Department of Genetics, University of Leicester, Leicester LE1 7RH, UK.
Mol Microbiol. 2011 Sep;81(5):1255-70. doi: 10.1111/j.1365-2958.2011.07758.x. Epub 2011 Jul 19.
High levels of copper are toxic and therefore bacteria must limit free intracellular levels to prevent cellular damage. In this study, we show that a number of pneumococcal genes are differentially regulated by copper, including an operon encoding a CopY regulator, a protein of unknown function (CupA) and a P1-type ATPase, CopA, which is conserved in all sequenced Streptococcus pneumoniae strains. Transcriptional analysis demonstrated that the cop operon is induced by copper in vitro, repressed by the addition of zinc and is autoregulated by the copper-responsive CopY repressor protein. We also demonstrate that the CopA ATPase is a major pneumococcal copper resistance mechanism and provide the first evidence that the CupA protein plays a role in copper resistance. Our results also show that copper homeostasis is important for pneumococcal virulence as the expression of the cop operon is induced in the lungs and nasopharynx of intranasally infected mice, and a copA(-) mutant strain, which had decreased growth in high levels of copper in vitro, showed reduced virulence in a mouse model of pneumococcal pneumonia. Furthermore, using the copA(-) mutant we observed for the first time in any bacteria that copper homeostasis also appears to be required for survival in the nasopharynx.
高水平的铜是有毒的，因此细菌必须将细胞内的游离水平限制在一定范围内，以防止细胞损伤。在本研究中，我们表明，许多肺炎链球菌基因受到铜的差异调节，包括一个编码 CopY 调节剂、一种未知功能蛋白（CupA）和一种 P1 型 ATP 酶的操纵子，CopA 在所有已测序的肺炎链球菌株中都保守。转录分析表明，cop 操纵子在体外受铜诱导，锌的加入抑制其表达，并受铜响应的 CopY 阻遏蛋白的自身调控。我们还证明，CopA ATP 酶是肺炎链球菌的主要铜抗性机制，并首次提供证据表明 CupA 蛋白在铜抗性中发挥作用。我们的结果还表明，铜稳态对肺炎链球菌的毒力很重要，因为 cop 操纵子在经鼻腔感染的小鼠肺部和鼻咽部表达，并且在体外高水平铜中生长能力下降的 copA(-)突变株在肺炎链球菌肺炎的小鼠模型中表现出毒力降低。此外，使用 copA(-)突变株，我们首次在任何细菌中观察到，铜稳态似乎也是在鼻咽部生存所必需的。
