The role of membrane scaffolds for the spatial organization and heterogeneity of the mitochondrial inner membrane

膜支架对线粒体内膜空间组织和异质性的作用

• 批准号: 426717136
• 负责人: Professor Dr. Thomas Langer
• 金额: --
• 依托单位: Max-Planck-Institut für Biologie des Alterns
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/426717136?language=en
• 关键词: role; membrane; scaffolds; spatial; organization

The mitochondrial inner membrane is a protein-rich, complex membrane structure, which serves as an important metabolic barrier in cells and houses numerous metabolic processes. Distinct functions are carried out in morphologically defined regions, such as protein translocation in the inner boundary membrane or the production of ATP via OXPHOS complexes in mitochondrial cristae. Moreover, increasing evidence suggests large functional heterogeneity at the nanoscale within the inner membrane. Multimeric membrane scaffold proteins of the SPFH-family, prohibitins (PHB1, PHB2) and the stomatin-like protein SLP2, form large ring complexes in the inner membrane, which are proposed to serve as lipid and protein scaffolds. These scaffold proteins assemble with AAA proteases at opposite membrane surfaces constituting proteolytic hubs in the inner membrane. Loss of PHB membrane domains severely impairs mitochondrial functions and is associated with neurodegeneration, obesity and kidney failure. During the last funding period, we have identified TMBIM5 (GHITM, MICS1) as a novel constituent of PHB membrane domains. Our functional analysis revealed that TMBIM5 acts both as a Ca2+/H+ exchanger and inhibitor of the m-AAA protease in the inner membrane. TMBIM5 thus couples the mitochondrial proton gradient with protein turnover rates to reshape the mitochondrial proteome and adjust the cellular metabolism. These findings suggest that spatially restricted, localized proteolysis contributes to the functional and structural heterogeneity of the inner membrane. We will therefore examine the role of membrane scaffolds and the TMBIM5-dependent proton gradient for the spatial regulation of proteolysis in the inner membrane. We will apply various advanced proteomic approaches to monitor localized proteolysis at PHB membrane domains, define the protein topology within these domains and examine the effect of TMBIM5 and the proton motif force on the stability of inner membrane proteins. Together, our experiments will further define regulatory circuits coupling protein turnover to the energetic status of mitochondria and unravel how localized proteolysis regulated by membrane scaffolds contributes to the functional heterogeneity of the inner membrane.

线粒体内膜是一种富含蛋白质的复杂膜结构，它是细胞中重要的代谢屏障，容纳了许多代谢过程。不同的功能在形态上定义的区域中进行，例如内界膜中的蛋白质易位或通过线粒体嵴中的OXPHOS复合物产生ATP。此外，越来越多的证据表明，在内膜内的纳米级的大的功能异质性。SPFH-家族的多聚体膜支架蛋白，白蛋白（PHB 1，PHB 2）和气孔蛋白样蛋白SLP 2，在内膜中形成大的环状复合物，其被提议用作脂质和蛋白质支架。这些支架蛋白与AAA蛋白酶在相对的膜表面组装，构成内膜中的蛋白水解枢纽。PHB膜结构域的丧失严重损害线粒体功能，并与神经变性、肥胖和肾衰竭相关。在上一个资助期间，我们已经确定了TMBIM 5（GHITM，MICS 1）作为PHB膜结构域的新成分。我们的功能分析表明，TMBIM 5作为一个Ca 2 +/H+交换和抑制剂的m-AAA蛋白酶在内膜。因此，TMBIM 5将线粒体质子梯度与蛋白质周转率偶联，以重塑线粒体蛋白质组并调节细胞代谢。这些研究结果表明，空间限制，本地化的蛋白水解有助于内膜的功能和结构的异质性。因此，我们将研究的作用，膜支架和TMBIM 5依赖的质子梯度的空间调节蛋白水解的内膜。我们将应用各种先进的蛋白质组学方法来监测本地化的蛋白水解在聚羟基丁酸膜结构域，定义这些结构域内的蛋白质拓扑结构，并检查TMBIM 5和质子基序力对内膜蛋白的稳定性的影响。总之，我们的实验将进一步定义耦合蛋白质周转的线粒体的充满活力的状态的监管电路，并解开如何本地化的蛋白水解膜支架调节有助于内膜的功能异质性。