Cell cycle-regulated nuclear localization of MCM2 and MCM3, which are required for the initiation of DNA synthesis at chromosomal replication origins in yeast.
Cell cycle-regulated nuclear localization of MCM2 and MCM3, which are required for the initiation of DNA synthesis at chromosomal replication origins in yeast.
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DOI：
10.1101/gad.7.11.2149
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发表时间：
1993-11
影响因子：
10.5
通讯作者：
Hong Yan;Ankit Margaret Merchant;B. Tye
中科院分区：
文献类型：
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作者：
Hong Yan;Ankit Margaret Merchant;B. Tye
MCM2和MCM3是酿酒酵母中两种遗传相互作用且结构相关的蛋白质，对生长至关重要。这些蛋白质的突变缺陷通常会影响微型染色体的稳定性，但缺陷的严重程度取决于驱动该质粒复制的自主复制序列（ARS）。在本文中，我们表明，通过二维凝胶电泳，在染色体复制起点的DNA合成的起始频率也降低了这些突变体。我们进一步表明，核和亚核定位的MCM2和MCM3蛋白质的时间调节相对于细胞周期。这些蛋白质在有丝分裂结束时进入细胞核，在整个G1期持续存在，并在S期开始时从细胞核中消失。一旦进入细胞核，一部分MCM2和MCM3蛋白就会与DNA紧密结合。MCM2和MCM3与染色质的结合可能导致DNA合成的启动，并且它们随后从细胞核中的消失可能阻止复制起点处DNA合成的重新启动。MCM2和MCM3在细胞核中的这种时间和空间限制性定位可以用于确保DNA复制在每个细胞周期发生一次且仅发生一次。
MCM2 and MCM3 are two genetically interacting and structurally related proteins essential for growth in Saccharomyces cerevisiae. Mutants defective in these proteins affect the stability of minichromosomes in general, but the severity of the defect is dependent on the autonomously replicating sequence (ARS) that drives the replication of that plasmid. In this paper we show by two-dimensional gel electrophoresis that the initiation of DNA synthesis at chromosomal replication origins is also reduced in frequency in these mutants. We show further that the nuclear and subnuclear localizations of the MCM2 and MCM3 proteins are temporally regulated with respect to the cell cycle. These proteins enter the nucleus at the end of mitosis, persist there throughout G1 phase, and disappear from it at the beginning of S phase. Once inside the nucleus, a fraction of the MCM2 and MCM3 proteins becomes tightly associated with DNA. The association of MCM2 and MCM3 with chromatin presumably leads to the initiation of DNA synthesis, and their subsequent disappearance from the nucleus presumably prevents reinitiation of DNA synthesis at replication origins. This temporally and spatially restricted localization of MCM2 and MCM3 in the nucleus may serve to ensure that DNA replication occurs once and only once per cell cycle.