Ligand-induced peroxisome proliferator-activated receptor alpha conformational change.

Structurally diverse peroxisome proliferators and related compounds that have been demonstrated to induce the ligand-dependent transcriptional activation function of mouse peroxisome proliferator-activated receptor alpha (mPPARalpha) in transfection experiments were tested for the ability to induce conformational changes within mPPARalpha in vitro. WY-14,643, 5,8,11,14-eicosatetraynoic acid, LY-171883, and clofibric acid all directly induced mPPARalpha conformational changes as evidenced by a differential protease sensitivity assay. Carboxyl-terminal truncation mutagenesis of mPPARalpha differentially affected the ability of these ligands to induce conformational changes suggesting that PPAR ligands may make distinct contacts with the receptor. Direct interaction of peroxisome proliferators and related compounds with, and the resulting conformational alteration(s) in, mPPARalpha may facilitate interaction of the receptor with transcriptional intermediary factors and/or the general transcription machinery and, thus, may underlie the molecular basis of ligand-dependent transcriptional activation mediated by mPPARalpha.