NOVEL TARGETS OF THE SULFHYDRYL : CYTOCHROME C OXIDOREDUCTASE ALR

线粒体膜间空间（IMS）的二硫化物形成是建立和维持蛋白质结构、调节蛋白质功能和驱动酶反应作为反应周期的一部分的重要过程。线粒体二硫化物接力由两个核心组分ALR/Erv1和CHCHD4/Mia40组成，在IMS中催化二硫化物的形成。因此，CHCHD4对许多底物的IMS导入和氧化折叠至关重要。ALR的主要功能被认为与CHCHD4的再生有关，以维持其活性状态。为此，ALR接收来自CHCHD4的电子，并通过电子接力反应将它们传递给细胞色素c。我们假设人类ALR的作用超出了它最初提出的作为CHCHD4再生酶的作用。相反，我们建议将ALR作为IMS的中心电子中继站。我们最近在蛋白质组学方法中通过识别相互作用伙伴获得了ALR靶向多种不同蛋白质的见解。在这个项目中，我们将测试ALR是否在不同组织中发挥替代功能，并因此确定组织特异性底物相互作用。然后，我们将描述两个新的ALR靶点的ALR依赖氧化的机制，功能和生理后果。此外，我们将使用一组不同的ALR和CHCHD4靶标来研究CHCHD4和ALR处理底物的机制差异。总的来说，我们的工作将为线粒体二硫化物传递机制、线粒体膜间空间的生物学以及氧化蛋白折叠提供新的见解。

Disulfide formation in the mitochondrial intermembrane space (IMS) is an essential process that serves in establishing and maintaining protein structures, in regulating protein functions and in driving enzyme reactions as parts of reaction cycles. The mitochondrial disulfide relay, consisting of the two core components ALR/Erv1 and CHCHD4/Mia40, catalyzes disulfide formation in the IMS. CHCHD4 thereby is crucial for IMS import and oxidative folding of many substrates. The major function of ALR was mainly thought to involve regeneration of CHCHD4 to maintain it in its active state. To this end, ALR receives electrons from CHCHD4 and passes them on to cytochrome c in an electron relay reaction. We hypothesize that the role of human ALR expands beyond its originally proposed role as regenerating enzyme for CHCHD4. Instead, we propose that ALR serves as a central electron relay station in the IMS. We recently obtained insights that ALR targets a broad variety of different proteins by identifying interaction partners in proteomic approaches. With this project, we will test whether ALR exerts alternative functions in different tissues, and will therefore identify tissue-specific substrate interactions. We will then characterize the mechanistic, functional and physiological consequences of ALR-dependent oxidation for two novel ALR targets. Moreover, we will investigate the mechanistic differences between substrate handling by CHCHD4 and ALR using a set of different ALR and CHCHD4 targets.Collectively, our work will provide new insights into essential mitochondrial disulfide relay machinery, the biology of the mitochondrial intermembrane space, and into oxidative protein folding in general.