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.
Departamento Biotecnología-UPM, Madrid, Spain.
J
J
Vicente-Carbajosa
L
L
Oñate
P
P
Lara
I
I
Diaz
P
P
Carbonero
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