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First published online June 17, 2005; 10.1104/pp.105.059626 Plant Physiology 138:1627-1636 (2005) © 2005 American Society of Plant Biologists Atypical Regulation of a Green Lineage-Specific B-Type Cyclin-Dependent Kinase1Unité Mixte de Recherche 7628 Centre National de la Recherche Scientifique, Université Paris VI, Laboratoire Arago, Modèles en Biologie Cellulaire et Evolutive, BP44, 66651 Banyuls sur Mer, France
Cyclin-dependent kinases (CDKs) are the main regulators of cell cycle progression in eukaryotes. The role and regulation of canonical CDKs, such as the yeast (Saccharomyces cerevisiae) Cdc2 or plant CDKA, have been extensively characterized. However, the function of the plant-specific CDKB is not as well understood. Besides being involved in cell cycle control, Arabidopsis (Arabidopsis thaliana) CDKB would integrate developmental processes to cell cycle progression. We investigated the role of CDKB in Ostreococcus (Ostreococcus tauri), a unicellular green algae with a minimal set of cell cycle genes. In this primitive alga, at the basis of the green lineage, CDKB has integrated two levels of regulations: It is regulated by Tyr phosphorylation like cdc2/CDKA and at the level of synthesis-like B-type CDKs. Furthermore, Ostreococcus CDKB/cyclin B accounts for the main peak of mitotic activity, and CDKB is able to rescue a yeast cdc28ts mutant. By contrast, Ostreococcus CDKA is not regulated by Tyr phosphorylation, and it exhibits a low and steady-state activity from DNA replication to exit of mitosis. This suggests that from a major role in the control of mitosis in green algae, CDKB has evolved in higher plants to assume other functions outside the cell cycle.
1 This work was supported by the Centre National de la Recherche Scientifique (Young Investigator ATIP Fellowship to F.Y.B.). Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.059626. * Corresponding author; e-mail fy.bouget{at}obs-banyuls.fr; fax 33468887398. Received January 24, 2005; returned for revision April 4, 2005; accepted April 4, 2005. This article has been cited by other articles:
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