|Budget Amount *help
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Gibberellin 3-oxidase (GA3-ox) catalyzes final activation step in the biosynthesis of gibberellin, a plant hormone that regulates germination, elongation, flowering, and etc. GA3-ox belongs to the 2-oxoglutarate dependent-oxidase family, and C-terminal of GA3-ox includes catalytic center of this enzyme. On the other hand, function of the N-terminal of this enzyme has not been characterized yet, although it contains highly conserved motifs such as MWS/A/YEGY/FT. motif. In this study, the function of MWS/A/YEGY/FT motif in Arabidopsis GA3-ox, AtGA3oxl, was characterized by in vivo and in vitro experiments. The methionin or tryptophan residue in the motif was replaced with alanine to produce mutant proteins through preparation of mutant cDNA by PCR and its expression in E call. The mutant proteins prepared as fusion proteins in E. coli were incubated with gibberellin A_9 to examine their enzyme activities. Surprisingly, both mutant proteins showed equivalent activity with the normal protein indicating that MWS/A/YEGY/FT motif does not concern with catalytic activity of this enzyme. Therefore the mutant cDNA was introduced to Arabidopsis to examine its function by in vivo assay. As a result, T1 plants did not show any difference in their physiological appearance and expression level of GA-induced gene. Further analysis with T2 plants is necessary to confirm this result.