抄録
We report that the Arabidopsis DREB2A Interacting Protein1 and 2 (DIP1 and DIP2), which are C3HC4 RING domain containing proteins identified from yeast two-hybrid screening, interact with the DREB2A protein in the nucleus. An in vitro ubiquitination assay showed that they function as E3 ubiquitin ligases and are capable of mediating DREB2A ubiquitination. Overexpression of DIP1 in Arabidopsis delayed the expression of DREB2A-regulated drought-responsive genes. Drought-inducible gene expression was slightly enhanced in the single T-DNA mutants of dip1-1 and dip2-1. In contrast, significantly enhanced gene expression was revealed in the dip1 dip2 mutant under dehydration stress. It implies that DIP1 and DIP2 function negatively in the response of plants to drought stress. Moreover, overexpression of full-length DREB2A protein was more stable in dip1-1 than in the wild-type background. These results suggest that DIP1 and DIP2 are novel negative regulators in drought-responsive gene expression by targeting DREB2A to 26S proteasome proteolysis.
