Copy number control of the yeast plasmid

酵母质粒2微米圈为自私基因组（或良性分子寄生虫）的进化提供了一个简单的实验范例。 这种DNA分子的遗传内容和组织致力于在群体中稳定地维持自身，而不会在细胞分裂时过度拉紧代谢机制质粒分子。 扩增系统也由质粒编码，如果质粒拷贝数由于分配偶尔失败而下降，则将质粒拷贝数调节回正常。 出于两个原因，放大系统必须被精细地调节。首先，它必须在稳态生长下被抑制，使得拷贝数的不受控制的增加不会对宿主构成威胁，并因此对质粒存活构成威胁。第二，一旦出现印数下降的情况，必须立即进行调试，使印数在短时间内恢复到正常值。 这个项目试图了解放大机制的两个方面。 首先，我们希望考虑可能的扩增模型，并通过使用适当设计的质粒底物来测试它们的预测。其次，我们希望分析什么样的生化步骤介导的Flp重组酶，扩增系统的中心组成部分，是重要的生产多个质粒拷贝从一个单一的复制起始事件。

The yeast plasmid 2 micron circle provides a simple experimental paradigm for the evolution of a selfish genome (or a benign molecular parasite). The genetic content and organization of this DNA molecule is devoted to maintaining itself stably in a population without unduly straining the metabolic machinery plasmid molecules at cell division. An amplification system, also encoded by the plasmid, adjusts plasmid copy number back to normal if and when it drops due to an occasional failure in partitioning. The amplification system must be exquisitely regulated for two reasons. First, it must be repressed under steady state growth, so that uncontrolled increase in copy number does not pose a threat to the host, and consequently to plasmid survival. Second, in the event of a fall in copy number, it must be commissioned immediately, so that copy number can be restored to the normal value within a short time. This project attempts to understand two aspects of the amplification mechanism. First, we wish to consider possible models for amplification, and test their predictions by using suitably designed plasmid substrates. Second we wish to analyze what biochemical steps mediated by the Flp recombinase, the central component of the amplification system, are important in the production of multiple plasmid copies from a single replication initiation event.