REGULATION OF RETROTRANSPOSITION IN S CEREVISIAE

描述：酵母的Ty1元件是一种逆转录转座子，编码 结构蛋白、蛋白水解酶、整合酶和逆转录酶。 像逆转录病毒一样，这些产物是通过转录 多顺反子信息和翻译后处理事件，如 蛋白水解酶的切割和磷酸化。尽管Ty1 RNA代表一种 占细胞总RNA的很大一部分，转座事件很少见， 可能是由于一种称为转位的调节机制 休眠。 这项提案的主要目标是确定和描述 与换位休眠有关的细胞基因。这些基因是 通过导致过度转位表型的突变来鉴定的。这个 Pi使用了一种新的报告基因结构来筛选这种突变 目前已分离出160多个突变。最初的焦点 将对影响转位的这些因素的子集进行表征 在转录后水平而不是那些增加的突变 Ty1转录速率。突变体的基因特征将 包括互补测试、优势关系以及几个 进行基因和分子筛查，以确定 突变会影响转座过程。选定的基因将是 通过高转座表型的互补来克隆。台阶 在形成Ty1样颗粒的过程中，如蛋白酶激活(a 限速步骤)和VLP的形成将在突变体和野生- 对细胞进行分类以确定转位调控的新机制。

DESCRIPTION: The Ty1 elements of yeast are retrotransposons that encode structural proteins, protease, integrase, and reverse transcriptase. Like retroviruses, these products are formed by transcription of polycistronic messages and post-translational processing events such as protease cleavages and phosphorylation. Although Ty1 RNA represents a large fraction of total RNA in the cell, transposition events are rare, presumably due to a mechanism of regulation called transpositional dormancy. The main objective of this proposal is to identify and characterize the cellular genes involved in transpositional dormancy. These genes are identified by mutations that cause a hypertranspositional phenotype. The PI has used a novel reporter gene construct to screen for such mutations and at present over 160 mutations have been isolated. The initial focus will be on characterizing a subset of these which affect transposition at a post-transcriptional level rather than those mutations that increase Ty1 transcription rates. Genetic characterization of the mutants will include complementation test, dominance relationships, and several genetic and molecular screens to determine the level at which the mutation affects the transposition process. Selected genes will be cloned by complementation of the hypertranspositional phenotype. Steps in the formation of Ty1-like particles, such as protease activation (a rate-limiting step) and VLP formation will be studied in mutant and wild- type cells to identify new mechanisms of transpositional regulation.