Principles of ligand binding within a completely buried cavity in HIF2α PAS-B

Jason Key, Thomas H. Scheuermann, Peter C. Anderson, Valerie Daggett, Kevin H. Gardner

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

Hypoxia-inducible factors (HIFs) are heterodimeric transcription factors responsible for the metazoan hypoxia response and promote tumor growth, metastasis, and resistance to cancer treatment. The C-terminal Per-ARNT-Sim (PAS) domain of HIF2α (HIF2α PAS-B) contains a preformed solvent-inaccessible cavity that binds artificial ligands that allosterically perturb the formation of the HIF heterodimer. To better understand how small molecules bind within this domain, we examined the structures and equilibrium and transition-state thermodynamics of HIF2R PAS-B with several artificial ligands using isothermal titration calorimetry, NMR exchange spectroscopy, and X-ray crystallography. Rapid association rates reveal that ligand binding is not dependent upon a slow conformational change in the protein to permit ligand access, despite the closed conformation observed in the NMR and crystal structures. Compensating enthalpic and entropic contributions to the thermodynamic barrier for ligand binding suggest a binding-competent transition state characterized by increased structural disorder. Finally, molecular dynamics simulations reveal conversion between open and closed conformations of the protein and pathways of ligand entry into the binding pocket.

Original languageEnglish (US)
Pages (from-to)17647-17654
Number of pages8
JournalJournal of the American Chemical Society
Volume131
Issue number48
DOIs
StatePublished - Dec 9 2009

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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