Molecular analysis of three maize 22 kDa auxin-binding protein genes--transient promoter expression and regulatory regions.
The site I 22 kDa auxin-binding proteins from maize are encoded by a small gene family comprising at least five members. Here the cloning and molecular analysis of the Zm-ERabp1, Zm-ERabp4, and Zm-ERabp5 genes is presented. All three encode 22-23 kDa proteins displaying a transit peptide, a C-terminal KDEL sequence, as well as glycosylation and auxin-binding sites. The Zm-ERabp4 and Zm-ERabp5 genes are very similar. The Zm-ERabp1 gene encodes a related protein, but its promoter, leader and signal peptide are very different. Northern analysis using gene-specific oligonucleotide probes indicates that Zm-ERabp4 is expressed in leaves and coleoptiles but weakly in roots, whereas Zm-ERabp5 expression is barely detectable in these tissues. RNA-PCR indicated that all three genes are none the less expressed in many tissues. Primer-extension analysis revealed an unusually long (320 bases) Zm-ERabp1 leader containing an 80 codon ORF which, if expressed, would encode a positively charged protein with some similarity to transcription factors. In a transient promoter-reporter gene expression system using maize leaf protoplasts the Zm-ERabp1 promoter is more active than the Zm-ERabp4 and Zm-ERabp5 promoters. Promoter deletion analysis of Zm-ERabp1 has identified a negative regulatory sequence in a region from -364 bp and -130 bp, deletion of which results in about twofold higher expression. This region contains both enhancer- and G-box-related sequences. Deletion of -126 bp to +64 bp, which contains the TATA box and transcription start, results in a large decrease in expression.
Schwob
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Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.
Choi
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Simmons
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Migliaccio
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Ilag
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Hesse
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Palme
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Söll
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D000595:Amino Acid Sequence; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D017343:Genes, Plant; D005809:Genes, Regulator; D017930:Genes, Reporter; D007210:Indoleacetic Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators; D010940:Plant Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012313:RNA / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D015183:Restriction Mapping; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014018:Tissue Distribution; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
D018076:DNA, Complementary; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C046131:auxin receptor, plant; D012313:RNA