ORC and the intra-S-phase checkpoint: a threshold regulates Rad53p activation in S phase
ORC and the intra-S-phase checkpoint: a threshold regulates Rad53p activation in S phase
复制标题
DOI：
10.1101/gad.239802
复制
发表时间：
2002-12-15
影响因子：
10.5
通讯作者：
Gasser, SM
中科院分区：
文献类型：
--
作者：
Shimada, K;Pasero, P;Gasser, SM
酵母中的 S 相内检查点通过激活 ATM 样激酶 Mec1 和 CHK2 相关激酶 Rad53 对停滞的复制叉做出反应，这反过来又抑制纺锤体伸长和晚期起源激发，并导致停滞的复制叉处的 DNA 聚合酶稳定。一种突变会破坏起源识别复合物 orc2-1 的第二个亚基的稳定性，使功能性复制叉的数量减少 30%，并因复制应激或 S 期 DNA 损伤而严重损害 Rad53 的激活。我们发现检查点反应的恢复与 G1 期复制前复合物形成的恢复以剂量依赖性方式相关。其他形式的 DNA 损伤可以补偿 orc2-1 突变体中叉依赖性信号水平的降低，但即使在野生型细胞中，S 期 Rad53 激活所需的损伤量也高于 G2 期。我们的数据表明，存在 S 期特异性阈值，这可能是细胞耐受正常复制叉上存在的损伤样 DNA 结构所必需的。
The intra-S-phase checkpoint in yeast responds to stalled replication forks by activating the ATM-like kinase Mec1 and the CHK2-related kinase Rad53, which in turn inhibit spindle elongation and late origin firing and lead to a stabilization of DNA polymerases at arrested forks. A mutation that destabilizes the second subunit of the Origin Recognition Complex, orc2-1, reduces the number of functional replication forks by 30% and severely compromises the activation of Rad53 by replication stress or DNA damage in S phase. We show that the restoration of the checkpoint response correlates in a dose-dependent manner with the restoration of pre-replication complex formation in G1. Other forms of DNA damage can compensate for the reduced level of fork-dependent signal in the orc2-1 mutant, yet even in wild-type cells, the amount of damage required for Rad53 activation is higher in S phase than in G2. Our data suggest the existence of an S-phase-specific threshold that may be necessary to allow cells to tolerate damage-like DNA structures present at normal replication forks.