Barley BLZ1: a bZIP transcriptional activator that interacts with endosperm-specific gene promoters.
A cDNA encoding a bZIP transcription factor was obtained from barley endosperm and used to identify the corresponding gene from a genomic library. The gene, designated Blz1, contained six exons and five introns, plus a 442 nt-long 5'-untranslated leader sequence, and was located on chromosome 5H. The Blz1 mRNA was detected early in endosperm development and was also expressed in roots and leaves. The BLZ1 protein was a potent transcriptional activator in a yeast system; 85% of its activity was associated with the first 203 amino acid residues at the N-terminus, which included two acidic regions. Presumptive involvement of Blz1 in the regulation of gene expression in endosperm was ascertained by the DNA-binding properties of BLZ1 in electrophoretic mobility shift assays (EMSA) and by transient expression in barley developing endosperms, using, as effectors, Blz1 in both sense and anti-sense orientations. In the co-bombardment experiments, the beta-glucuronidase (GUS) reported gene responded to Blz1 if under the control of the endosperm-specific ltr1 promoter or under a synthetic promoter containing the endosperm box of gene Hor2. Sucrose synthase promoters Ss1 and Ss2 and synthetic promoters containing mutated sequences of Hor2 were unaffected in trans by Blz1.
Vicente-Carbajosa
J
J
Departamento Biotecnología-UPM, Madrid, Spain.
Oñate
L
L
Lara
P
P
Diaz
I
I
Carbonero
P
P
D000595:Amino Acid Sequence; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001665:Binding Sites / Q000235:genetics; D002874:Chromosome Mapping; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D017343:Genes, Plant; D017930:Genes, Reporter; D005966:Glucuronidase / Q000235:genetics; D001467:Hordeum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
C118447:BLZ1 protein, Hordeum vulgare; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D018076:DNA, Complementary; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D015534:Trans-Activators; D014157:Transcription Factors; D005966:Glucuronidase