Abstract
Arabidopsis DREB2A protein functions in both water and heat stress responses in plant. Recently, we demonstrated that DREB2A protein is modified by ubiquitination and subjected to 26S proteasome mediated proteolysis, which executes a negative regulation on the protein activity. Upon stress stimuli, a positive posttranscriptional modification is supposed to happen on the DREB2A protein for its activation. We carried out deletion and point mutagenesis analyses on DREB2A Negative Regulation Domain (NRD). A removal of 136 a.a. -150 a.a. from the DREB2A protein is sufficient to transform it into constitutive active. Among these fifteen amino acid residues, there are eight serine or threonine residues. However, it is likely that phosphorylation modification is less possible for DREB2A activation, since changing serine or threonine into either alanine or aspartic acid could enhance DREB2A transactivation activity. The O-linked N-actylglucosaminie (O-GlcNAc) modification is now in our consideration.
