Spatial and Temporal Resolution of the Plasticity in Mitochondrial Proteomes

 描述（由申请人提供）：后生动物已经进化出各种防御机制，以保护自己免受压力的有害后果。许多应激反应机制需要改变其蛋白质组的组成，这是一种在衰老过程中可能丢失或加剧的重塑。这种重塑通常包括增强应激反应蛋白和分子伴侣的网络，其中许多蛋白和分子伴侣针对特定的亚细胞区室或细胞器，包括线粒体。虽然线粒体具有分离的基因组，但其蛋白质组主要由在细胞核中编码并在细胞质中翻译的蛋白质组成。大多数线粒体蛋白需要线粒体靶向序列（MTS）来驱动它们输入线粒体。关于蛋白质是否发生易位的决定通常包含在蛋白质本身的靶向序列内。令人惊讶的是，很大比例的蛋白质，含有MTS序列被预测为双重定位在其他亚细胞区室以及。值得注意的是，许多双重定位的蛋白质实际上是线粒体应激反应蛋白或伴侣蛋白。我们假设：1）线粒体蛋白质的一个子集的双重定位允许线粒体蛋白质组的组成具有适应性可塑性，2）应激反应蛋白的特定MTS将使其输入老年线粒体群体的效率发生偏差。在本项目中，线虫C. elegans将被用来调查这些假设。在这项提案中，我们将采取一系列方法来了解双靶向蛋白质如何在生物体的整个生命周期中在亚细胞区室之间波动，以及靶向信号如何作为调节这些蛋白质的输入和定位的主动机制。

 DESCRIPTION (provided by applicant): The metazoan has evolved various defensive mechanisms to protect itself against the detrimental consequences of stress. Many of the stress responsive mechanisms require altering the composition of their proteomes, a remodeling that may either become lost or exacerbated during the course of aging. This remodeling often includes enhancing the networks of stress responsive proteins and chaperones, many of which are targeted for specific subcellular compartments or organelles, including mitochondria. Though possessing an isolated genome, mitochondria have a proteome that is predominantly composed of proteins encoded in the nucleus and translated in the cytoplasm. A mitochondrial targeting sequence (MTS) is required on the majority of mitochondrial proteins to drive their import into mitochondria. The decision as to whether a protein becomes translocated or not is often contained within the targeting sequence of the protein itself. Surprisingly, a large percentage of proteins that contain an MTS sequence are predicted as dually localized in other subcellular compartments as well. Notably, a number of dually localized proteins are actually mitochondrial stress responsive proteins or chaperones. We hypothesize that 1) the dual localization of a subset of mitochondrial proteins allows for an adaptive plasticity in the composition of the mitochondrial proteome, and 2) the specific MTS of a stress-responsive protein will bias the efficiency of its import toward populations of aged mitochondria. In this project, the nematode C. elegans will be used to investigate these hypotheses. In this proposal, we will undertake a series of methods to both understand how dually targeted proteins fluctuate between subcellular compartments across the lifespan of an organism, and how the targeting signal serves as an active mechanism by which the import and localization of these proteins are regulated.