Abstract
By using yeast two-hybrid screening, we identified a C3HC4-type ring domain containing protein which interacts with DREB2A and named D2AIP1. In Arabidopsis genome another two homologs were found and named D2AIP2 and D2AIP3. The three proteins were characterized to interact with DREB2A through the protein C-terminals. In vitro ubiquitination assays demonstrated that D2AIP1 ubiquitinates itself in the presence of ubiquitin, E1 and E2, and the C3HC4 ring domain was essential for its activity. Promoter activity analysis of D2AIP1 showed that it expresses in roots, cotyledons and flowers. DREB2A transcripts were also found in roots and cotyledons under normal condition, but the DREB2A protein could be hardly detected. When the transgenic plants harboring DREB2Apromoter:GFP-DREB2A were treated by a proteasome inhibitor MG132, a clear GFP inflorescence was observed. These results suggest that D2AIP1 interacts and ubiquitinates DREB2A under unstressed condition.
