Regulation of DNA binding and trans-activation by a xenobiotic stress-activated plant transcription factor.
As-1-type cis-elements augment transcription of both nuclear and pathogen genes in response to stress and defense cues in plants. Basic/leucine zipper proteins termed "TGA factors" that specifically bind as-1 elements are likely candidates for mediating these transcription activities. Our earlier work has shown that 2, 4-dichlorophenoxyacetic acid-induced xenobiotic stress enhances trans-activation by a chimeric fusion protein of the yeast Gal4 binding domain and TGA1a, a TGA factor of tobacco. Here we demonstrate that xenobiotic stress also enhances the ability of native TGA1a to bind as-1 and activate transcription of a known target gene. In addition, the previously identified xenobiotic stress-responsive domain of TGA1a was found to inhibit this factor's trans-activation potential by a mechanism that appears to involve stimulus-reversible interactions with a nuclear repressor protein. Results from these and other studies can now be placed in the context of a working model to explain basal and xenobiotic stress-induced activities of TGA1a through its cognate cis-acting element.
Johnson
C
C
Center for Agricultural Biotechnology, University of Maryland, College Park, Maryland 20742, USA.
Glover
G
G
Arias
J
J
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D050976:Basic-Leucine Zipper Transcription Factors; D002478:Cells, Cultured; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017930:Genes, Reporter; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000032:analysis / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010947:Plants, Toxic; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins; D020218:Response Elements / Q000235:genetics; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects*; D014162:Transfection; D015262:Xenobiotics / Q000494:pharmacology*
D050976:Basic-Leucine Zipper Transcription Factors; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C065794:TGA1a protein, Nicotiana tabacum; D014157:Transcription Factors; D015262:Xenobiotics; D015084:2,4-Dichlorophenoxyacetic Acid