Bacteria, especially those living in soils, are in constant contact with metals. Transition metals like Fe or Zn, are required for proper growth. Some other metals like Cd or Hg are only toxic. Several systems exist to detoxify cells when these metals are present in concentrations harmful to biological systems. The expression of these systems is under control of specialized regulatory proteins able to detect metals and to regulate cognate detoxifying systems. In this work we report on the characterisation of the metallo-regulator CadR from Pseudomonas putida KT2440. By using gene reporter assays, we investigated the repertoire of metals detected by CadR. We show that CadR is much more responsive to Hg than to Cd, as compared to CadR from P. putida 06909. CadR from P. putida KT2440 differs in only 3 amino-acids in its metal-binding domain with respect to CadR from P. putida 06909. We show that these residues are important determinants of metal selectivity by engineering a modified CadR.

中文翻译：

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恶臭假单胞菌CadRs之间的原始序列差异驱动特异性。

细菌，特别是生活在土壤中的细菌，与金属不断接触。适当的生长需要像Fe或Zn这样的过渡金属。某些其他金属（例如Cd或Hg）仅具有毒性。当这些金属以对生物系统有害的浓度存在时，存在用于解毒细胞的几种系统。这些系统的表达受能够检测金属和调节同源解毒系统的专门调节蛋白的控制。在这项工作中，我们报告了恶臭假单胞菌KT2440的金属调控因子CadR的表征。通过使用基因报告基因检测，我们调查了CadR检测到的金属库。我们显示，与来自恶臭假单胞菌06909的CadR相比，CadR对Hg的响应性强于对Cd的响应。