The Replication Initiation Protein Sld2 Regulates Helicase Assembly
The Replication Initiation Protein Sld2 Regulates Helicase Assembly
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DOI：
10.1074/jbc.m113.532085
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发表时间：
2014-01-24
影响因子：
4.8
通讯作者：
Kaplan, Daniel L.
中科院分区：
文献类型：
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作者：
Bruck, Irina;Kaplan, Daniel L.
必须调节 Cdc45-Mcm2-7-GINS (CMG) 复制解旋酶复合物的组装，以确保 DNA 解旋与 DNA 合成相结合。 Sld2 是芽殖酵母 DNA 复制启动所必需的。我们鉴定了 Sld2 的突变体 Sld2-m1,4，它在 Mcm2-7 结合方面存在特异性缺陷。当这种 sld2-m1,4 突变体表达时，细胞表现出 DNA 复制的严重抑制。此外，CMG 复合物在突变细胞中过早地在 G(1) 中组装，但在野生型细胞中则不然。这些数据表明，Sld2 与 Mcm2-7 的结合对于阻止 G(1) 中 CMG 解旋酶复合物的不当形成至关重要。我们还研究了 Sld2 的一种突变体，该突变体在结合 DNA 方面存在缺陷，即 sld2-DNA，并发现 sld2-DNA 细胞不表现出 GINS-Mcm2-7 相互作用。这些数据表明 Sld2 与 DNA 的结合是 S 期 CMG 组装所必需的。
Assembly of the Cdc45-Mcm2-7-GINS (CMG) replicative helicase complex must be regulated to ensure that DNA unwinding is coupled with DNA synthesis. Sld2 is required for the initiation of DNA replication in budding yeast. We identified a mutant of Sld2, Sld2-m1,4, that is specifically defective in Mcm2-7 binding. When this sld2-m1,4 mutant is expressed, cells exhibit severe inhibition of DNA replication. Furthermore, the CMG complex assembles prematurely in G(1) in mutant cells, but not wild-type cells. These data suggest that Sld2 binding to Mcm2-7 is essential to block the inappropriate formation of a CMG helicase complex in G(1). We also study a mutant of Sld2 that is defective in binding DNA, sld2-DNA, and find that sld2-DNA cells exhibit no GINS-Mcm2-7 interaction. These data suggest that Sld2 association with DNA is required for CMG assembly in S phase.