Williams R Scott, Bernstein Nina, Lee Megan S, Rakovszky Melissa L, Cui Diana, Green Ruth, Weinfeld Michael, Glover J N Mark
Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.
Biochem Cell Biol. 2005 Dec;83(6):721-7. doi: 10.1139/o05-153.
The response of eukaryotic cells to DNA damage requires a multitude of protein-protein interactions that mediate the ordered repair of the damage and the arrest of the cell cycle until repair is complete. Two conserved protein modules, BRCT and forkhead-associated (FHA) domains, play key roles in the DNA-damage response as recognition elements for nuclear Ser/Thr phosphorylation induced by DNA-damage-responsive kinases. BRCT domains, first identified at the C-terminus of BRCA1, often occur as multiple tandem repeats of individual BRCT modules. Our recent structural and functional work has revealed how BRCT repeats recognize phosphoserine protein targets. It has also revealed a secondary binding pocket at the interface between tandem repeats, which recognizes the amino-acid 3 residues C-terminal to the phosphoserine. We have also studied the molecular function of the FHA domain of the DNA repair enzyme, polynucleotide kinase (PNK). This domain interacts with threonine-phosphorylated XRCC1 and XRCC4, proteins responsible for the recruitment of PNK to sites of DNA-strand-break repair. Our studies have revealed a flexible mode of recognition that allows PNK to interact with numerous negatively charged substrates.
真核细胞对DNA损伤的反应需要多种蛋白质-蛋白质相互作用，这些相互作用介导损伤的有序修复以及细胞周期的停滞，直到修复完成。两个保守的蛋白质模块，BRCT和叉头相关（FHA）结构域，在DNA损伤反应中作为DNA损伤反应激酶诱导的核丝氨酸/苏氨酸磷酸化的识别元件发挥关键作用。BRCT结构域最初在BRCA1的C末端被鉴定出来，通常以单个BRCT模块的多个串联重复形式出现。我们最近的结构和功能研究揭示了BRCT重复序列如何识别磷酸丝氨酸蛋白靶点。研究还揭示了串联重复序列之间界面处的一个二级结合口袋，该口袋识别磷酸丝氨酸C末端的3个氨基酸残基。我们还研究了DNA修复酶多核苷酸激酶（PNK）的FHA结构域的分子功能。该结构域与苏氨酸磷酸化的XRCC1和XRCC4相互作用，这两种蛋白质负责将PNK招募到DNA链断裂修复位点。我们的研究揭示了一种灵活的识别模式，使PNK能够与众多带负电荷的底物相互作用。
