Abstract：
The protein kinase ATR is essential for replication stress responses in all eukaryotes. Ribonucleotide reductase (RNR) catalyzes the formation of deoxyribonucleotide (dNTP), the universal building block for DNA replication and repair. However, the relationship between ATR and RNR is not well understood. Here, we show that ATR promotes the protein stability of RNR in Arabidopsis. Through an activation tagging-based genetic screen, we found that overexpression of TSO2, a small subunit of RNR, partially suppresses the hypersensitivity of the atr mutant to replication stress. Biochemically, TSO2 interacts with PRL1, a central subunit of the Cullin4-based E3 ubiquitin ligase CRL4PRL1, which polyubiquitinates TSO2 and promotes its degradation. ATR inhibits CRL4PRL1 to attenuate TSO2 degradation. Our work provides an important insight into the replication stress responses and a post-translational regulatory mechanism for RNR. Given the evolutionary conservation of the proteins involved, the ATR-PRL1-RNR module may act across eukaryotes.
摘要：
蛋白激酶ATR对于所有真核生物的复制应激反应至关重要。核糖核苷酸还原酶（RNR）催化脱氧核糖核苷酸（dNTP）的形成，DNA复制和修复的通用构件。然而,ATR和RNR之间的关系尚不清楚。这里,我们证明ATR促进拟南芥RNR的蛋白质稳定性。通过基于激活标记的遗传筛选，我们发现RNR的一个小亚基TSO2的过表达,部分抑制atr突变体对复制应激的超敏反应。生物化学,TSO2与PRL1相互作用，PRL1是基于Cullin4的E3泛素连接酶CRL4PRL1的中心亚基，其多泛素化TSO2并促进其降解。ATR抑制CRL4PRL1以减弱TSO2降解。我们的工作为RNR的复制应激反应和翻译后调控机制提供了重要的见解。考虑到相关蛋白质的进化保守性，ATR-PRL1-RNR模块可能在真核生物中起作用。
