The function and regulation of budding yeast Swe1 in response to interrupted DNA synthesis
The function and regulation of budding yeast Swe1 in response to interrupted DNA synthesis
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DOI：
10.1091/mbc.e05-11-1093
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发表时间：
2006-06-01
影响因子：
3.3
通讯作者：
Wang, Yanchang
中科院分区：
文献类型：
--
作者：
Liu, Hong;Wang, Yanchang
DNA 合成和有丝分裂需要周期性调节的细胞周期蛋白依赖性激酶 (Cdk)。羟基脲 (HU) 通过消耗 dNTP（DNA 合成的基本单位）来抑制 DNA 合成。 HU 治疗会触发 S 期检查点，将细胞阻滞在 S 期，抑制晚期起源放电并稳定复制叉。使用芽殖酵母作为模型系统，我们发现 Swe1（Cdk 的负调节因子）出现在 S 期并在 HU 处理细胞中积累。有趣的是，这种积累并不依赖于 S 期检查点。 Delta hsl1、Delta hsl7 和 cdc5-2 突变体在 Swe1 降解方面存在缺陷，由于 Swe1 蛋白水平较高，因此表现出 HU 敏感性。我们进一步证明，他们的 HU 敏感性不是 DNA 损伤积累或 DNA 合成不完整的结果；相反，这种敏感性是由于它们从 HU 引起的 S 期停滞中恢复的时间大大延迟。引人注目的是，我们的体内数据表明 Swe1 抑制 Clb2-Cdk1 的激酶活性，但不抑制 Clb5-Cdk1 的激酶活性。因此，S 期积累的 Swe1 会阻止 Clb2-Cdk1 介导的有丝分裂活动，但对 Clb5-Cdk1 相关的 S 期进展几乎没有影响。
Periodically regulated cyclin-dependent kinase (Cdk) is required for DNA synthesis and mitosis. Hydroxyurea (HU) inhibits DNA synthesis by depleting dNTPs, the basic unit for DNA synthesis. HU treatment triggers the S-phase checkpoint, which arrests cells at S-phase, inhibits late origin firing and stabilizes replication forks. Using budding yeast as a model system, we found that Swe1, a negative regulator of Cdk, appears at S-phase and accumulates in HU treatment cells. Interestingly, this accumulation is not dependent on S-phase checkpoint. Delta hsl1, Delta hsl7, and cdc5-2 mutants, which have defects in Swe1 degradation, show HU sensitivity because of high Swe1 protein levels. We further demonstrated that their HU sensitivity is not a result of DNA damage accumulation or incomplete DNA synthesis; instead the sensitivity is due to their dramatically delayed recovery from HU-induced S-phase arrest. Strikingly, our in vivo data indicate that Swe1 inhibits the kinase activity of Clb2-Cdk1, but not that of Clb5-Cdk1. Therefore, S-phase accumulated Swe1 prevents Clb2-Cdk1-mediated mitotic activities, but has little effects on Clb5-Cdk1-associated S-phase progression.