Isolation and characterization of cDNA clones encodingcdc2 homologues fromOryza sativa: a functional homologue and cognate variants

Abstract

Using probes obtained by PCR amplification, we have isolated two cognate rice cDNAs (cdc2Os-1 and cdc2Os-2) encoding structural homologues of the cdc2+/CDC28 (cdc2) protein kinase from a cDNA library prepared from cultured rice cells. Comparison of the deduced amino acid sequences of cdc2Os-1 and cdc2Os-2 showed that they are 83% identical. They are 62% identical to CDC28 of Saccharomyces cerevisiae and much more similar to the yeast and mammalian p34cdc2 kinases than to rice R2, a cdc2-related kinase isolated previously by screening the same rice cDNA library with a different oligonucleotide probe. Southern blot analysis indicated that the three rice clones (cdc2Os-1, cdc2Os-2 and R2) are derived from distinct genes and are each found in a single copy per rice haploid genome. RNA blot analysis revealed that these genes are expressed in proliferating rice cells and in young rice seedlings. cdc2Os-1 could complement a temperature-sensitive yeast mutant of cdc28. However, despite the similarity in structure, both cdc2Os-2 and R2 were unable to complement the same mutant. Thus, the present results demonstrate the presence of structurally related, but functionally distinct cognates of the cdc2 cell cycle kinase in rice.

Gibberellin promotes histone H1 kinase activity and the expression of cdc2 and cyclin genes during the induction of rapid growth in deepwater rice internodes

“…This homolog, cdc2Os-2, cannot rescue a yeast mutant arrested in the cell cycle (Hashimoto et al, 1992). Expression of cdc2Os-1, which is a functional homolog of the yeast gene, was not regulated by GA.…”

“…Both genes are expressed in cultured, proliferating cells, but only cdc2Os-1 can complement a temperature-sensitive CDC28 mutant of Saccharomyces cerevisiae that is blocked at the late G1 phase. This indicates different functions for the products of these two genes in regulating the cell cycle in rice (Hashimoto et al, 1992). cDNA clones encoding plant cyclin homologs have been isolated from carrot and soybean (Hata et al, 1991), Arabidopsis (Hemerly et al, 1992), alfalfa (Hirt et al, 1992) and maize (Renaudin et al, 1994).…”

Cell Cycle Phase Specificity of Putative Cyclin-Dependent Kinase Variants in Synchronized Alfalfa Cells

“…Highly homologous cdc2 gene pairs (exhibiting 80 to 90% amino acid identities) have been identified from several plant species, including maize, rice, alfalfa, soybean, Antirrhinum, and pea (Colasanti et al, 1991;Hashimoto et al, 1992;Hirt et al, 1993;Mia0 et al, 1993;Fobert et al, 1994;Jacobs 1995). The two alfalfa (Medicago sativa) cdc2 homologous genes (designated cdc2MsA and cdc2MsB) display different abilities to complement yeast cdc28 mutants blocked at GI-to-S and G,-to-M phases.…”

Cloning, expression, and characterization of cDNAs encoding Arabidopsis thaliana squalene synthase.

“…This strategy was successful for isolating theArabidopsis 3-hydroxy-3-methylglutaryl-CoA reductase gene (21,22). The mouse squalene synthase cDNA (11) was used as a probe, because we had found that plant cell-cycle-related genes were more similar to mammalian homologs than to yeast homologs (23)(24)(25)(26).…”