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Letters to Nature

Nature 415, 813-817 (7 February 2002) | doi:10.1038/415813a; Received 8 November 2001; Accepted 12 December 2001

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Structural basis for antagonist-mediated recruitment of nuclear co-repressors by PPARalpha

H. Eric Xu, Thomas B. Stanley, Valerie G. Montana, Millard H. Lambert, Barry G. Shearer, Jeffery E. Cobb, David D. McKee, Cristin M. Galardi, Kelli D. Plunket, Robert T. Nolte, Derek J. Parks, John T. Moore, Steven A. Kliewer, Timothy M. Willson & Julie B. Stimmel

  1. Nuclear Receptor Discovery Research, GlaxoSmithKline, Research Triangle Park, North Carolina 27709, USA

Correspondence to: H. Eric Xu Correspondence and requests for materials should be addressed to H.E.X. (e-mail: Email: ex11957@gsk.com). The Protein Data Bank code for the PPARalpha/GW6471/SMRT complex and the PPARalpha/GW409544/SRC-1 complex is 1KQQ and 1K7L, respectively.

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Repression of gene transcription by nuclear receptors is mediated by interactions with co-repressor proteins such as SMRT and N-CoR1, 2, which in turn recruit histone deacetylases to the chromatin3, 4, 5. Aberrant interactions between nuclear receptors and co-repressors contribute towards acute promyelocytic leukaemia and thyroid hormone resistance syndrome6, 7, 8. The binding of co-repressors to nuclear receptors occurs in the unliganded state, and can be stabilized by antagonists9. Here we report the crystal structure of a ternary complex containing the peroxisome proliferator-activated receptor-alpha ligand-binding domain bound to the antagonist GW6471 and a SMRT co-repressor motif. In this structure, the co-repressor motif adopts a three-turn alpha-helix that prevents the carboxy-terminal activation helix (AF-2) of the receptor from assuming the active conformation. Binding of the co-repressor motif is further reinforced by the antagonist, which blocks the AF-2 helix from adopting the active position. Biochemical analyses and structure-based mutagenesis indicate that this mode of co-repressor binding is highly conserved across nuclear receptors.