DNA-binding properties, genomic organization and expression pattern of TGA6, a new member of the TGA family of bZIP transcription factors in Arabidopsis thaliana

The TGA genes encode a family of basic domain-leucine zipper (bZIP) transcription factors that are conserved in higher plants. We have continued to unravel the complexity of this gene family by using a polymerase chain reaction (PCR)-based approach. Taking advantage of the conserved amino acid sequence in the bZIP domain found in all members of this gene family, two degenerate oligonucleotides were synthesized based on the sequence of this region in order to amplify by PCR the analogous genomic fragments from the various TGA loci in Arabidopsis. This approach has led us to the finding of a new member of the TGA gene family, and subsequently the isolation of a gene designated as TGA6. Further characterization of the TGA6 locus confirmed our prediction that the gene structure of this family is remarkably conserved. Genomic Southern blot analysis revealed that TGA6 is a single-copy gene in Arabidopsis. Based on the genomic sequence information, gene-specific primers were synthesized for isolating the cDNA that corresponds to the coding region. Subsequently, the cDNA for TGA6 was cloned and sequenced. Gel mobility shift assays with in vitro translated TGA6 protein showed that TGA6 is more like TGA5 in terms of its in vitro DNA-binding properties. The expression of TGA6 in different tissues was estimated by using reverse transcriptase (RT)-PCR and further analyzed in transgenic Arabidopsis lines expressing a TGA6 promoter-GUS fusion. TGA6 promoter activity is found primarily in roots of young seedlings. As seedlings develop, TGA6 is expressed in aging cotyledons, mesophyll cells of hydathodes on leaf margins, vascular tissue and trichomes of senescing rosette leaves, but is very low in primary roots of mature plants. High levels of expression persist in young lateral roots and in regions of the primary root where lateral roots are emerging. In flowers, the activity is localized predominantly to mature pollen grains. The expression pattern of TGA6 reported here is strikingly similar to that of an Arabidopsis acidic chitinase gene. Possible biological significance of TGA6 in cellular defense against pathogens and abiotic stress is discussed.

[1]  F. Sanger,et al.  DNA sequencing with chain-terminating inhibitors. , 1977, Proceedings of the National Academy of Sciences of the United States of America.

[2]  M. Bevan,et al.  GUS fusions: beta‐glucuronidase as a sensitive and versatile gene fusion marker in higher plants. , 1987, The EMBO journal.

[3]  G. An.  BINARY TI VECTORS FOR PLANT TRANSFORMATION AND PROMOTER ANALYSIS , 1987 .

[4]  S. McKnight,et al.  The leucine zipper: a hypothetical structure common to a new class of DNA binding proteins. , 1988, Science.

[5]  F. Katagiri,et al.  An octopine synthase enhancer element directs tissue-specific expression and binds ASF-1, a factor from tobacco nuclear extracts. , 1989, The Plant cell.

[6]  F. Katagiri,et al.  Two tobacco DNA-binding proteins with homology to the nuclear factor CREB , 1989, Nature.

[7]  B. Franza,et al.  The product of a fos-related gene, fra-1, binds cooperatively to the AP-1 site with Jun: transcription factor AP-1 is comprised of multiple protein complexes. , 1989, Genes & development.

[8]  P. Benfey,et al.  Site-specific mutations alter in vitro factor binding and change promoter expression pattern in transgenic plants. , 1989, Proceedings of the National Academy of Sciences of the United States of America.

[9]  F. Katagiri,et al.  TGA1a, a tobacco DNA-binding protein, increases the rate of initiation in a plant in vitro transcription system , 1990, Proceedings of the National Academy of Sciences of the United States of America.

[10]  F. Katagiri,et al.  TGA1a, a tobacco DNA-binding protein, increases the rate of preinitiation complex formation in a plant in vitro transcription system [corrected] , 1990, Proceedings of the National Academy of Sciences of the United States of America.

[11]  F. Katagiri,et al.  Plant nuclear factor ASF-1 binds to an essential region of the nopaline synthase promoter. , 1990, The Journal of biological chemistry.

[12]  F. Katagiri,et al.  Erratum: TGA1a, a tobacco DNA-binding protein, increases the rate of initiation in a plant in vitro transcription system (Proc. Natl. Acad. Sci. USA (September 1990) 87 (7035-7039)) , 1990 .

[13]  Tsonwin Hai,et al.  Cross-family dimerization of transcription factors Fos/Jun and ATF/CREB alters DNA binding specificity. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[14]  D. Shah,et al.  Developmental and Pathogen-Induced Activation of the Arabidopsis Acidic Chitinase Promoter. , 1991, The Plant cell.

[15]  K. Struhl,et al.  ACR1, a yeast ATF/CREB repressor. , 1992, Molecular and cellular biology.

[16]  Y. Shimura,et al.  A cDNA clone encoding HBP-1b homologue in Arabidopsis thaliana. , 1992, Nucleic acids research.

[17]  A. Cashmore,et al.  TGA1 and G-box binding factors: two distinct classes of Arabidopsis leucine zipper proteins compete for the G-box-like element TGACGTGG. , 1992, The Plant cell.

[18]  H. Hurst,et al.  Transcriptional repression by a novel member of the bZIP family of transcription factors , 1992, Molecular and cellular biology.

[19]  R. Foley,et al.  Isolation and characterization of two related Arabidopsis ocs-element bZIP binding proteins. , 1993, The Plant journal : for cell and molecular biology.

[20]  J. Ellis,et al.  In planta Agrobacterium mediated gene transfer by infiltration of adult Arabidopsis thaliana plants , 1993 .

[21]  B Zhang,et al.  ocs element promoter sequences are activated by auxin and salicylic acid in Arabidopsis. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[22]  X. Qin,et al.  Immediate early transcription activation by salicylic acid via the cauliflower mosaic virus as-1 element. , 1994, The Plant cell.

[23]  Frans,et al.  Genes Galore: A Summary of Methods for Accessing Results from Large-Scale Partial Sequencing of Anonymous Arabidopsis cDNA Clones , 1994, Plant physiology.

[24]  F. Katagiri,et al.  Tissue-Specific Expression of as-1 in Transgenic Tobacco. , 1994, The Plant cell.

[25]  E. Lam,et al.  Two binding sites for the plant transcription factor ASF-1 can respond to auxin treatments in transgenic tobacco. , 1994, The Journal of biological chemistry.

[26]  C. Gatz,et al.  A dominant negative mutant of PG13 suppresses transcription from a cauliflower mosaic virus 35S truncated promoter in transgenic tobacco plants. , 1994, The Plant cell.

[27]  M. Karin,et al.  Antitumor promotion by phenolic antioxidants: inhibition of AP-1 activity through induction of Fra expression. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[28]  E. Lam,et al.  Binding site requirements and differential representation of TGF factors in nuclear ASF-1 activity. , 1995, Nucleic acids research.

[29]  R. Foley,et al.  Interactions between distinct types of DNA binding proteins enhance binding to ocs element promoter sequences. , 1995, The Plant cell.

[30]  E. Lam,et al.  Targeted disruption of the TGA3 locus in Arabidopsis thaliana. , 1995, The Plant journal : for cell and molecular biology.

[31]  E. Komor,et al.  The Electronic Plant Gene Register , 1995 .

[32]  E. Lam,et al.  Construction of a trans-dominant inhibitor for members of the TGA family of transcription factors conserved in higher plants. , 1995, The Plant journal : for cell and molecular biology.

[33]  B. J. van der Zaal,et al.  Auxin-Sensitive Elements from Promoters of Tobacco GST Genes and a Consensus as-1-Like Element Differ Only in Relative Strength , 1996, Plant physiology.

[34]  Y. Takahashi,et al.  A Multiple-Stimuli-Responsive as-1-Related Element of parA Gene Confers Responsiveness to Cadmium but Not to Copper , 1996, Plant physiology.

[35]  P. Hooykaas,et al.  Promoter analysis of the auxin-regulated tobacco glutathione S-transferase genes Nt103-1 and Nt103-35 , 1995, Plant Molecular Biology.

[36]  E. Lam,et al.  TGA3 is a distinct member of the TGA family of bZIP transcription factors in Arabidopsis thaliana , 1994, Plant Molecular Biology.

[37]  F. Katagiri,et al.  The tobacco transcription activator TGA1a binds to a sequence in the 5′ upstream region of a gene encoding a TGA1a-related protein , 1991, Molecular and General Genetics MGG.

[38]  E. Lam,et al.  Coordinated activation of as-1-type elements and a tobacco glutathione S-transferase gene by auxins, salicylic acid, methyl-jasmonate and hydrogen peroxide , 1996, Plant Molecular Biology.

[39]  Michael A. Costa,et al.  Phenotypic alterations of petal and sepal by ectopic expression of a rice MADS box gene in tobacco , 1995, Plant Molecular Biology.

[40]  Michael A. Costa,et al.  A 20 nucleotide upstream element is essential for the nopaline synthase (nos) promoter activity , 2004, Plant Molecular Biology.

[41]  H. Hirt,et al.  The plant transcription factor TGA1 stimulates expression of the CaMV 35S promoter in Saccharomyces cerevisiae , 1994, Plant Molecular Biology.