Spatial and Temporal Resolution of the Plasticity in Mitochondrial Proteomes

 描述(申请人提供)：后生动物已经进化出各种防御机制来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，这种重塑可能会在衰老过程中丢失或加剧。这种重塑通常包括增强应激反应蛋白和伴侣蛋白的网络，其中许多针对特定的亚细胞隔室或细胞器，包括线粒体。虽然线粒体拥有一个孤立的基因组，但它的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)才能驱动它们进入线粒体。蛋白质是否移位的决定通常包含在蛋白质本身的靶向序列中。令人惊讶的是，有很大比例的含有MTS序列的蛋白质被预测为双重定位于其他亚细胞隔间。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)线粒体蛋白质子集的双重定位允许线粒体蛋白质组组成的适应性可塑性，以及2)应激反应蛋白的特定MTS将使其导入的效率偏向于老化的线粒体群体。在这个项目中，线虫线虫将被用来研究这些假设。在这项提案中，我们将采用一系列方法来了解双靶向蛋白质如何在生物体整个生命周期的亚细胞间波动，以及靶向信号如何作为一种主动机制来调节这些蛋白质的输入和定位。

 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.