Shimomura T, Ando S, Matsumoto K, Sugimoto K
Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-0814, Japan.
Mol Cell Biol. 1998 Sep;18(9):5485-91. doi: 10.1128/MCB.18.9.5485.
The RFC5 gene encodes a small subunit of replication factor C (RFC) complex in Saccharomyces cerevisiae and has been shown to be required for the checkpoints which respond to replication block and DNA damage. Here we describe the isolation of RAD24, known to play a role in the DNA damage checkpoint, as a dosage-dependent suppressor of rfc5-1. RAD24 overexpression suppresses the sensitivity of rfc5-1 cells to DNA-damaging agents and the defect in DNA damage-induced Rad53 phosphorylation. Rad24, like Rfc5, is required for the regulation of Rad53 phosphorylation in response to DNA damage. The Rad24 protein, which is structurally related to the RFC subunits, interacts physically with RFC subunits Rfc2 and Rfc5 and cosediments with Rfc5. Although the rad24Delta mutation alone does not cause a defect in the replication block checkpoint, it does enhance the defect in rfc5-1 mutants. Furthermore, overexpression of RAD24 suppresses the rfc5-1 defect in the replication block checkpoint. Taken together, our results demonstrate a physical and functional interaction between Rad24 and Rfc5 in the checkpoint pathways.
RFC5基因在酿酒酵母中编码复制因子C（RFC）复合体的一个小亚基，并且已被证明对于响应复制阻滞和DNA损伤的检查点是必需的。在此，我们描述了已知在DNA损伤检查点中起作用的RAD24作为rfc5-1的剂量依赖性抑制子的分离过程。RAD24的过表达抑制了rfc5-1细胞对DNA损伤剂的敏感性以及DNA损伤诱导的Rad53磷酸化缺陷。与Rfc5一样，Rad24也是响应DNA损伤调节Rad53磷酸化所必需的。Rad24蛋白在结构上与RFC亚基相关，它与RFC亚基Rfc2和Rfc5发生物理相互作用，并与Rfc5一起沉降。虽然单独的rad24Δ突变不会导致复制阻滞检查点出现缺陷，但它确实会增强rfc5-1突变体中的缺陷。此外，RAD24的过表达抑制了复制阻滞检查点中的rfc5-1缺陷。综上所述，我们的结果证明了Rad24和Rfc5在检查点途径中存在物理和功能上的相互作用。
