Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis.
Department of Structural Biology, St Jude Children's Research Hospital, Memphis, Tennessee.
J Infect Dis. 2019 Jul 19;220(4):677-686. doi: 10.1093/infdis/jiz169.
Mycobacterium tuberculosis lipid metabolism pathways facilitate access to carbon and energy sources during infection. M. tuberculosis gene Rv1075c was annotated as a conserved hypothetical protein. We identified that Rv1075c amino acid sequence shares similarities with other bacterial lipase/esterases and we demonstrated that it has esterase activity, with preference for short-chain fatty acids, particularly acetate, with highest activity at 45°C, pH 9. Site-direct mutagenesis revealed its activity triad as Ser80, Asp244, and His247. We further determined that rRv1075c hydrolyzed triacetin and tributyrin, and it was mainly distributed in cell wall and membrane. Its expression was induced at pH 4.5, mimicking the acidic phagosome of macrophages. Mutation of Rv1075c led to reduced bacterial growth in THP-1 cells and human peripheral blood mononuclear cell-derived macrophages, and attenuated M. tuberculosis infection in mice. Our data suggest that Rv1075c is involved in ester and fatty acid metabolism inside host cells.
结核分枝杆菌脂质代谢途径有助于在感染过程中获取碳源和能源。结核分枝杆菌基因 Rv1075c 被注释为保守的假定蛋白。我们发现 Rv1075c 氨基酸序列与其他细菌脂肪酶/酯酶具有相似性，并证明它具有酯酶活性，优先作用于短链脂肪酸，特别是乙酸盐，在 45°C、pH9 时活性最高。定点突变揭示了其活性三联体为 Ser80、Asp244 和 His247。我们进一步确定 rRv1075c 可水解三醋酸甘油酯和三丁酸甘油酯，主要分布在细胞壁和膜中。其表达在 pH4.5 时被诱导，模拟巨噬细胞中的酸性吞噬体。Rv1075c 的突变导致 THP-1 细胞和人外周血单核细胞来源的巨噬细胞中细菌生长减少，并减弱了小鼠中的结核分枝杆菌感染。我们的数据表明，Rv1075c 参与宿主细胞内的酯和脂肪酸代谢。
