Molecular Cloning of cDNA for a Novel Pea Dof Protein, PsDof1, and Its DNA-Binding Activity to the Promoter of PsDof1 Gene

A cDNA clone, designated PsDof1, encoding a novel member of the Dof DNA-binding protein family was isolated from pea. Random-binding-site selection and gel retardation experiments showed that the GST-PsDof1 recombinant protein bound to specific DNA sequences with an AAAG core. A metal-chelating agent, 1, 10-phenanthroline, abolished binding of GST-PsDof1 to DNA, but the addition of Zn2+ restored it, indicating that zinc ions are required for its DNA-binding activity. Interestingly, there are possible sites for binding PsDof1 in its promoter sequence. Indeed, GST-PsDof1 binds to the AAAG-containing promoter sequence of the PsDof1 gene with higher affinity. These results suggest that PsDof1 is a novel transcription factor that is involved in its own transcriptional regulation.