Functional analysis of Arabidopsis DREB2A protein, a transcription factor involved in dehydration- and high-salt response using a constitutive active form of the protein.

Abstract

DREB2A is a transcriptional factor that functions in drought- and high-salinity-responsive gene expression. This protein specifically binds to DRE/CRT in the promoter region of stress-inducible genes. However, only weak expression of putative target genes induced in transgenic Arabidopsis overexpressing DREB2A. Therefore, the post-translational modification such as phosphorylation seems to be necessary for activation of the DREB2A protein. To characterize activation mechanism of the DREB2A, we carried out domain analysis of the DREB2A protein using Arabidopsis T87 cell protoplasts. The analysis revealed that transcriptional activation domain existed in a region a.a. 253-335 and deletion of a.a. 135-165 or a.a. 318-335 of the DREB2A protein increased expression of a reporter gene. To identify target genes of the DREB2A, we performed microarrray analysis using Arabidopsis overexpressing a constitutive active form of DREB2A.