tailieunhanh - Báo cáo Y học: Rum1, an inhibitor of cyclin-dependent kinase in fission yeast, is negatively regulated by mitogen-activated protein kinase-mediated phosphorylation at Ser and Thr residues

The p25rum1 is an inhibitor of Cdc2 kinase expressed in fission yeast and plays an important role in cell-cycle control. As its amino-acid sequence suggests that p25rum1 has putative phosphorylation sites for mitogen-activated protein kinase (MAPK), we investigated the ability of MAPK to phosphorylate p25rum1. Direct in vitro kinase assay using GST-fusion proteins of wild-type as well as various mutants of p25rum1 demonstrated that MAPK phosphorylates the N-terminal portion of p25rum1 and residues Thr13 and Ser19 are major phosphorylation sites for MAPK | Eur. J. Biochem. 269 3511-3521 2002 FEBS 2002 doi Rumi an inhibitor of cyclin-dependent kinase in fission yeast is negatively regulated by mitogen-activated protein kinase-mediated phosphorylation at Ser and Thr residues Kentaro Matsuoka1 2. Nobutaka Kivokawa1 Tomoko Taguchi1. Jun Matsui1 Tovo Suzuki1 Kenichi Mimori1. Hideki Nakajima1 Hisami Takenouchi1 Tang Weiran1 Yohko U. Katagiri1 and Junichiro Fujimoto1 1Department of Pathology National Children s Medical Research Center Tokyo Japan department of Pathology Keio University School of Medicine Tokyo Japan The p25rum1 is an inhibitor of Cdc2 kinase expressed in fission yeast and plays an important role in cell-cycle control. As its amino-acid sequence suggests that p25rum1 has putative phosphorylation sites for mitogen-activated protein kinase MAPK we investigated the ability of MAPK to phosphorylate p25rum1. Direct in vitro kinase assay using GST-fusion proteins of wild-type as well as various mutants of p25rum1 demonstrated that MAPK phosphorylates the N-terminal portion of p25rum1 and residues Thr13 and Ser19 are major phosphorylation sites for MAPK. In addition phosphorylation of p25rum1 by MAPK revealed markedly reduced Cdc2 kinase inhibitor ability of the protein. Together with the fact that replacement of both Thr13 and Ser19 with Glu which mimics the phosphorylated state of these residues also significantly reduces the activity of p25rum1 as a Cdc2 inhibitor it was suggested that the phosphorylation of Thr13 and Ser19 negatively regulates the function of p25rum1. Further evidence indicates that phosphorylation of Thr13 and Ser19 may retain a negative effect on the function of p25rum1 even in vivo. Therefore MAPK may regulate the function of p25rum1 via phosphorylation of its Thr and Ser residues and thus participate in cell cycle control in fission yeast. Keywords cell cycle Rum1 Cdc2 mitogen-activated protein kinase phosphorylation. The yeasts have been the favored .