Selective Autophagic Degradation of Peroxisomes in Yeast

描述（由申请人提供） 细胞中的主要降解区室是溶酶体（或其 相当于植物和酵母中的液泡）。尽管细胞已经进化到 多种机制将细胞成分递送到溶酶体，主要 途径是通过一系列统称为自噬的过程。经常的目标 过氧化物酶体是一种细胞器，含有必需的氧化 内切酶过氧化物酶体的数量、大小和酶含量变化迅速 在响应细胞的代谢需要时， 代谢型不再有用，它们被自噬选择性地去除。 流程. 这个项目的目标是了解控制 自噬一种遗传方法已经开始使用酵母毕赤酵母 pastoris作为一个模型系统。这种酵母有大量的过氧化物酶体， 在甲醇上培养，其在转移到 葡萄糖或乙醇。在上一届FIRCA期间，我们 成功地分离和表征了六种不同的巴斯德毕赤酵母突变体， 自噬过氧化物酶体降解缺陷的基因， 葡萄糖其中四个PDG基因被分离，DNA测序结果显示， 表明所有四种编码未知功能新蛋白质。 FIRCA这一持续提案的具体目标是：（1） 通过确定它们的亚细胞定位和搜索， （2）其他基因的产物与它们相互作用;（3）确定其他基因的产物与它们相互作用。 液泡分选途径受每个基因突变的影响;和（3） 开发和利用新的筛选和选择方法， 新PDG基因的突变体。这些研究结果将提供重要的 深入了解自噬机制。

DESCRIPTION (provided by applicant) The primary degradative compartment in the cell is the lysosome (or its equivalent in plants and yeasts, the vacuole). Although cells have evolved multiple mechanisms to deliver cellular components to the lysosome, the major route is via a set of processes collectively termed autophagy. Frequent targets of these processes are peroxisomes, organelles that contain essential oxidative enzymes. The number, size, and enzymatic content of peroxisomes change rapidly in response to a cell's metabolic needs, and when peroxisomes of a certain metabolic type are no longer useful, they are selectively removed by autophagic processes. The goal of this project is to understand the molecular mechanisms that control autophagy. A genetic approach has been initiated using the yeast Pichia pastoris as a model system. This yeast has large numerous peroxisomes when cultured on methanol, which are selectively autophagized upon transfer to either glucose or ethanol. During the period of our previous FIRCA, we succeeded in isolating and characterizing P. pastoris mutants in six different genes that are defective in autophagic peroxisome degradation in response to glucose. Four of these PDG genes were isolated, and DNA sequencing results indicate that all four encode novel proteins of unknown function. The specific aims of this continuing FIRCA proposal are: (1) to characterize the four PDG proteins by determining their subcellular location and searching for other genes whose products interact with them; (2) to determine what other vacuolar sorting pathways are affected by mutations in each gene; and (3) to develop and utilize novel screens and selection methods for the isolation of mutants in new PDG genes. Results of these studies will provide important insights into autophagic mechanisms.