Mitochondrial cysteine desulfurase

半胱氨酸脱硫酶在从半胱氨酸中释放硫，形成 共价过硫化物，并将过硫化物硫导向生物关键受体，例如 铁硫团簇(Fe-S)和硫代化的tRNA。半胱氨酸脱硫酶的活性不能 被外源供应的硫化物或其他硫代谢酶取代，因此 半胱氨酸脱硫酶是细胞存活所必需的。真核细胞半胱氨酸脱硫酶编码 由单个核基因决定，主要存在于线粒体中。在酿酒酵母中 线粒体，半胱氨酸脱硫酶蛋白Nfs1组装在一个大的蛋白质复合体中，与 最近发现了一种名为Isd11的特殊辅助蛋白。我们发现Isd11是必需的 Nfs1半胱氨酸脱硫酶活性。因此，在细菌中同时表达的Nfs1和Isd11是 组装成活性络合物，而这些单独表达的成分是非活性的。 在这里，我们建议表征活性的Nfs1/Isd11复合体，以及其半胱氨酸的调节 铁-S簇支架蛋白的脱硫酶活性。目标1是确定酵母菌的作用 Isd11在具有活性的Nfs1/Isd11半胱氨酸脱硫酶复合体中。实验将使用以下工具进行 细菌表达和纯化的蛋白质，也在更生理的背景下使用分离的 完整的线粒体。目标2是表征Nfs1/Isd11上过硫硫的形成。 分离完整的线粒体，重点研究ISU的D37A突变的调节作用。 这一意义源于半胱氨酸脱硫酶对全人类生存能力的重要作用。 细胞。该酶主要存在于线粒体中，是铁-S簇合成所必需的 和线粒体中的tRNA硫基化，两者都是必需的过程。特定身份的识别 铁-S簇组装缺陷引起的疾病(如弗里德里希共济失调、铁粒母细胞 贫血和线粒体肌病)只是冰山一角。最近发现了一种 Fe-S簇在DNA修复和基因组稳定性中的关键作用提示半胱氨酸脱硫酶 都参与了这些过程。

Cysteine desulfurases perform essential functions in releasing sulfur from cysteine, forming a covalent persulfide, and channeling the persulfide sulfur to biologically critical recipients e.g. ironsulfur (Fe-S) clusters and thiolated tRNAs. The activity of cysteine desulfurase cannot be replaced by exogenously supplied sulfide or by other sulfur metabolizing enzymes, and thus cysteine desulfurase is essential for cell viability. The eukaryotic cysteine desulfurase is encoded by a single nuclear gene and is found primarily in mitochondria. In Saccharomyces cerevisiae mitochondria, the cysteine desulfurase protein Nfs1 is assembled in a large protein complex with a recently identified special accessory protein called Isd11. We found that Isd11 is required for Nfs1 cysteine desulfurase activity. Thus, Nfs1 and Isd11 expressed together in bacteria are assembled into an active complex, while these components expressed separately are inactive. Here we propose to characterize the active Nfs1/Isd11 complex, and regulation of its cysteine desulfurase activity by Fe-S cluster scaffold proteins, Isu. Aim 1 is to determine the role of yeast Isd11 in the active Nfs1/Isd11 cysteine desulfurase complex. Experiments will be performed using bacterial expressed and purified proteins, and also in a more physiological context using isolated intact mitochondria. Aim 2 is to characterize formation of persulfide sulfur on Nfs1/Isd11 in isolated intact mitochondria, with focus on the regulatory effect of the D37A mutation of Isu. The significance derives from the essential role of cysteine desulfurase for viability of all human cells. The enzyme is found primarily in mitochondria and is required for Fe-S cluster synthesis and tRNA thiolation in mitochondria, both are essential processes. The identification of specific diseases arising from defective Fe-S cluster assembly (e.g. Friedreich's ataxia, sideroblastic anemia, and mitochondrial myopathy) represents the tip of the iceberg. The recent discovery of a key role of Fe-S clusters in DNA repair and genome stability suggests that cysteine desulfurases are involved in these processes.