The bifactorial endosperm box of gamma-zein gene: characterisation and function of the Pb3 and GZM cis-acting elements.
The proximal region of the gamma-zein promoter (gamma Z) has a functional bifactorial prolamin box element containing two cis-acting elements, a prolamin-box motif (Pb3) and a GCN4-like motif (GZM). By particle bombardment of maize endosperms with 5' deletions and internal deletions of gamma Z fused to the GUS gene, we have shown that a 135 bp region containing the bifactorial element is involved in the transcriptional activation of the gamma Z promoter. However, the 135 bp region was unable to activate the gamma Z promoter in the absence of a 84 bp downstream sequence. Using in vivo footprinting and gel mobility shift assays with 15 DAP endosperm nuclear extracts, we have demonstrated the presence of trans-acting factors that interact with Pb3 and GZM target sites. Base-substitution mutations within Pb3 and GZM decreased transcription activity of the gamma Z promoter suggesting a co-ordinated function between the two cis-acting elements. Two additional cis-motifs upstream of the bifactorial prolamin element have been identified: a motif with high homology to the AACA elements of rice glutelin genes and an AZM motif containing an ACGT core which binds nuclear proteins other than the Opaque 2 (O2).
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Departament de Genètica Molecular, Centre de Investigació i Desenvolupament, (C.S.I.C.), Barcelona, Spain.
Busk
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Ludevid
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Torrent
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D001483:Base Sequence; D018983:DNA Footprinting; D018744:DNA, Plant / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics; D004742:Enhancer Elements, Genetic; D005656:Fungal Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010940:Plant Proteins / Q000235:genetics; D055315:Prolamins; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid; D015028:Zein / Q000235:genetics*
D018744:DNA, Plant; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D010940:Plant Proteins; D055315:Prolamins; D029701:Saccharomyces cerevisiae Proteins; D015028:Zein; D011494:Protein Kinases