Abstract
The eukaryotic cell cycle is controlled by cyclin-dependent kinases (CDKs). We previously found that Thr-161 residue of T-loop in tobacco CDKA was phosphorylated after reentry to the cell cycle. To investigate the role of the T-loop phosphorylation in tobacco CDKA, we generated tobacco BY-2 cells expressing estrogen-inducible GFP-fused CDKA protein in which Thr-161 residue was substituted to unphosphrylatable amino acid, alanine (T161A). As a control, BY-2 cells expressing GFP-fused CDKA (D146N) were generated. Consistent with previous studies, BY-2 cells expressing CDKA (D146N) caused dominant-negative effects and ceased cell division, but elongated . Although immunoprecipitates with GFP antibody prepared from BY-2 cells expressing CDKA (T161A) showed virtually no histone H1 kinase activity, neither reduction of CDKA kinase activity bound p13suc1 nor phenotypic change was observed. Further biochemical analysis is underway and will be presented and discussed.
