The yeast Ada complex mediates the ligand-dependent activation function AF-2 of retinoid X and estrogen receptors.
Nuclear receptors can function as ligand-inducible transregulators in both mammalian and yeast cells, indicating that important features of control of transcription have been conserved throughout evolution. Here, we report the isolation and characterization of a yeast protein that exhibits properties expected for a coactivator/mediator of the ligand-dependent activation function AF-2 present in the ligand-binding domain (LBD, region E) of the retinoid X (RXRalpha) and estrogen (ERalpha) receptors. This protein is identical to Ada3, a component of the yeast Ada coactivator complex. We demonstrate that: (1) the region encompassing residues 347-702 of Ada3 interacts with the LBD of RXRalpha and ERalpha in a ligand-dependent manner in yeast; (2) this interaction corresponds to a direct binding and requires the integrity of the core of the AF-2 activating domain (AF-2 AD) of both RXRalpha and ERalpha; (3) Ada3 as well as Ada2 and Gcn5, two other components of the Ada complex, are required for maximal AF-2 activity in yeast; and (4) Ada3 is able to enhance the AF-2 activity of RXRalpha and ERalpha when overexpressed in yeast and mammalian cells. Taken together, these data indicate that ligand-dependent transactivation by RXRalpha and ERalpha in yeast is mediated at least in part by the Ada complex, in which the Ada3 subunit directly binds to the holoreceptor LBD.
vom Baur
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Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Centre National de la Recherche Scientifique-Institut National de la Santé et de la Recherche Médicale-Université Louis Pasteur (CNRS-INSERM-ULP), Collège de France,
Harbers
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Um
S J
SJ
Benecke
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Chambon
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Losson
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D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008024:Ligands; D051379:Mice; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D047488:Retinoid X Receptors; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
D005656:Fungal Proteins; D008024:Ligands; C083323:NGG1 protein, S cerevisiae; D009687:Nuclear Proteins; D011960:Receptors, Estrogen; D018168:Receptors, Retinoic Acid; D011993:Recombinant Fusion Proteins; D047488:Retinoid X Receptors; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors