Association of the plant p34cdc2-like protein with p13suc1: implications for control of cell division cycles in plants

Abstract

Thecdc2-like p34 protein of wheat is closely similar to the p34cdc2 enzyme of yeasts and animals since both have binding affinity for p13suc1 protein encoded by the fission yeastsuc1 gene. In yeast p13suc1 participates in modulation of p34cdc2 activity and is necessary for completion of mitosis. Wheat p34 that was affinity purified on p13suc1 contained the PSTAIR amino acid sequence that is present in all known p34cdc2 homologues and it also had H1 histone protein kinase activity that was independent of calcium and cyclic AMP, which is characteristic of p34cdc2 in vitro. Functional equivalence with the known cell cycle control protein supports our earlier proposition that the high level of this homologue in wheat leaf meristem is important in determining where cell division can occur and the capacity for resumption of cell division. The affinity of plant p34 for fission yeast p13suc1 suggested that a similar association occurs in plants. We have detected a plant homologue of pl3suc1 using affinity-purified antibody raised against the fission yeast protein, in wheat, pea andChlamydomonas. We conclude that the distribution of p13suc1 homologue in plants is likely to be ubiquitous. Thesuc1 gene function inSchizosaccharomyces pombe is essential for mitosis, in which it is required for inactivation of p34cdc2. We propose that association of plant p34 with p13suc1 is similarly involved in plant mitosis.