Multiple Binding Motifs of RISBZ1, Seed Specific Transcription Factor

다국어 초록 (Multilingual Abstract)

The surveying of binding affinity between a particular transcription factor and DNA motifs is important in order to understand the developmental specific gene expression and regulatory networks of an organism. The microarray-based technologies (protein-binding microarrays; PBMs) provide useful predictions for understanding the transcriptional regulatory code in a genome-wide manner. The PBM was designed in such a way that target probes were synthesized as quadruples of all possible 9-mer combinations, named Q9-UPBM. Also, we developed rice promoter PBM (RPBM) using 19,480 rice promoter sequences containing 40 bp long probe with overlapping 20 bp (cover 1kb from 5’ upstream). We applied RISBZ1 protein, an endosperm specific basic leucine zipper transcription factor, to compare binding site specificities between Q9-UPBM and RPBM and find directly regulated promoter regions through the RPBM. Several cis-elements; Prolamin box (TGTAAAG), GCN4 motif (TGA(G/C)TCA), AACA motif (AACAAAA), and ACGT motif, are highly conserved in the promoters of cereal seed storage protein genes, and play a central role in controlling endosperm specific expression during seed maturation. Characterization of cis-elements and TFs has been performed on many storage protein genes of several crop plants, but the mechanisms are still poorly understood. Two chips provide RISBZ1 could bind to ACGT motif such as a CCACGTCA site and GGATGAC site as well as GCN4 motif known binding site. In RPBM binding affinity to CCACGTCA was highly significant, compared to GGATGAC site. The difference might be caused by the biased presence of specific promoter rather than Q9-UPBM. Also our results will provide direct insight into the importance of combinatorial interplay between cis-elements in regulating the expression of seed storage protein genes.