Chaperone Function in Iron-Sulfur Protein Folding

描述（由申请人提供）：含有铁硫团簇的蛋白质具有重要的电子转移、催化和调节功能，但铁硫团簇形成和引入蛋白质的细胞机制尚不清楚。最近的研究发现了参与Fe-S蛋白生物合成的新蛋白质，它们的作用和相互作用正在被确定。在细菌中，这些蛋白质中的一些编码在一个保守的基因簇中，该基因簇编码三种Fe-S簇组装组分（IscS, IscU, IscA）和一个专门的伴侣/共同伴侣系统（HscA和HscB）。我们已经从大肠杆菌中产生了这些蛋白质的重组形式，并提出了生物化学、生物物理和结构研究，以研究它们在铁- s簇的组装和铁- s簇结合到蛋白质中的作用。

DESCRIPTION (provided by applicant): Proteins containing iron-sulfur clusters possess important electron transfer, catalytic, and regulatory functions, but the cellular mechanisms by which the Fe-S clusters are formed and introduced into proteins are not well understood. Recent studies have identified novel proteins that participate in Fe-S protein biosynthesis, and their roles and interactions are being defined. In bacteria several of these proteins are encoded in a conserved gene cluster that encodes three Fe-S cluster assembly components (IscS, IscU, IscA), and a specialized chaperone/co-chaperone system (HscA and HscB). We have produced recombinant forms of each of these proteins from Escherichia coli, and propose biochemical, biophysical and structural studies to investigate their roles in the assembly of Fe-S-clusters and the incorporation of Fe-S clusters into proteins. The proposed studies will address 1) the mechanism of transfer of sulfur from the cysteine desulfurase IscS to the transient Fe-S scaffold protein IscU, 2) the role of IscA in iron binding and cluster assembly, 3) interactions of IscU with the HscA/HscB chaperone system, and 4) the transfer of Fe-S clusters to acceptor apo-proteins. Additional studies on the interaction of HscA with peptides will also be carried out to investigate general principles of hsp70-substrate interactions. Results of these studies will provide a better understanding of molecular mechanisms involved in the biogenesis of Fe-S proteins. Furthermore, a similar conserved mechanism of Fe-S protein assembly occurs in eukaryotes, and the findings may provide insight into the molecular basis of human diseases such as those associated with mitochondrial myopathies.