Dynamic regulation of the modular assembly of the mitochondrial respiratory chain

线粒体呼吸链通过氧化磷酸化过程产生三磷酸腺苷，在细胞能量代谢中起着核心作用。几种蛋白质和不同的辅助因子构成了单独的呼吸链复合体，这些复合体进一步组装成所谓的超复合体。这些复合体的活性适应细胞的新陈代谢需求。单个复合体的生物发生和超复合体的组装需要几个组装因子。生物发生过程中的缺陷或呼吸链的活性缺陷会导致活性氧物种和氧化应激的产生增加，并导致严重的人类疾病。呼吸链复合体还依赖于线粒体标志性脂类心磷脂(CL)的稳定性，并反过来影响CL亚种的分布。我们对动态调节复合体IV组装和超复合体适应变化代谢需求的分子机制的了解仍然有限。此外，组装因子和CL亚种分布之间可能的相互作用到目前为止还没有被研究过。我们已经鉴定出新的线粒体蛋白Min8，它在呼吸链复合体IV的生物发生中发挥作用。我们的初步数据显示，Min8蛋白水平是动态调节的，并在代谢转变为呼吸生长条件时强烈增加。交联分析表明，Min8与络合物IV在同一位置与组成表达的超络合物组装因子Rcf1和Rcf2结合。因此，我们假设存在不同的复合体IV亚模块，它们组装成超复合体取决于细胞的代谢需求。由于其蛋白质水平的动态变化，Min8可能作为中央质量控制，调节不同的复合体IV亚模块的掺入超复合体。此外，我们还发现，组装因子Rcf1和Rcf2的缺失会导致CL亚种组成的变化，现在我们想要研究Rcf1和Rcf2作为脂质伴侣的可能的新作用。我们将使用模式生物酿酒酵母来验证我们的假设。综上所述，我们的项目旨在揭示不同复合体IV亚模块及其组装成超复合体的生物发生和调控的分子机制。这些分析将有助于我们对线粒体内这一基本且高度保守的能量转换过程的初步了解。

The mitochondrial respiratory chain plays a central role in cellular energy metabolism by generating ATP through the process of oxidative phosphorylation. Several proteins and diverse co-factors build up the individual respiratory chain complexes that further assemble into so called supercomplexes. The activity of these complexes is adapted to the metabolic needs of the cell. Several assembly factors are required for the biogenesis of the individual complexes and assembly of the supercomplexes. Defects during the biogenesis or in the activity of the respiratory chain trigger increased generation of reactive oxygen species and oxidative stress and result in severe human diseases. The respiratory chain complexes also depend on the mitochondrial signature lipid Cardiolipin (CL) for their stability and can in turn effect CL subspecies distribution. Our knowledge of the molecular mechanisms dynamically regulating the assembly of complex IV and the adaptation of the supercomplexes upon changed metabolic demands is still limited. Also, a possible interplay between assembly factors and the distribution of CL subspecies has not been investigated so far. We have identified the novel mitochondrial protein Min8, which plays a role in the biogenesis of complex IV of the respiratory chain. Our preliminary data reveal that Min8 protein levels are dynamically regulated and strongly increase upon metabolic shift to respiratory growth conditions. Crosslinking analysis shows that Min8 associates with complex IV at the same position as the supercomplex assembly factors Rcf1 and Rcf2, that are constitutively expressed. Therefore, we postulate that different complex IV submodules exist and that their assembly into supercomplexes is dependent on the metabolic needs of the cell. Due to its dynamically adapting protein levels Min8 might function as central quality control that regulates the incorporation of different complex IV submodules into the supercomplexes. Furthermore, we have discovered that loss of the assembly factors Rcf1 and Rcf2 results in changes in the composition of CL subspecies and we now want to investigate a possible new role of Rcf1 and Rcf2 as lipid chaperones. We will investigate our hypotheses using the model organism S. cerevisiae.In summary, our project aims to uncover the molecular mechanisms underlying the biogenesis and regulation of different complex IV submodules and their assembly into supercomplexes. The analyses will contribute elementary to our understanding of this fundamental and highly conserved process of energy conversion within mitochondria.