Chaperone Function in Iron-Sulfur Protein Folding

描述：（申请人的描述）含铁-硫簇的蛋白质 具有重要的电子传递、催化和调节功能，但 Fe/S簇形成和修复的细胞机制不是 知道的最近，生物化学和遗传学研究的结合， 在Fe/S-簇生物发生中涉及几种新的蛋白质。在细菌中， 蛋白质编码在一个保守的基因簇，包括三个铁 硫簇组装基因（IscS，lscU，IscA），两个热休克同源基因 分子伴侣基因（hscA和hscB）和α（2Fe-2S）-铁氧还蛋白（fdx）。我们有 过量表达并纯化来自大肠杆菌的每种相应蛋白质 大肠杆菌，并建议结合生物化学和结构研究， 研究了它们在Fe/S团簇组装和掺入中的作用 Fe/S簇转化为蛋白质。 建议的生化研究将解决1）转移的机制， 从半胱氨酸脱硫酶lscS到Fe/S-模板蛋白lscU的硫化物， 2)IscA作为一种新的护送-金属伴侣在提供铁 3）lscU及其（2Fe-2S）络合物与 Hsc 66/H3 c20分子伴侣系统; 4）Fe/S团簇向受体的转移 脱辅基蛋白对蛋白质的X射线晶体学研究也提出了建议 以提供有关分子机制的结构见解。 这些研究应该能更好地理解分子机制 参与Fe/S团簇的组装。此外，似乎有可能， Fe/S蛋白组装的保守机制发生在真核生物中， 这些研究的结果可能会提供新的见解的分子基础 人类疾病如与线粒体肌病相关的疾病。

DESCRIPTION: (Applicant's Description) Proteins containing iron-sulfur Clusters possess important electron transfer, catalytic, and regulatory functions, but the cellular mechanism by which Fe/S-clusters are formed and repaired is not known. Recently, a combination of biochemical and genetic studies have implicated several novel proteins in Fe/S-cluster biogenesis. In bacteria these proteins are encoded in a conserved gene cluster that includes three iron sulfur cluster assembly genes (IscS, lscU, IscA), two heat shock cognate chaperone genes (hscA and hscB), and a (2 Fe-2S)-ferredoxin (fdx). We have overexpressed arid purified each of the corresponding proteins from Escherichia Coli, and propose a combination of bioch mical and structural studies to investigate their roles in the assembly of Fe/S-clusters and the incorporation of Fe/S-clusters into proteins. The biochemical studies proposed will address 1) the mechanism of transfer of sulfide from the cysteine desulfurase lscS to the Fe/S-template protein lscU, 2) the role of IscA as a novel escort- metalllochaperone in providing iron for cluster assembly, 3) the interaction of lscU and its (2Fe-2S) complex with the Hsc66/H3c20 chaperone system, and 4) the transfer of Fe/S clusters to acceptor apo-proteins. X-ray crystallographic studies on the proteins are also proposed to provide structural insights into he molecular mechanisms involved. These studies should provide a better understanding of molecular mechanisms involved in the assembly of Fe/S clusters. Furthermore, it appears likely that a conserved mechanism of Fe/S-protein assembly occurs in eukaryotes, and the findings of these studies may provide new insights into the molecular basis of human diseases such as those associated with mitochondrial myopathies.