DST-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa.
Electron Microscope Unit, University of Cape Town, Cape Town, South Africa.
PLoS One. 2018 Jul 6;13(7):e0200145. doi: 10.1371/journal.pone.0200145. eCollection 2018.
Iron-sulphur (Fe-S) clusters are ubiquitous co-factors which require multi-protein systems for their synthesis. In Mycobacterium tuberculosis, the Rv1460-Rv1461-Rv1462-Rv1463-csd-Rv1465-Rv1466 operon (suf operon) encodes the primary Fe-S cluster biogenesis system. The first gene in this operon, Rv1460, shares homology with the cyanobacterial SufR, which functions as a transcriptional repressor of the sufBCDS operon. Rv1460's function in M. tuberculosis has however not been determined. In this study, we demonstrate that M. tuberculosis mutants lacking a functional Rv1460 protein are impaired for growth under standard culture conditions. Elevated expression of Rv1460 and Rv1461 was observed in the mutant, implicating Rv1460 in the regulation of the suf operon. Binding of an Fe-S cluster to purified recombinant Rv1460 was confirmed by UV-visible spectroscopy and circular dichroism. Furthermore, three conserved cysteine residues, C203, C216 and C244, proposed to provide ligands for the coordination of an Fe-S cluster, were shown to be required for the function of Rv1460 in M. tuberculosis. Rv1460 therefore seems to be functionally analogous to cyanobacterial SufR.
铁硫 (Fe-S) 簇是普遍存在的辅因子，其合成需要多蛋白系统。在结核分枝杆菌中，Rv1460-Rv1461-Rv1462-Rv1463-csd-Rv1465-Rv1466 操纵子（suf 操纵子）编码主要的 Fe-S 簇生物发生系统。该操纵子中的第一个基因 Rv1460 与蓝细菌 SufR 具有同源性，SufR 作为 sufBCDS 操纵子的转录阻遏物发挥作用。然而，Rv1460 在结核分枝杆菌中的功能尚未确定。在这项研究中，我们证明缺乏功能性 Rv1460 蛋白的结核分枝杆菌突变体在标准培养条件下的生长受到损害。在突变体中观察到 Rv1460 和 Rv1461 的表达水平升高，表明 Rv1460 参与了 suf 操纵子的调控。通过紫外可见光谱和圆二色性证实了纯化重组 Rv1460 与 Fe-S 簇的结合。此外，三个保守的半胱氨酸残基 C203、C216 和 C244 被提议为提供配位 Fe-S 簇的配体，对于 Rv1460 在结核分枝杆菌中的功能是必需的。因此，Rv1460 似乎在功能上类似于蓝细菌 SufR。
