title: Arabidopsis MAP kinase phosphatase 1 is phosphorylated and activated by its substrate AtMPK6.
abstract: Arabidopsis MAP kinase phosphatase 1 (AtMKP1) is a member of the mitogen-activated protein kinase (MPK) phosphatase family, which negatively regulates AtMPKs. We have previously shown that AtMKP1 is regulated by calmodulin (CaM). Here, we examined the phosphorylation of AtMKP1 by its substrate AtMPK6. Intriguingly, AtMKP1 was phosphorylated by AtMPK6, one of AtMKP1 substrates. Four phosphorylation sites were identified by phosphoamino acid analysis, TiO(2) chromatography and mass spectrometric analysis. Site-directed mutation of these residues in AtMKP1 abolished the phosphorylation by AtMPK6. In addition, AtMKP1 interacted with AtMPK6 as demonstrated by the yeast two-hybrid system. Finally, the phosphatase activity of AtMKP1 increased approximately twofold following phosphorylation by AtMPK6. By in-gel kinase assays, we showed that AtMKP1 could be rapidly phosphorylated by AtMPK6 in plants. Our results suggest that the catalytic activity of AtMKP1 in plants can be regulated not only by Ca(2+)/CaM, but also by its physiological substrate, AtMPK6.
authors: Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 660-701, Republic of Korea.
authors: Hyeong Cheol
authors: HC
authors: Park
authors: Eun Hyeon
authors: EH
authors: Song
authors: Xuan Canh
authors: XC
authors: Nguyen
authors: Kyunghee
authors: K
authors: Lee
authors: Kyung Eun
authors: KE
authors: Kim
authors: Ho Soo
authors: HS
authors: Kim
authors: Sang Min
authors: SM
authors: Lee
authors: Sun Ho
authors: SH
authors: Kim
authors: Dong Won
authors: DW
authors: Bae
authors: Dae-Jin
authors: DJ
authors: Yun
authors: Woo Sik
authors: WS
authors: Chung
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases; D017384:Sequence Deletion
chemical_list: D029681:Arabidopsis Proteins; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; C499612:MKP1 protein, Arabidopsis; D017027:Protein Tyrosine Phosphatases