Yeast plasmid segregation: investigation of host/plasmid interactions

这个2µm的圆环是一个高拷贝数的质粒，稳定地存在于大多数烘焙酵母（Saccharomyces cerevisiae）的细胞核中。2µm的圆圈是一个“自私的”DNA，它借用宿主的机制进行复制和分离，以确保它在宿主细胞分裂时很少丢失，同时不给宿主带来任何好处。我们已经确定了sumoylation（用一个小的泛素相关蛋白SUMO修饰靶蛋白）作为调节质粒分离的宿主功能。生化、分子遗传学和细胞生物学方法将用于阐明summoylation和质粒维持之间的联系，并鉴定和研究质粒借用的其他宿主蛋白，使其能够遗传。荧光显微镜将用于研究在我们的研究中发现的宿主蛋白缺失对细胞分裂时多个质粒拷贝的均匀分配和质粒在细胞核内定位的影响。我们的研究也将有助于确定所鉴定的宿主蛋白所参与的细胞过程，并揭示其他蛋白质的新功能。该项目将确定2微米圆如何与原子核的其他组分相互作用，以确保其有效分离。了解酵母质粒如何利用summoylation和其他宿主过程可能揭示其他遗传元件（如病毒）是如何维持的，并有助于确定summoylation在细胞分裂过程中染色体忠实分离中的重要作用。

The 2µm circle is a high copy-number plasmid stably maintained in the nucleus of most strains of the bakers yeast, Saccharomyces cerevisiae. The 2µm circle is a "selfish" DNA, borrowing host machinery for its replication and segregation to ensure it is seldom lost when the host cell divides, while conferring no advantage to the host. We have identified sumoylation (modification of target proteins with a small ubiquitin-related protein called SUMO) as a host function that regulates plasmid segregation. Biochemical, molecular genetics, and cell biology approaches will be used to elucidate the link between sumoylation and plasmid maintenance and to identify and investigate other host proteins borrowed by the plasmid that enable its inheritance. Fluorescence microscopy will be used to investigate the effect of absence of host proteins identified in our studies on equal partitioning of the multiple plasmid copies at cell division and on plasmid localization within the nucleus. Our studies will also help identify the cellular process to which the identified host proteins contribute and reveal new functions for others. This project will determine how the 2µm circle interacts with other components of the nucleus to ensure its efficient segregation. Understanding how sumoylation and other host processes are exploited by the yeast plasmid may reveal how other genetic elements, such as viruses are maintained and help determine the essential role sumoylation plays in faithful segregation of chromosomes during cell division.