A small CDC25 dual-specificity tyrosine-phosphatase isoform in Arabidopsis thaliana.
The dual-specificity CDC25 phosphatases are critical positive regulators of cyclin-dependent kinases (CDKs). Even though an antagonistic Arabidopsis thaliana WEE1 kinase has been cloned and tyrosine phosphorylation of its CDKs has been demonstrated, no valid candidate for a CDC25 protein has been reported in higher plants. We identify a CDC25-related protein (Arath;CDC25) of A. thaliana, constituted by a sole catalytic domain. The protein has a tyrosine-phosphatase activity and stimulates the kinase activity of Arabidopsis CDKs. Its tertiary structure was obtained by NMR spectroscopy and confirms that Arath;CDC25 belongs structurally to the classical CDC25 superfamily with a central five-stranded beta-sheet surrounded by helices. A particular feature of the protein, however, is the presence of an additional zinc-binding loop in the C-terminal part. NMR mapping studies revealed the interaction with phosphorylated peptidic models derived from the conserved CDK loop containing the phosphothreonine-14 and phosphotyrosine-15. We conclude that despite sequence divergence, Arath;CDC25 is structurally and functionally an isoform of the CDC25 superfamily, which is conserved in yeast and in plants, including Arabidopsis and rice.
Landrieu
Isabelle
I
Unité Mixte de Recherche 8525 Centre National de la Recherche Scientifique-Lille2, Institut de Biologie de Lille/Pasteur Institute of Lille, 59019 Lille Cedex, France. isabelle.landrieu@ibl.fr
da Costa
Marco
M
De Veylder
Lieven
L
Dewitte
Frédérique
F
Vandepoele
Klaas
K
Hassan
Sahar
S
Wieruszeski
Jean-Michel
JM
Corellou
Florence
F
Faure
Jean-Denis
JD
Van Montagu
Marc
M
Inzé
Dirk
D
Lippens
Guy
G
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001665:Binding Sites; D007527:Isoenzymes / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010766:Phosphorylation; D020687:cdc25 Phosphatases / Q000737:chemistry / Q000378:metabolism*
D029681:Arabidopsis Proteins; D007527:Isoenzymes; D020687:cdc25 Phosphatases