Slx1-Slx4 are subunits of a structure-specific endonuclease that maintains ribosomal DNA in fission yeast
Slx1-Slx4 are subunits of a structure-specific endonuclease that maintains ribosomal DNA in fission yeast
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DOI：
10.1091/mbc.e03-08-0586
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发表时间：
2004-01-01
影响因子：
3.3
通讯作者：
Russell, P
中科院分区：
文献类型：
--
作者：
Coulon, S;Gaillard, PHL;Russell, P
在大多数真核生物中，编码核糖体RNA（rDNA）的基因以长串联头-尾重复序列聚集。对酿酒酵母的研究表明，rDNA拷贝数是通过与复制叉（RF）的位点特异性阻断相关的重组事件来维持的。在这里，我们描述了两个裂殖酵母蛋白，同源的S。酿酒酵母Slx 1和Slx 4，作为维持rDNA拷贝数的新型内切核酸酶的亚基。Slx 1-Slx 4依赖性核酸内切酶在双链体DNA中与单链DNA连接的3'侧上引入单链切割。Slx 1或Rqh 1 RecQ样DNA解旋酶的缺失引起rDNA收缩，而同时消除Slx 1-Slx 4核酸内切酶和Rqh 1是致命的。Slx 1与染色质结合在两个区域，这两个区域是S.粟酒我们提出了一个模型，其中的Slx 1-Slx 4复杂的参与控制的扩展和收缩的rDNA位点启动重组事件在停滞的RF。
In most eukaryotes, genes encoding ribosomal RNAs (rDNA) are clustered in long tandem head-to-tail repeats. Studies of Saccharomyces cerevisiae have indicated that rDNA copy number is maintained through recombination events associated with site-specific blockage of replication forks (RFs). Here, we describe two Schizosaccharomyces pombe proteins, homologs of S. cerevisiae Slx1 and Slx4, as subunits of a novel type of endonuclease that maintains rDNA copy number. The Slx1-Slx4-dependent endonuclease introduces single-strand cuts in duplex DNA on the 3' side of junctions with single-strand DNA. Deletion of Slx1 or Rqh1 RecQ-like DNA helicase provokes rDNA contraction, whereas simultaneous elimination of Slx1-Slx4 endonuclease and Rqh1 is lethal. Slx1 associates with chromatin at two foci characteristic of the two rDNA repeat loci in S. pombe. We propose a model in which the Slx1-Slx4 complex is involved in the control of the expansion and contraction of the rDNA loci by initiating recombination events at stalled RFs.