The GA2 Locus of Arabidopsis thaliana Encodes ent-Kaurene Synthase of Gibberellin Biosynthesis

Journal Article

The ga2 mutant of Arabidopsis thaliana is a gibberellin-deficient dwarf. Previous biochemical studies have suggested that the ga2 mutant is impaired in the conversion of copalyl diphosphate to ent-kaurene, which is catalyzed by ent-kaurene synthase (KS). Over-expression of the previously isolated KS cDNA from pumpkin (Cu-curbita maxima) (CmKS) m the ga2 mutant was able to complement the mutant phenotype. A genomic clone coding for KS, AtKS, was isolated from A. thaliana using CmKS cDNA as a heterologous probe. The corresponding A. thaliana cDNA was isolated and expressed in Escherichia coli as a fusion protein. The fusion protein showed enzymatic activity that converted [3H]copalyl diphosphate to [3H]ent-kaurene. The recombinant AtKS protein derived from the ga2-1 mutant is truncated by 14 kD at the C-terminal end and does not contain significant KS activity in vitro. Sequence analysis revealed that a C-2099 to T base substitution, which converts Gln-678 codon to a stop codon, is present in the AtKS cDNA from the ga2-1 mutant. Taken together, our results show that the GA2 locus encodes KS.

Duke Authors

Cited Authors

  • Yamaguchi, S; Sun, T-P; Kawaide, H; Kamiya, Y

Published Date

  • January 1, 1998

Published In

  • Plant Physiology

Volume / Issue

  • 116 / 4

Start / End Page

  • 1271 - 1278

PubMed ID

  • 9536043