Molecular basis for the constitutive activity of estrogen-related receptor alpha-1.
Some orphan nuclear receptors, including estrogen-related receptor alpha-1 (ERRalpha-1), can activate gene transcription in a constitutive manner. Little is known about the molecular basis of the constitutive activity of these receptors. Our results from site-directed mutagenesis experiments have revealed that Phe-329 (analogous to Ala-350 in estrogen receptor alpha (ERalpha)) is responsible for the constitutive activity of ERRalpha-1. The ERRalpha-1 mutant F329A lost the transactivation activity and acted as a dominant negative mutant. The mammalian cell transfection experiments revealed that the ERRalpha-1 mutant F329A, like wild-type ERalpha, recognized toxaphene (an organochlorine pesticide) as an agonist. This compound was previously shown to be an antagonist of wild-type ERRalpha-1. On the other hand, like wild-type ERRalpha-1, the ERalpha mutant A350F was found to be constitutively active (as demonstrated by mammalian cell transfection and yeast two-hybrid assays). These results indicate that Phe-329 in ERRalpha-1 and Ala-350 in ERalpha play important roles in both ligand binding and transactivation function.
Chen
S
S
Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA. schen@coh.org
Zhou
D
D
Yang
C
C
Sherman
M
M
D000409:Alanine / Q000737:chemistry; D006801:Humans; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010649:Phenylalanine / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000235:genetics* / Q000378:metabolism*; D014112:Toxaphene / Q000494:pharmacology; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques; D000097983:ERRalpha Estrogen-Related Receptor
D000409:Alanine; D008024:Ligands; D010649:Phenylalanine; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen; D014112:Toxaphene; D000097983:ERRalpha Estrogen-Related Receptor