The First Green Lineage cdc25 Dual-Specificity Phosphatase.

The Cdc25 protein phosphatase is a key enzyme involved in the regulation of the G(2)/M transition in metazoans and yeast. However, no Cdc25 ortholog has so far been identified in plants, although functional studies have shown that an activating dephosphorylation of the CDK-cyclin complex regulates the G(2)/M transition. In this paper, the first green lineage Cdc25 ortholog is described in the unicellular alga Ostreococcus tauri. It encodes a protein which is able to rescue the yeast S. pombe cdc25-22 conditional mutant. Furthermore, microinjection of GST-tagged O. tauri Cdc25 specifically activates prophase-arrested starfish oocytes. In vitro histone H1 kinase assays and anti-phosphotyrosine Western Blotting confirmed the in vivo activating dephosphorylation of starfish CDK1-cyclinB by recombinant O. tauri Cdc25. We propose that there has been coevolution of the regulatory proteins involved in the control of M-phase entry in the metazoan, yeast and green lineages.

Khadaroo, B., Robbens, S., Ferraz, C., Derelle, E., Eychenie, S., Cooke, R., Peaucellier, G., Delseny, M., Demaille, J., Van de Peer, Y., Picard, A. (2004) The First Green Lineage cdc25 Dual-Specificity Phosphatase. Cell Cycle 3(4):513-8.









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