Specificity of DNA sequences recognized by the zinc-finger homeodomain protein, GmZF-HD1 in soybean

Abstract Zinc finger-homeodomain proteins (ZF-HDs) have been identified in many plant species. In soybean ( Glycine max ), GmZF-HD1 functions as a transcription factor that activates the soybean calmodulin isoform-4 ( GmCaM-4 ) gene in response to pathogens. Recently, we reported specific binding of GmZF-HD1 to a 30-nt A/T-rich cis -element which constitutes two repeats of a conserved homeodomain binding site, ATTA, within −1207 to −1128 bp of the GmCaM-4 promoter. Herein, homeodomain sequences of the GmZF-HD1 protein were compared to those of other homeodomain proteins and characterized the specificity of DNA sequences in the interaction of the GmCaM-4 promoter with GmZF-HD1 protein. Considering the conservation of homeodomains in plants, the AG sequence within a 30-nt A/T-rich cis -element is required for binding of the GmZF-HD1 protein. Approximately 25-bp of A/T-rich DNA sequences containing an AG sequence is necessary for effective binding to the GmZF-HD1 protein. Taken together, the results support the notion that the GmZF-HD1 protein specifically functions in plant stress signalling by interacting with the promoter of GmCaM-4 .