Molecular analysis of Shy1/Surf1 function in early steps of cytochrome c oxidase assembly

线粒体内膜的细胞色素氧化酶由线粒体和核编码亚基组装而成。装配过程中的缺陷导致了人类严重的神经肌肉疾病。Shy1/SURF1是一个组装因子，其作用尚不明确，可将血红素a3整合到Cox1中。人体Shy1/SURF1功能缺陷导致细胞色素氧化酶缺乏和Leigh综合征。我们分析的目的是了解Shy1/SURF1在组装过程中的分子功能，以及它的功能丧失如何导致细胞色素氧化酶缺乏。我们的分析表明，Shy1/SURF1一方面介导了组装过程的进展，另一方面直接或间接地参与了Cox1的翻译调控。在这个项目中，我们将评估翻译调节因子Mss51如何在其调控周期中被激活和失活，以了解该过程如何受到Shy1/SURF1的影响。此外，我们将讨论Shy1/SURF1如何与线粒体的血红素合成机制合作。我们将分析是否在Shy1和Cox15之间形成配合物，以及血红素合成中的缺陷如何影响Shy1与组装中间体的相互作用。在人类细胞中鉴定出一种在后生动物中保守的SURF1相互作用蛋白，使我们能够确定SURF1是否通过组装中间体影响人类线粒体的线粒体翻译。对于这些分析，我们将使用SURF1敲除小鼠模型。这些分析将为细胞色素氧化酶的生物发生机制提供重要的见解，并使我们更好地了解Leigh综合征的病理生化基础。

The cytochrome oxidase of the inner mitochondrial membrane assembles from mitochondria- and nuclear-encoded subunits. Defects in the assembly process lead to severe neuromuscular disorders in human. Shy1/SURF1 is an assembly factor with a yet undefined role for incorporation of haem a3 into Cox1. Defects of Shy1/SURF1 function cause cytochrome oxidase deficiency and Leigh Syndrome in human. The goal of our analyses is to understand the molecular function of Shy1/SURF1 in the assembly process and how a loss of its function causes cytochrome oxidase deficiency. Our analyses have demonstrated that Shy1/SURF1 mediates progression of the assembly process on the one hand while on the other hand it plays a direct or indirect role for translational regulation of Cox1. In this project we will assess how the translational regulator Mss51 is activated and inactivated in its regulatory cycle in order to understand how this process is affected by Shy1/SURF1. Moreover, we will address how Shy1/SURF1 cooperates with the haem synthesis machinery of mitochondria. We will analyze if complexes are formed between Shy1 and Cox15 and how defects in haem synthesis affect interaction of Shy1 with assembly intermediates. The identification of a SURF1 interacting protein in human cells, which is conserved in metazoa, allows us to address if SURF1 affects mitochondrial translation in human mitochondria through assembly intermediates. For these analyses we will make use of a SURF1 knockout mouse model. These analyses will provide important insight into the mechanism of cytochrome oxidase biogenesis and allow us to better understand the patho-biochemistry underlying Leigh Syndrom.