Determinants of Orexin Receptor Binding and Activation-A Molecular Dynamics Study

J Phys Chem B. 2019 Mar 28;123(12):2609-2622. doi: 10.1021/acs.jpcb.8b10220. Epub 2019 Mar 18.

Abstract

We assess the stability of two previously suggested binding modes for the neuropeptide orexin-A in the OX2 receptor through extensive molecular dynamics simulations. As the activation determinants of the receptor remain unknown, we simulated an unliganded receptor and two small-molecular ligands, the antagonist suvorexant and the agonist Nag26 for comparison. Each system was simulated in pure POPC membrane as well as in the 25% cholesterol-POPC membrane. In total, we carried out 36 μs of simulations. Through this set of simulations, we report a stable binding mode for the C-terminus of orexin-A. In addition, we suggest interactions that would promote orexin receptor activation, as well as others that would stabilize the inactive state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Azepines / metabolism
  • Binding Sites
  • Humans
  • Molecular Dynamics Simulation
  • Orexin Receptor Antagonists / chemistry
  • Orexin Receptor Antagonists / metabolism
  • Orexin Receptors / agonists*
  • Orexin Receptors / chemistry
  • Orexin Receptors / metabolism*
  • Orexins / metabolism
  • Protein Binding
  • Protein Conformation
  • Triazoles / metabolism
  • Water / chemistry

Substances

  • Azepines
  • Orexin Receptor Antagonists
  • Orexin Receptors
  • Orexins
  • Triazoles
  • Water
  • suvorexant