Developmental and tissue-specific regulation of the gene for the wheat basic/leucine zipper protein HBP-1a(17) in transgenic Arabidopsis plants.
Wheat basic/leucine zipper protein HBP-1a(17) binds in vitro specifically to ACGT motif-containing cis-acting elements, such as the type I element of plant histone promoters and the G-box of hormone- and light-inducible promoters. To address the in vivo function of HBP-1a(17), we isolated and structurally analyzed the HBP-1a(17) gene and examined its expression in transgenic Arabidopsis plants. The HBP-1a(17) gene is composed of 14 exons; the basic region and leucine zipper are encoded by separate small exons, as is the case for other bZIP protein genes. The G-box of the HBP-1a(17) promoter bound specifically to HBP-1a(17) and its related HBP-1a isoforms, suggesting that the HBP-1a(17) gene may be autoregulated, although the binding affinity of these proteins in vitro is very low. In Arabidopsis plants, activation of the HBP-1a(17) promoter was highly restricted to photosynthetically active mesophyll, and guard cells and vascular bundles of vegetative leaves. Etiolation of transgenic plants resulted in inhibition of expression of the HBP-1a(17) promoter. Indeed, the HBP-1a(17) promoter contains several sequence elements homologous to cis-acting elements conserved in light-inducible promoters. It is, therefore, assumed that the HBP-1a(17) gene is light regulated and that HBP-1a(17) is involved in light-responsive gene transcription via the G-box.
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics*; D014908:Triticum / Q000235:genetics*
D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; C068756:HBP-1a protein, Triticum aestivum; D009687:Nuclear Proteins; D010940:Plant Proteins; D014157:Transcription Factors