Alternative periplasmic copper-resistance mechanisms in Gram negative bacteria
Alternative periplasmic copper-resistance mechanisms in Gram negative bacteria
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DOI：
10.1111/j.1365-2958.2009.06763.x
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发表时间：
2009-07-01
影响因子：
3.6
通讯作者：
Soncini, Fernando C.
中科院分区：
文献类型：
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作者：
Pontel, Lucas B.;Soncini, Fernando C.
细菌进化出了不同的系统来严格控制胞质和包膜铜浓度以满足其需求，同时避免铜毒性。我们之前已经证明，与大肠杆菌一样，沙门氏菌提示系统可以保护细胞质免受铜过量的影响。另一方面，尽管沙门氏菌缺乏 CusCFBA 周质铜流出系统，但它在厌氧条件下可以支持比大肠杆菌更高的铜浓度。在这里，我们表明沙门氏菌线索调节子也负责控制厌氧中的铜毒性。我们确定这种情况下的抵抗需要一个名为cueP的新型CueR控制基因。 DeltacuP突变体在缺氧的情况下对铜高度敏感，但在有氧条件下表现出微弱的表型，除非其他铜抗性基因也被删除，类似于大肠杆菌CusCFBA的行为。含有受 CueR 调控的 CueP 同源物的物种没有功能性 CusR/CusS 依赖的 Cus 编码操纵子。相反，携带 CusR/CusS 调节的 cus 操纵子的物种没有cueP 同源物。更重要的是，我们发现 CueR 控制的cueP 表达增加了 Delta cus 大肠杆菌的铜抗性。我们假设 CueP 可以在功能上取代 Cus 复合物来抵抗周质铜，特别是在厌氧条件下。
Bacteria have evolved different systems to tightly control both cytosolic and envelope copper concentration to fulfil their requirements and at the same time, avoid copper toxicity. We have previously demonstrated that, as in Escherichia coli, the Salmonella cue system protects the cytosol from copper excess. On the other hand, and even though Salmonella lacks the CusCFBA periplasmic copper efflux system, it can support higher copper concentrations than E. coli under anaerobic conditions. Here we show that the Salmonella cue regulon is also responsible for the control of copper toxicity in anaerobiosis. We establish that resistance in this condition requires a novel CueR-controlled gene named cueP. A Delta cueP mutant is highly susceptible to copper in the absence of oxygen, but shows a faint phenotype in aerobic conditions unless other copper-resistance genes are also deleted, resembling the E. coli CusCFBA behaviour. Species that contain a cueP homologue under CueR regulation have no functional CusR/CusS-dependent Cus-coding operon. Conversely, species that carry a CusR/CusS-regulated cus operon have no cueP homologues. Even more, we show that the CueR-controlled cueP expression increases copper resistance of a Delta cus E. coli. We posit that CueP can functionally replace the Cus complex for periplasmic copper resistance, in particular under anaerobic conditions.