Bass Thomas E, Luzwick Jessica W, Kavanaugh Gina, Carroll Clinton, Dungrawala Huzefa, Glick Gloria G, Feldkamp Michael D, Putney Reid, Chazin Walter J, Cortez David
Department of Biochemistry, Vanderbilt University School of Medicine, 613 Light Hall, 2215 Garland Avenue, Nashville, Tennessee 37232, USA.
Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, USA.
Nat Cell Biol. 2016 Nov;18(11):1185-1195. doi: 10.1038/ncb3415. Epub 2016 Oct 10.
The ATR checkpoint kinase coordinates cellular responses to DNA replication stress. Budding yeast contain three activators of Mec1 (the ATR orthologue); however, only TOPBP1 is known to activate ATR in vertebrates. We identified ETAA1 as a replication stress response protein in two proteomic screens. ETAA1-deficient cells accumulate double-strand breaks, sister chromatid exchanges, and other hallmarks of genome instability. They are also hypersensitive to replication stress and have increased frequencies of replication fork collapse. ETAA1 contains two RPA-interaction motifs that localize ETAA1 to stalled replication forks. It also interacts with several DNA damage response proteins including the BLM/TOP3α/RMI1/RMI2 and ATR/ATRIP complexes. It binds ATR/ATRIP directly using a motif with sequence similarity to the TOPBP1 ATR-activation domain; and like TOPBP1, ETAA1 acts as a direct ATR activator. ETAA1 functions in parallel to the TOPBP1/RAD9/HUS1/RAD1 pathway to regulate ATR and maintain genome stability. Thus, vertebrate cells contain at least two ATR-activating proteins.
ATR 检查点激酶协调细胞对 DNA 复制应激的反应。芽殖酵母含有三种 Mec1（ATR 的同源物）激活剂；然而，在脊椎动物中已知只有 TOPBP1 能激活 ATR。我们在两项蛋白质组学筛选中鉴定出 ETAA1 是一种复制应激反应蛋白。缺乏 ETAA1 的细胞会积累双链断裂、姐妹染色单体交换以及基因组不稳定的其他特征。它们对复制应激也高度敏感，并且复制叉崩溃的频率增加。ETAA1 包含两个 RPA 相互作用基序，可将 ETAA1 定位到停滞的复制叉上。它还与几种 DNA 损伤反应蛋白相互作用，包括 BLM/TOP3α/RMI1/RMI2 和 ATR/ATRIP 复合物。它使用一个与 TOPBP1 ATR 激活域具有序列相似性的基序直接结合 ATR/ATRIP；并且与 TOPBP1 一样，ETAA1 作为直接的 ATR 激活剂发挥作用。ETAA1 与 TOPBP1/RAD9/HUS1/RAD1 途径并行发挥作用，以调节 ATR 并维持基因组稳定性。因此，脊椎动物细胞至少含有两种 ATR 激活蛋白。
