Abstract
DREB2A is an Arabidopsis transcription factor that expresses in response to water- and heat-stresses and contributes to acquisition of tolerance against these stresses via transcriptional activation of stress-specific target genes. DREB2A is considered to be inactivated under non-stressful conditions by its negative regulatory domain and activated in response to stress signals. However, signals that determin inactivation and activation of DREB2A are not clear.
DREB2B is a homolog of DREB2A that occurred through gene duplication in Brassicaceae. We have reported DRE-dependent transactivation activity and negative regulation of DREB2B is weaker than those of DREB2A. Several differences in amino acid sequences of the DNA-binding domain and the negative regulatory domain between DREB2A and DREB2B could result in the differences in the properties. To determine key amino acid residues responsible for the differences, we substituted these residues of DREB2A into corresponding residues of DREB2B, and compared the properties between mutant and wild-type proteins. We also report about analysis of transgenic Arabidopsis that express constitutive active forms of DREB2A and DREB2B.
