mitochondria-targeting sequence (MTS), in mycobacterial persistence. We show that Rv0547c is a functional oxidoreductase that targets host-cell mitochondria. Interestingly, the localization of Rv0547c to mitochondria was independent of the predicted MTS but depended on specific arginine residues at the N- and C-terminals. As compared to the mitochondria-localization defective mutant, Rv0547c-2SDM, wild-type Rv0547c increased mitochondrial membrane fluidity and spare respiratory capacity. To comprehend the possible reason, comparative lipidomics was performed that revealed a reduced variability of long-chain and very long-chain fatty acids as well as altered levels of phosphatidylcholine and phosphatidylinositol class of lipids upon expression of Rv0547c, explaining the increased membrane fluidity. Additionally, the over representation of propionate metabolism and β-oxidation intermediates in Rv0547c-targeted mitochondrial fractions indicated altered fatty acid metabolism, which corroborated with changes in oxygen consumption rate (OCR) upon etomoxir treatment in HEK293T cells transiently expressing Rv0547c, resulting in enhanced mitochondrial fatty acid oxidation capacity. Furthermore, Mycobacterium smegmatis over expressing Rv0547c showed increased persistence during infection of THP-1 macrophages, which correlated with its increased expression in Mtb during oxidative and nutrient starvation stresses. This study identified for the first time an Mtb protein that alters mitochondrial metabolism and aids in survival in host macrophages by altering fatty acid metabolism to its benefit and, at the same time increases mitochondrial spare respiratory capacity to mitigate infection stresses and maintain cell viability.
结核分枝杆菌（Mtb）通过调整其代谢并操纵宿主环境，成功地在宿主体内生存。在这项研究中，我们研究了携带线粒体靶向序列（MTS）的蛋白 Rv0547c 在分枝杆菌持续存在中的作用。我们表明，Rv0547c 是一种靶向宿主细胞线粒体的功能性氧化还原酶。有趣的是，Rv0547c 定位于线粒体与预测的 MTS 无关，但取决于 N-和 C-末端的特定精氨酸残基。与线粒体定位缺陷突变体 Rv0547c-2SDM 相比，野生型 Rv0547c 增加了线粒体膜的流动性和备用呼吸能力。为了理解可能的原因，进行了比较脂质组学分析，结果表明，当表达 Rv0547c 时，长链和超长链脂肪酸的变异性降低，磷脂酰胆碱和磷脂酰肌醇类脂质的水平发生改变，解释了膜流动性的增加。此外，在 Rv0547c 靶向的线粒体部分中，丙酸盐代谢和β-氧化中间产物的过度表达表明脂肪酸代谢发生改变，这与在瞬时表达 Rv0547c 的 HEK293T 细胞中用 etomoxir 处理时耗氧量（OCR）的变化一致，导致线粒体脂肪酸氧化能力增强。此外，过表达 Rv0547c 的耻垢分枝杆菌在感染 THP-1 巨噬细胞时表现出更高的持续性，这与其在氧化和营养饥饿应激期间在 Mtb 中的表达增加相关。这项研究首次鉴定出一种 Mtb 蛋白，该蛋白通过改变脂肪酸代谢为其自身的利益来帮助在宿主巨噬细胞中生存，并同时增加线粒体备用呼吸能力，以减轻感染应激并维持细胞活力。
