Role for a Xenopus Orc2-related protein in controlling DNA replication
Role for a Xenopus Orc2-related protein in controlling DNA replication
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DOI：
10.1038/379357a0
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发表时间：
1996-01-25
期刊：
影响因子：
64.8
通讯作者：
Dunphy, WG
中科院分区：
文献类型：
--
作者：
Carpenter, PB;Mueller, PR;Dunphy, WG
六亚基起源识别复合体（ORC）对于出芽酵母酵母在特定起点的DNA复制起始至关重要（1-9）。一个重要的问题是，在复制起源特征不明确的高等真核生物中，DNA复制是否通过orc依赖机制发生（10）。我们已经通过拯救分裂酵母Schizosaccharomyces pombe的有丝分裂突变体的能力鉴定了非洲爪蟾orc2相关蛋白（XORC2）。我们发现，非洲爪蟾卵提取物中的XORC2免疫缺失（11-13）会消除染色体DNA的复制，但不会消除单链DNA模板上的延伸合成。间接免疫荧光表明，XORC2在DNA合成开始之前就与染色质结合，甚至在阻止复制许可因子与DNA关联的条件下也是如此。这些发现表明，Orc2在动物细胞染色体复制的早期阶段起着重要作用。
THE six-subunit origin recognition complex (ORC) is essential for the initiation of DNA replication at specific origins in the budding yeast Saccharomyces cerevisiae(1-9). An important issue is whether DNA replication in higher eukaryotes, in which the characteristics of replication origins are poorly defined(10), occurs by an ORC-dependent mechanism, We have identified a Xenopus laevis Orc2-related protein (XORC2) by its ability to rescue a mitotic-catastrophe mutant of the fission yeast Schizosaccharomyces pombe, We show that immunodepletion of XORC2 from Xenopus egg extracts(11-13) abolishes the replication of chromosomal DNA but not elongation synthesis on a single-stranded DNA template, Indirect immunofluorescence indicates that XORC2 binds to chromatin well before the commencement of DNA synthesis, and even under conditions that prevent the association of replication licensing factor(s) with the DNA. These findings suggest that Orc2 plays an important role at an early step of chromosomal replication in animal cells.