Looking at nuclear receptors from a new angle

Abstract

While the structures of the DNA- and ligand-binding domains of many nuclear receptors have been determined in great detail; the mechanisms by which these domains interact and possibly 'communicate' is still under debate. The first crystal structures of receptor dimers bound to ligand, DNA and coactivator peptides provided new insights in this matter. The observed binding modes revealed exciting new interaction surfaces between the different nuclear receptor domains. Such interfaces are proposed to be the route through which allosteric signals from the DNA are passed on to the ligand-binding domain and the activating functions of the receptor. The structural determinations of DNA-bound receptor dimers in solution, however, revealed an extended structure of the receptors. Here, we discuss these apparent contradictory structural data and their possible implications for the functioning of nuclear receptors.

Keywords: AF1; AF2; AR; CTE; DBD; DNA binding; DNA binding domain; DR; Domain communication; EM; ER; ERR2; FRET; GR; HNF-4; IR; LBD; MR; NR; NTD; Nuclear receptor; PPAR; PR; RAR; RXR; SANS; SAXS; SF1; Steroid receptor; TR; VDR; activation function 1; activation function 2; aminoterminal domain; androgen receptor; carboxyterminal extension; direct repeat; electron-microscopy; estrogen receptor; estrogen-related receptor 2; fluorescence resonance energy transfer; glucocorticoid receptor; hepatocyte nuclear factor 4; inverted repeat; ligand binding domain; mineralocorticoid receptor; nuclear receptor; peroxisome proliferator-activated receptor; progesterone receptor; retinoic acid receptor; retinoid X receptor; small-angle X-ray scattering; small-angle neutron scattering; steroidogenic factor 1; thyroid receptor; vitamin D receptor.