Tanaka T, Knapp D, Nasmyth K
Research Institute of Molecular Pathology, Vienna, Austria.
Cell. 1997 Aug 22;90(4):649-60. doi: 10.1016/s0092-8674(00)80526-7.
In eukaryotic cells, firing of DNA replication origins normally does not recur until after M phase. This characteristic is thought to be due to the properties of "initiation" proteins like Orc, Cdc6, and Mcms. Using formaldehyde cross-linking, we show that Cdc6p and Mcm7p associate specifically with replication origins during G1 but not during G2 in S. cerevisiae. Mcm7p's association with origins depends on Cdc6p. Ectopic expression of Cdc6p enables it to associate with origins during G2, but this fails to recruit Mcm7p. Our data suggest that the loading of Mcm proteins onto origins is regulated by two mechanisms: first, by Cdc6p occupancy, and second, by S- and M-CDKs, whose activity during S, G2, and M phases prevents Mcm loading.
在真核细胞中，DNA复制起点的激发通常直到M期之后才会再次发生。这种特性被认为是由于诸如Orc、Cdc6和Mcm等“起始”蛋白的特性所致。使用甲醛交联，我们发现Cdc6p和Mcm7p在酿酒酵母的G1期而非G2期与复制起点特异性结合。Mcm7p与起点的结合依赖于Cdc6p。Cdc6p的异位表达使其能够在G2期与起点结合，但这无法招募Mcm7p。我们的数据表明，Mcm蛋白加载到起点受到两种机制的调控：第一，通过Cdc6p的占据；第二，通过S期和M期周期蛋白依赖性激酶（S-和M-CDKs），其在S期、G2期和M期的活性会阻止Mcm加载。
