Chaperone Function in Iron-Sulfur Protein Folding

描述：(申请人描述)含有铁-硫簇的蛋白质 具有重要的电子转移、催化和调节功能，但 Fe/S团簇形成和修复的细胞机制不是 为人所知。最近，一项结合了生化和遗传学的研究已经 涉及几个新的蛋白质在铁/S簇生物发生中的作用。在细菌中，这些 蛋白质编码在一个保守的基因簇中，该基因簇包括三个铁 硫簇组装基因(IscS、LscU、IscA)，两个热激同源基因 伴侣基因(hscA和hscB)和a(2Fe-2S)-铁氧还蛋白(FDX)。我们有 大肠杆菌中相应蛋白的高效表达和纯化 Coli，并提出生物化学和结构研究相结合的方法 探讨它们在Fe/S团簇组装和掺入中的作用 铁/S-聚集成蛋白质。 建议的生化研究将涉及1)转移的机制 硫化物从半胱氨酸脱硫酶LSCs到Fe/S模板蛋白LSCU， 2)ISCA作为一种新的护航金属络合物在提供铁 团簇组装，3)LSCU及其(2Fe-2S)络合物与分子间的相互作用 Hsc66/H3c20伴侣系统；4)Fe/S团簇向受体的转移 载脂蛋白。还提出了蛋白质的X射线结晶学研究。 以提供有关分子机制的结构洞察力。 这些研究应该能更好地理解分子机制。 参与了Fe/S团簇的组装。此外，看起来很可能 铁/S-蛋白的组装在真核生物中存在一种保守的机制，并且 这些研究的发现可能会为研究人类免疫缺陷的分子基础提供新的见解。 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.