苜蓿中华根瘤菌 CCNWSX0020 中 P1B 型 ATP 酶的锌抗性机制。

Zinc Resistance Mechanisms of P1B-type ATPases in Sinorhizobium meliloti CCNWSX0020.

机构信息

State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A and F University, Yangling, Shaanxi, China.

College of Life Sciences, Nankai University, Tianjin, China.

出版信息

Sci Rep. 2016 Jul 5;6:29355. doi: 10.1038/srep29355.

The Sinorhizobium meliloti (S. meliloti) strain CCNWSX0020 displayed tolerance to high levels exposures of multiple metals and growth promotion of legume plants grown in metal-contaminated soil. However, the mechanism of metal-resistant strain remains unknown. We used five P1B-ATPases deletions by designating as ∆copA1b, ∆fixI1, ∆copA3, ∆zntA and ∆nia, respectively to investigate the role of P1B-ATPases in heavy metal resistance of S. meliloti. The ∆copA1b and ∆zntA mutants were sensitive to zinc (Zn), cadmium (Cd) and lead (Pb) in different degree, whereas the other mutants had no significant influence on the metal resistance. Moreover, the expression of zntA was induced by Zn, Cd and Pb whereas copA1b was induced by copper (Cu) and silver (Ag). This two deletions could led to the increased intracellular concentrations of Zn, Pb and Cd, but not of Cu. Complementation of ∆copA1b and ∆zntA mutants showed a restoration of tolerance to Zn, Cd and Pb to a certain extent. Taken together, the results suggest an important role of copA1b and zntA in Zn homeostasis and Cd and Pb detoxification in S. meliloti CCNWSX0020.

苜蓿中华根瘤菌（S. meliloti）菌株 CCNWSX0020 对多种金属的高水平暴露具有耐受性，并能促进在受金属污染土壤中生长的豆科植物的生长。然而，金属抗性菌株的机制尚不清楚。我们通过设计将五个 P1B-ATPase 缺失，分别指定为 ∆copA1b、∆fixI1、∆copA3、∆zntA 和 ∆nia，以研究 P1B-ATPase 在 S. meliloti 重金属抗性中的作用。∆copA1b 和 ∆zntA 突变体对锌（Zn）、镉（Cd）和铅（Pb）的敏感性不同，而其他突变体对金属抗性没有显著影响。此外，zntA 的表达受 Zn、Cd 和 Pb 的诱导，而 copA1b 的表达则受铜（Cu）和银（Ag）的诱导。这两个缺失会导致细胞内 Zn、Pb 和 Cd 的浓度增加，但 Cu 的浓度没有增加。∆copA1b 和 ∆zntA 突变体的互补显示出对 Zn、Cd 和 Pb 的耐受性在一定程度上得到恢复。综上所述，结果表明 copA1b 和 zntA 在 S. meliloti CCNWSX0020 中的 Zn 稳态和 Cd 和 Pb 解毒中起着重要作用。