Conformational Changes of RORγ During Response Element Recognition and Coregulator Engagement.

The retinoic acid receptor-related orphan receptor {gamma} (ROR{gamma}) is a ligand-dependent transcription factor of the nuclear receptor super family that underpins metabolic activity, immune function, and cancer progression. Despite being a valuable drug target in health and disease, our understanding of the ligand-dependent activities of ROR{gamma} is far from complete. Like most nuclear receptors, ROR{gamma} must recruit coregulatory protein to enact the ROR{gamma} target gene program. To date, a majority of structural studies have been focused exclusively on the ROR{gamma} ligand-binding domain and the ligand-dependent recruitment of small peptide segments of coregulators. Herein, we examine the ligand-dependent assembly of full length ROR{gamma}:coregulator complexes on cognate DNA response elements using structural proteomics and small angle x-ray scattering. The results from our studies suggest that ROR{gamma} becomes elongated upon DNA recognition, preventing long range interdomain crosstalk. We also determined that the DNA binding domain adopts a sequence-specific conformation, and that coregulatory proteins may be able to sense the ligand- and DNA-bound status of ROR{gamma}. We propose a model where ligand-dependent coregulator recruitment may be influenced by the sequence of the DNA to which ROR{gamma} is bound. Overall, the efforts described herein will illuminate important aspects of full length ROR{gamma} and monomeric orphan nuclear receptor target gene regulation through DNA-dependent conformational changes. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=81 SRC="FIGDIR/small/445650v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@1f0a067org.highwire.dtl.DTLVardef@b2e9f6org.highwire.dtl.DTLVardef@1e15d5org.highwire.dtl.DTLVardef@12b8546_HPS_FORMAT_FIGEXP M_FIG C_FIG