动态蛋白质磷酸化构成了所有生物体中的基本调节机制。磷蛋白磷酸酶4(PP4)是一种保守且必需的细胞核丝氨酸和苏氨酸磷酸酶。尽管PP4的重要性,底物选择的一般原则是未知的,阻碍了这种磷酸酶对信号调节的研究。这里,我们确定并彻底表征了一般的PP4共有结合基序,FxxP主题.X射线晶体学研究表明,FxxP基序与PP4调节亚基PPP4R3中的保守口袋结合。与PP4相互作用蛋白的蛋白质组学分析相结合的全系统计算机搜索使我们能够识别控制一系列基本细胞过程的蛋白质中的许多FxxP基序。我们在粘附蛋白释放因子WAPL中鉴定了FxxP基序,并表明这调节了WAPL的磷酸化状态,并且是有效释放粘附蛋白所必需的。总的来说,我们的工作揭示了PP4特异性的基本原理,对理解细胞中磷酸化介导的信号传导具有广泛的意义。
Dynamic protein phosphorylation constitutes a fundamental regulatory mechanism in all organisms. Phosphoprotein phosphatase 4 (PP4) is a conserved and essential nuclear serine and threonine phosphatase. Despite the importance of PP4, general principles of substrate selection are unknown, hampering the study of signal regulation by this phosphatase. Here, we identify and thoroughly characterize a general PP4
consensus-binding motif, the FxxP motif. X-ray crystallography studies reveal that FxxP motifs bind to a conserved pocket in the PP4 regulatory subunit PPP4R3. Systems-wide in silico searches integrated with proteomic analysis of PP4 interacting proteins allow us to identify numerous FxxP motifs in proteins controlling a range of fundamental cellular processes. We identify an FxxP motif in the
cohesin release factor WAPL and show that this regulates WAPL phosphorylation status and is required for efficient
cohesin release. Collectively our work uncovers basic principles of PP4 specificity with broad implications for understanding phosphorylation-mediated signaling in cells.