BACKGROUND The intracellular concentration of heavy-metal cations, such as copper, nickel, and zinc is pivotal for the mycobacterial response to the hostile environment inside macrophages. To date, copper transport mediated by P-type ATPases across the mycobacterial plasma membrane has not been sufficiently explored. RESULTS In this work, the ATPase activity of the putative Mycobacterium tuberculosis P1B-type ATPase CtpB was associated with copper (I) transport from mycobacterial cells. Although CtpB heterologously expressed in M. smegmatis induced tolerance to toxic concentrations of Cu2+ and a metal preference for Cu+, the disruption of ctpB in M. tuberculosis cells did not promote impaired cell growth or heavy-metal accumulation in whole mutant cells in cultures under high doses of copper. In addition, the Cu+ ATPase activity of CtpB embedded in the plasma membrane showed features of high affinity/slow turnover ATPases, with enzymatic parameters KM 0.19 ± 0.04 µM and Vmax 2.29 ± 0.10 nmol/mg min. In contrast, the ctpB gene transcription was activated in cells under culture conditions that mimicked the hostile intraphagosomal environment, such as hypoxia, nitrosative and oxidative stress, but not under high doses of copper. CONCLUSIONS The overall results suggest that M. tuberculosis CtpB is associated with Cu+ transport from mycobacterial cells possibly playing a role different from copper detoxification.

中文翻译：

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CtpB 是结核分枝杆菌的质膜铜 (I) 转运 P 型 ATP 酶。


背景技术重金属阳离子（例如铜、镍和锌）的细胞内浓度对于分枝杆菌对巨噬细胞内恶劣环境的反应至关重要。迄今为止，P 型 ATP 酶介导的跨分枝杆菌质膜的铜转运尚未得到充分探索。结果在这项工作中，假定的结核分枝杆菌 P1B 型 ATP 酶 CtpB 的 ATP 酶活性与分枝杆菌细胞的铜 (I) 转运相关。尽管在耻垢分枝杆菌中异源表达的 CtpB 诱导了对 Cu2+ 毒性浓度的耐受性和对 Cu+ 的金属偏好，但结核分枝杆菌细胞中 ctpB 的破坏并没有促进细胞生长受损或在高浓度培养物中整个突变细胞中重金属的积累。铜的剂量。此外，嵌入质膜中的 CtpB 的 Cu+ ATP 酶活性显示出高亲和力/慢周转 ATP 酶的特征，酶参数 KM 0.19 ± 0.04 µM 和 Vmax 2.29 ± 0.10 nmol/mg min。相比之下，在模拟不利的吞噬体内环境（例如缺氧、亚硝化和氧化应激）的培养条件下，ctpB 基因转录在细胞中被激活，但在高剂量的铜下则不然。结论 总体结果表明，结核分枝杆菌 CtpB 与分枝杆菌细胞的 Cu+ 转运相关，可能发挥与铜解毒不同的作用。