The Wip1 Phosphatase PPM1D Dephosphorylates SQ/TQ Motifs in Checkpoint Substrates Phosphorylated by PI3K-like Kinases

详细信息    查看全文

• 作者：Hiroshi Yamaguchi ; Stewart R. Durell ; Deb K. Chatterjee ; Carl W. Anderson ; Ettore Appella
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：November 6, 2007
• 年：2007
• 卷：46
• 期：44
• 页码：12594 - 12603
• 全文大小：317K
• 年卷期：v.46,no.44(November 6, 2007)
• ISSN：1520-4995

文摘

The wild-type p53-induced phosphatase Wip1 (PP2C or PPM1D) is a member of the proteinphosphatase 2C (PP2C) family and controls cell cycle checkpoints in response to DNA damage. p38MAPK and ATM were identified as physiological substrates of Wip1, and we previously reported a substratemotif that was defined using variants of the p38(180pT 182pY) diphosphorylated peptide, TDDEMpTGpYVAT. However, the substrate recognition motifs for Wip1 have not been fully defined as the sequencessurrounding the targeted residues in ATM and p38 MAPK appear to be unrelated. Using a recombinanthuman Wip1 catalytic domain (rWip1), in this study we measured the kinetic parameters for variants ofthe ATM(1981pS) phosphopeptide, AFEEGpSQSTTI. We found that rWip1 dephosphorylates phosphoserine and phosphothreonine in the p(S/T)Q motif, which is an essential requirement for substraterecognition. In addition, acidic, hydrophobic, or aromatic amino acids surrounding the p(S/T)Q sequencehave a positive influence, while basic amino acids have a negative influence on substrate dephosphorylation.The kinetic constants allow discrimination between true substrates and nonsubstrates of Wip1, and weidentified several new putative substrates that include HDM2, SMC1A, ATR, and Wip1 itself. A three-dimensional molecular model of Wip1 with a bound substrate peptide and site-directed mutagenesisanalyses suggested that the important residues for ATM(1981pS) substrate recognition are similar but notidentical to those for the p38(180pT 182pY) substrate. Results from this study should be useful for predictingnew physiological substrates that may be regulated by Wip1 and for developing selective anticancer drugs.