Ligand-specific structural changes in the vitamin D receptor in solution

Biochemistry. 2011 Dec 27;50(51):11025-33. doi: 10.1021/bi201637p. Epub 2011 Dec 5.

Abstract

Vitamin D receptor (VDR) is a member of the nuclear hormone receptor superfamily. When bound to a variety of vitamin D analogues, VDR manifests a wide diversity of physiological actions. The molecular mechanism by which different vitamin D analogues cause specific responses is not understood. The published crystallographic structures of the ligand binding domain of VDR (VDR-LBD) complexed with ligands that have differential biological activities have exhibited identical protein conformations. Here we report that rat VDR-LBD (rVDR-LBD) in solution exhibits differential chemical shifts when bound to three ligands that cause diverse responses: the natural hormone, 1,25-dihydroxyvitamin D(3) [1,25(OH)₂D₃], a potent agonist analogue, 2-methylene-19-nor-(20S)-1,25-dihydroxyvitamin D₃ [2MD], and an antagonist, 2-methylene-(22E)-(24R)-25-carbobutoxy-26,27-cyclo-22-dehydro-1α,24-dihydroxy-19-norvitamin D₃ [OU-72]. Ligand-specific chemical shifts mapped not only to residues at or near the binding pocket but also to residues remote from the ligand binding site. The complexes of rVDR-LBD with native hormone and the potent agonist 2MD exhibited chemical shift differences in signals from helix-12, which is part of the AF2 transactivation domain that appears to play a role in the selective recruitment of coactivators. By contrast, formation of the complex of rVDR-LBD with the antagonist OU-72 led to disappearance of signals from residues in helices-11 and -12. We present evidence that disorder in this region of the receptor in the antagonist complex prevents the attachment of coactivators.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Bone Density Conservation Agents / chemistry
  • Bone Density Conservation Agents / metabolism
  • Calcitriol / analogs & derivatives*
  • Calcitriol / chemistry
  • Calcitriol / metabolism
  • Databases, Protein
  • Ligands
  • Mediator Complex Subunit 1 / chemistry
  • Mediator Complex Subunit 1 / metabolism
  • Models, Molecular
  • Molecular Conformation
  • Molecular Sequence Data
  • Nuclear Magnetic Resonance, Biomolecular
  • Peptide Fragments / chemistry*
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Protein Interaction Domains and Motifs
  • Protein Structure, Secondary
  • Rats
  • Receptors, Calcitriol / antagonists & inhibitors
  • Receptors, Calcitriol / chemistry*
  • Receptors, Calcitriol / genetics
  • Receptors, Calcitriol / metabolism
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Solubility

Substances

  • 2-methylene-1,25-dihydroxy-19-norvitamin D3
  • 2-methylene-19-nor-(20S)-1alpha,25-dihydroxyvitamin D3
  • Bone Density Conservation Agents
  • Ligands
  • Mediator Complex Subunit 1
  • Peptide Fragments
  • Receptors, Calcitriol
  • Recombinant Fusion Proteins
  • Calcitriol