Sulphur shuttling across a chaperone during molybdenum cofactor maturation
Sulphur shuttling across a chaperone during molybdenum cofactor maturation
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DOI：
10.1038/ncomms7148
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发表时间：
2015-02-01
影响因子：
16.6
通讯作者：
Walburger, Anne
中科院分区：
文献类型：
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作者：
Arnoux, Pascal;Ruppelt, Christian;Walburger, Anne
甲酸脱氢酶（FDHs）引起了人们的兴趣，因为它们是一种天然催化剂，可以隔离大气中的二氧化碳，产生可能用作燃料的还原碳化合物。FDHs在大肠杆菌中的活性严格要求硫转移酶EcFdhD，该酶可能将硫从IscS转移到FDHs的钼辅因子（Mo-bisPGD）。在这里，我们表明EcFdhD在体内与Mo-bisPGD结合，并对gdp具有亚微摩尔亲和力-作为钼辅助因子核苷酸部分的替代品。EcFdhD与GDP配合物的晶体结构显示两个对称的结合位点位于二聚体的同一面上。这些结合位点通过一个类似隧道的空腔连接到二聚体的对面，在那里存在两个动态环，每个环都含有两个功能重要的半胱氨酸残基。在结构导向诱变的基础上，我们提出了Mo-bisPGD的硫化机制模型，其中硫原子穿梭于伴侣二聚体之间。
Formate dehydrogenases (FDHs) are of interest as they are natural catalysts that sequester atmospheric CO2, generating reduced carbon compounds with possible uses as fuel. FDHs activity in Escherichia coli strictly requires the sulphurtransferase EcFdhD, which likely transfers sulphur from IscS to the molybdenum cofactor (Mo-bisPGD) of FDHs. Here we show that EcFdhD binds Mo-bisPGD in vivo and has submicromolar affinity for GDP-used as a surrogate of the molybdenum cofactor's nucleotide moieties. The crystal structure of EcFdhD in complex with GDP shows two symmetrical binding sites located on the same face of the dimer. These binding sites are connected via a tunnel-like cavity to the opposite face of the dimer where two dynamic loops, each harbouring two functionally important cysteine residues, are present. On the basis of structure-guided mutagenesis, we propose a model for the sulphuration mechanism of Mo-bisPGD where the sulphur atom shuttles across the chaperone dimer.