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首页> 外文期刊>Journal of bacteriology >The Glutathione/Glutaredoxin System Is Essential for Arsenate Reduction in Synechocystis sp. Strain PCC 6803
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The Glutathione/Glutaredoxin System Is Essential for Arsenate Reduction in Synechocystis sp. Strain PCC 6803

机译：谷胱甘肽/谷胱甘肽毒素系统对于降低集胞藻中的砷含量至关重要。应变PCC 6803

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Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by an operon of three genes in which arsC codes for an arsenate reductase with unique characteristics. Here we describe the identification of two additional and nearly identical genes coding for arsenate reductases in Synechocystis sp. strain PCC 6803, which we have designed arsI1 and arsI2, and the biochemical characterization of both ArsC (arsenate reductase) and ArsI. Functional analysis of single, double, and triple mutants shows that both ArsI enzymes are active arsenate reductases but that their roles in arsenate resistance are essential only in the absence of ArsC. Based on its biochemical properties, ArsC belongs to a family that, though related to thioredoxin-dependent arsenate reductases, uses the glutathione/glutaredoxin system for reduction, whereas ArsI belongs to the previously known glutaredoxin-dependent family. We have also analyzed the role in arsenate resistance of the three glutaredoxins present in Synechocystis sp. strain PCC 6803 both in vitro and in vivo. Only the dithiolic glutaredoxins, GrxA (glutaredoxin A) and GrxB (glutaredoxin B), are able to donate electrons to both types of reductases in vitro, while GrxC (glutaredoxin C), a monothiolic glutaredoxin, is unable to donate electrons to either type. Analysis of glutaredoxin mutant strains revealed that only those lacking the grxA gene have impaired arsenic resistance.
机译：拟南芥的砷抗性。 PCC 6803菌株由三个基因的操纵子介导，其中 arsC 编码具有独特特征的砷酸还原酶。在这里，我们描述了两个 Synechocystis sp中编码砷还原酶的几乎相同的基因的鉴定。我们设计了 arsI1 和 arsI2 的PCC 6803菌株，以及ArsC（砷酸还原酶）和ArsI的生化特性。对单，双和三突变体的功能分析表明，两种ArsI酶都是有活性的砷酸盐还原酶，但是它们在砷酸盐抗性中的作用只有在没有ArsC的情况下才是必需的。基于其生化特性，ArsC属于一个家族，尽管与依赖硫氧还蛋白的砷酸盐还原酶有关，但仍使用谷胱甘肽/谷氨酰胺还原酶系统进行还原，而ArsI属于先前已知的谷氨酰胺依赖蛋白家族。我们还分析了 Synechocystis sp。中三种谷氨酰胺毒素在砷抗性中的作用。株PCC 6803在体外和体内。只有二​​硫代戊二糖毒素GrxA（glutaredoxin A）和GrxB（戊糖毒素B）能够在体外向两种类型的还原酶提供电子，而GrxC（戊二糖毒素C）是单硫代戊二糖毒素，不能向任何一种类型提供电子。对戊二醛突变菌株的分析表明，只有缺乏 grxA 基因的菌株才具有砷抗性受损。

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