Chloroplast monothiol glutaredoxins as scaffold proteins for the assembly and delivery of [2Fe-2S] clusters
Chloroplast monothiol glutaredoxins as scaffold proteins for the assembly and delivery of [2Fe-2S] clusters
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DOI：
10.1038/emboj.2008.50
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发表时间：
2008-04-09
期刊：
影响因子：
11.4
通讯作者：
Rouhier, Nicolas
中科院分区：
文献类型：
--
作者：
Bandyopadhyay, Sibali;Gama, Filipe;Rouhier, Nicolas
谷氧还蛋白（Glutaredoxins，Grxs）是一种能够还原二硫键或蛋白质-谷胱甘肽混合二硫化物的小分子氧化还原酶。在高等植物中有30多个不同的grx基因表达，但目前对它们的功能多样性知之甚少。这项研究提出了生物化学和光谱证据，在两个异源表达的叶绿体Grxs，GrxS 14和GrxS 16，并在体外半胱氨酸天冬氨酸酶介导的组装的一个相同的[2Fe-2S]簇在apo-GrxS 14。这些Grx具有与酵母Grx 5相同的单硫醇CGFS活性位点，并且两者都能够补充在Fe-S簇组装中有缺陷的酵母grx 5突变体。在体外动力学研究监测的CD光谱表明，[2Fe-2S]集群GrxS 14的快速和定量转移到脱辅基叶绿体铁氧还蛋白。这些数据表明，叶绿体CGFS Grxs有潜力作为支架蛋白的组装[2Fe-2S]集群，可以完整地转移到生理相关的受体蛋白。或者，它们可以在预先形成的Fe-S簇的储存和/或递送中或在叶绿体Fe-S簇组装机器的调节中起作用。
Glutaredoxins (Grxs) are small oxidoreductases that reduce disulphide bonds or protein-glutathione mixed disulphides. More than 30 distinct grx genes are expressed in higher plants, but little is currently known concerning their functional diversity. This study presents biochemical and spectroscopic evidence for incorporation of a [2Fe-2S] cluster in two heterologously expressed chloroplastic Grxs, GrxS14 and GrxS16, and in vitro cysteine desulphurase-mediated assembly of an identical [2Fe-2S] cluster in apo-GrxS14. These Grxs possess the same monothiol CGFS active site as yeast Grx5 and both were able to complement a yeast grx5 mutant defective in Fe-S cluster assembly. In vitro kinetic studies monitored by CD spectroscopy indicate that [2Fe-2S] clusters on GrxS14 are rapidly and quantitatively transferred to apo chloroplast ferredoxin. These data demonstrate that chloroplast CGFS Grxs have the potential to function as scaffold proteins for the assembly of [2Fe-2S] clusters that can be transferred intact to physiologically relevant acceptor proteins. Alternatively, they may function in the storage and/or delivery of preformed Fe-S clusters or in the regulation of the chloroplastic Fe-S cluster assembly machinery.