Functional characterization of mitochondrial AAA proteases in Saccharomyces cerevisiae

AAA蛋白酶是一类保守的膜结合atp依赖性蛋白酶，普遍存在于真核细胞的线粒体和叶绿体中。本课题拟研究酵母（Saccharomyces cerevisiae）线粒体中两种AAA蛋白酶的功能。这两种蛋白酶形成了一个膜集成的质量控制系统，其活性对线粒体的生物发生和细胞生长至关重要。我们将研究这些蛋白酶引导多聚膜蛋白周转的机制。了解底物多肽是如何被AAA蛋白酶识别和结合，并随后从膜双分子层脱位进行蛋白水解的，将是特别有趣的。我们研究的另一个重点将是鉴定线粒体中AAA蛋白酶的内源性底物。遗传学和蛋白质组学方法将用于鉴定和表征在细胞器生物发生过程中具有潜在调节功能的短寿命线粒体蛋白。这些研究不仅进一步加深了我们对酵母中AAA蛋白酶突变相关的多性缺陷的理解，而且还为人类AAA蛋白酶失活引起的神经退行性疾病的发病机制提供了新的见解。

AAA proteases are a conserved class of membrane-bound ATP-dependent proteases that are ubiquitously present in mitochondria and chloroplasts of eukaryotic cells. In the proposed research project, the function of two AAA proteases in mitochondria of the yeast Saccharomyces cerevisiae will be studied. Both proteases form a membrane-integrated quality control system whose activity is essential for mitochondrial biogenesis and cell growth. We will examine mechanisms guiding the turnover of polytopic membrane proteins by these proteases. It will be of particular interest to understand how substrate polypeptides are recognized and bound by AAA proteases and subsequently dislocated from the membrane bilayer for proteolysis. Another major focus of our studies will be the identification of endogenous substrates of AAA proteases in mitochondria. A genetic and a proteomic approach will be used to identify and characterize short-lived mitochondrial proteins with potential regulatory functions during organellar biogenesis. These studies should not only further our understanding of the pleiotropic defects associated with AAA protease mutations in yeast, but should also provide new insights into the pathogenesis of a neurodegenerative disorder caused by an inactivation of an AAA protease in humans.