title: Differential regulation of TGA transcription factors by post-transcriptional control.
abstract: Transcription factors often belong to multigene families and their individual contribution in a particular regulatory network remains difficult to assess. We show here that specific members from a family of conserved Arabidopsis bZIP transcription factors, the TGA proteins, are regulated in their protein stability by developmental stage-specific proteolysis. Using GFP fusions of three different Arabidopsis TGA factors that represent members of distinct subclasses of the TGA factor family, we demonstrate that two of these TGA proteins are specifically targeted for proteolysis in mature leaf cells. Using a supershift gel mobility assay, we found evidence for similar regulation of the cognate proteins as compared to the GFP fusion proteins expressed under the cauliflower mosaic virus (CaMV) 35S promoter. Using various inhibitors, we showed that the expression of at least one of these three TGA factors could be stabilized by inhibition of proteasome-mediated proteolysis. This study indicates that TGA transcription factors may be regulated by distinct pathways of targeted proteolysis that can serve to modulate the contribution of specific members of a multigene family in complex regulatory pathways.
authors.affiliation: Biotech Center, Rutgers State University of New Jersey, Foran Hall, 59 Dudley Road, New Brunswick 08903, USA.
authors.forename: Dominique
authors.initials: D
authors.lastname: Pontier
authors.forename: Isabelle
authors.initials: I
authors.lastname: Privat
authors.forename: Youssef
authors.initials: Y
authors.lastname: Trifa
authors.forename: Jun-Ma
authors.initials: JM
authors.lastname: Zhou
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Klessig
authors.forename: Eric
authors.initials: E
authors.lastname: Lam
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D010447:Peptide Hydrolases / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011499:Protein Processing, Post-Translational; D014026:Nicotiana / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D010940:Plant Proteins; C065794:TGA1a protein, Nicotiana tabacum; D014157:Transcription Factors; D010447:Peptide Hydrolases