LEUCINE-ZIPPER TYPE TRANSCRIPTION FACTORS OF WHEAT

Sequence specific DNA-binding proteins play a significant role in transcriptional regulation. Wheat DNA-binding proteins, HBP-1a and HBP-1b, bind to the hexamer sequence of wheat histone gene promoters. Structural analyses of cDNAs encoding these proteins show that they belong to a leucine zipper class of transcription factors. They form homodimers but do not heterodimers between them. Although the hexamer sequence or its homologues exist in several plant genes, HBP-1a and -1b exhibited the highest binding affinity to the hexamer sequence in the histone gene promoters, suggesting that both DNA-binding proteins are involved in transcriptional regulation of wheat histone genes.