Characterization of wheat DP, a heterodimerization partner of the plant E2F transcription factor which stimulates E2F-DNA binding.

Recent studies suggest that the G1/S transition in plants depends on the activity of E2F transcription factors. In animal cells, E2Fs interact with DP proteins, whose identification in plants has been elusive, so far. Here we show that although an E2F-containing DNA-binding activity can be detected in plant cell extracts, purified E2F protein binds poorly to DNA. In a yeast two-hybrid screening, using wheat E2F as a bait, we have isolated a cDNA clone encoding a wheat DP (TmDP) protein. TmDP is expressed ubiquitously and exhibits a domain organization similar to animal DPs. Contrary to the specificity observed for the plant RBR/E2F interaction, human and plant E2F and DP proteins can interact in a heterologous manner. Purified TmDP protein stimulates E2F-DNA complex formation.