Mutations in a partitioning protein and altered chromatin structure at the partitioning locus prevent cohesin recruitment by the Saccharomyces cerevisiae plasmid and cause plasmid missegregation.
Mutations in a partitioning protein and altered chromatin structure at the partitioning locus prevent cohesin recruitment by the Saccharomyces cerevisiae plasmid and cause plasmid missegregation.
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分区蛋白的突变和分区位点染色质结构的改变会阻止酿酒酵母质粒招募粘连蛋白，并导致质粒错误分离。
DOI：
10.1128/mcb.24.12.5290-5303.2004
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Velmurugan,Soundarapandian
中科院分区：
文献类型：
--
作者：
Yang,Xian-Mei;Mehta,Shwetal;Uzri,Dina;Jayaram,Makkuni;Velmurugan,Soundarapandian
2μm圆环是存在于酵母细胞核中的一个高度持久的“自私”DNA元件，其稳定性接近染色体。质粒分配系统，由两个质粒编码的蛋白质，Rep 1 p和Rep 2 p，和酸作用位点，STB，显然饲料到染色体分离途径。Rep蛋白在S期协助酵母粘附素复合物向STB的募集，推测是为了将复制的质粒分子均等地分配给子细胞。分配系统的DNA-蛋白质和蛋白质-蛋白质相互作用，以及染色质在STB的组织，对于粘附素的募集是重要的。不能与Rep 2 p、STB或两者结合的Rep 1 p变体不能辅助粘附素复合物atSTBand的组装，在质粒维持中是无功能的。在不阻碍Rep 1 p-Rep 2 p-STB相互作用的情况下阻止粘附素-STB缔合也会导致质粒错误分离。在酵母细胞周期中，Rep 1 p和Rep 2 p蛋白在G1期晚期和S期早期之间的短时间间隔内从STB中排出。这种解离和再结合事件确保了粘附素在STB上的加载是复制依赖性的，并且与染色体粘附素的募集相协调。在anrsc 2 Δ酵母菌株中，由于缺乏特异性染色质重塑复合物并表现出高度的质粒丢失，Rep 1 p和粘附素复合物都不能被募集到STB。Rep 1 p突变和thersc 2 Δ突变的表型与粘附素在质粒分配中的作用类似于在染色体分配中的作用一致。
The 2μm circle is a highly persistent “selfish” DNA element resident in theSaccharomyces cerevisiaenucleus whose stability approaches that of the chromosomes. The plasmid partitioning system, consisting of two plasmid-encoded proteins, Rep1p and Rep2p, and acis-acting locus,STB, apparently feeds into the chromosome segregation pathway. The Rep proteins assist the recruitment of the yeast cohesin complex toSTBduring the S phase, presumably to apportion the replicated plasmid molecules equally to daughter cells. The DNA-protein and protein-protein interactions of the partitioning system, as well as the chromatin organization atSTB, are important for cohesin recruitment. Rep1p variants that are incompetent in binding to Rep2p,STB, or both fail to assist the assembly of the cohesin complex atSTBand are nonfunctional in plasmid maintenance. Preventing the cohesin-STBassociation without impeding Rep1p-Rep2p-STBinteractions also causes plasmid missegregation. During the yeast cell cycle, the Rep1p and Rep2p proteins are expelled fromSTBduring a short interval between the late G1and early S phases. This dissociation and reassociation event ensures that cohesin loading atSTBis replication dependent and is coordinated with chromosomal cohesin recruitment. In anrsc2Δ yeast strain lacking a specific chromatin remodeling complex and exhibiting a high degree of plasmid loss, neither Rep1p nor the cohesin complex can be recruited toSTB. The phenotypes of the Rep1p mutations and of thersc2Δ mutant are consistent with the role of cohesin in plasmid partitioning being analogous to that in chromosome partitioning.