An as-1-like motif controls the level of expression of the gene for the pathogenesis-related protein 1a from tobacco.
Pathogenesis-related proteins of group 1 (PR-1) are strongly induced in plants by pathogen attack, exposure of the plants to (acetyl)salicylic acid (ASA, SA), and by developmental cues. Functional analysis of the PR-1a promoter identified a region of 139 bp (from -691 to -553) mediating expression of the GUS reporter gene in response to ASA. Inspection of this region revealed two TGACG elements reminiscent of activation sequence-1 (as-1). Recently, as-1 has been reported to be responsive to SA in the context of the CaMV 35S RNA promoter. To address the question of whether the as-1-like sequence may be of functional significance for the expression of the PR-1a gene, gel shift assays were performed with TGA1a, a protein been shown to interact with as-1 in vitro. TGA1a was found to bind to the PR-1a as-1-like sequence with similar specificity and affinity as to as-1. Furthermore, mutations were introduced in the as-1-like sequence in the context of the inducible 906 bp PR-1a promoter which are impaired in binding TGA1a in vitro. Significantly reduced levels of GUS reporter gene activity were obtained with the mutant promoter regions as compared to the wild-type PR-1a promoter in response to all stimuli in transgenic tobacco plants. Yet, mutation of the as-1-like sequence did not abolish induction of reporter gene expression. Taken together, these results suggest that the level of expression of the tobacco PR-1a gene is controlled by an as-1-like sequence motif in the PR-1a upstream region, possibly interacting with a factor related to TGA1a.
Universität Hohenheim, Institut für Genetik, FG Allgemeine Virologie, Stuttgart, Germany.
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D050976:Basic-Leucine Zipper Transcription Factors; D017796:Caulimovirus / Q000235:genetics; D018744:DNA, Plant / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D017930:Genes, Reporter; D005966:Glucuronidase / Q000235:genetics; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins; D012459:Salicylates / Q000494:pharmacology; D020156:Salicylic Acid; D014026:Nicotiana / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics*
D050976:Basic-Leucine Zipper Transcription Factors; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D012459:Salicylates; C065794:TGA1a protein, Nicotiana tabacum; C053376:pathogenesis-related proteins, plant; D005966:Glucuronidase; D020156:Salicylic Acid