title: TFE3 contains two activation domains, one acidic and the other proline-rich, that synergistically activate transcription.
abstract: TFE3 is a basic-helix-loop-helix-zipper (bHLHZIP) domain-containing protein that binds mu E3 sites in regulatory elements in the immunoglobulin heavy chain gene. The protein is a transcriptional activator that is expressed in vivo as two alternately spliced isoforms with different activating properties: TFE3L contains an N-terminal acidic activation domain; TFE3S lacks this activation domain and is a dominant negative inhibitor of TFE3L. We show that TFE3L and TFE3S contain a second, C-terminal activation domain rich in proline residues. This pro-rich activation domain has activity in a Gal4 fusion assay comparable to the N-terminal acidic activation domain present in TFE3L. The TFE3 pro-rich activation domain contains regions of strong homology with the related proteins microphthalmia and TFEB, suggesting that these regions are important for function. Using two different assays, we show that the N- and C-terminal activation domains of TFE3 act synergistically. This synergism explains in part the ability of TFE3S to act as a dominant negative. Our domain analysis of TFE3 is incorporated into a general structural model for the TFE3 protein that predicts that the activation domains of TFE3 will be widely separated in space.
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001665:Binding Sites; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D018257:Helix-Loop-Helix Motifs; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D016350:Leucine Zippers; D008156:Luciferases / Q000235:genetics; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins; D012045:Regulatory Sequences, Nucleic Acid; D029701:Saccharomyces cerevisiae Proteins; D017385:Sequence Homology; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D007143:Immunoglobulin Heavy Chains; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C069203:TFE3 protein, human; D014157:Transcription Factors; D004247:DNA; D008156:Luciferases