S. Jouannic et al., The protein kinases AtMAP3K epsilon 1 and BnMAP3K epsilon 1 are functionalhomologues of S. pombe cdc7p and may be involved in cell division, PLANT J, 26(6), 2001, pp. 637-649
We identified an Arabidopsis thaliana gene, AtMAP3K epsilon1, and a Brassic
a napus cDNA, BnMAP3K epsilon1, encoding functional protein serine/threonin
e kinases closely related to cdc7p and Cdc15p from Schizosaccharomyces pomb
e and Saccharomyces cerevisiae, respectively. This is the first report of c
dc7-related genes in non-fungal eukaryotes; no such genes have as yet been
identified in Metazoans. The B. napus protein is able to partially compleme
nt a cdc7 loss of function mutation in S. pombe. RT-PCR and in situ hybridi
sation revealed that the A. thaliana and B. napus genes are expressed in bo
th the sporophytic and the gametophytic tissues of the respective plant spe
cies and revealed further that expression is highest in dividing cells. Mor
eover, AtMAP3K epsilon1 gene expression is cell cycle-regulated, with highe
r expression in G2-M phases. Our results strongly suggest that the plant cd
c7p-related protein kinases are involved in a signal transduction pathway s
imilar to the SIN pathway, which positively regulates cytokinesis in S. pom
be.