Sites of Anesthetic Inhibitory Action on a Cationic Ligand-Gated Ion Channel

Benoist Laurent (1) , Samuel Murail (1) , Azadeh Shahsavar (2) , Ludovic Sauguet (2) , Marc Delarue (2) , Marc Baaden (1)

1 LBT (UPR_9080) - Laboratoire de biochimie théorique [Paris]
2 Dynamique structurale des Macromolécules / Structural Dynamics of Macromolecules

Pentameric ligand-gated ion channels have been identified as the principal target of general anesthetics (GA), whose molecular mechanism of action remains poorly understood. Bacterial homologs, such as the Gloeobacter violaceus receptor (GLIC), have been shown to be valid functional models of GA action. The GA bromoform inhibits GLIC at submillimolar concentration. We characterize bromoform binding by crystallography and molecular dynamics (MD) simulations. GLIC's open form structure identified three intra-subunit binding sites. We crystallized the locally closed form with an additional bromoform molecule in the channel pore. We systematically compare binding with the multiple potential sites of allosteric channel regulation in the open, locally closed, and resting forms. MD simulations reveal differential exchange pathways between sites from one form to the other. GAs predominantly access the receptor from the lipid bilayer in all cases. Differential binding affinity among the channel forms is observed; the pore site markedly stabilizes the inactive versus active state.

Mots clés: MAXIMUM-LIKELIHOOD; GLYCINE RECEPTORS; GABA(A) RECEPTORS; CENTRAL NEURONS; POTENTIATION; NICOTINIC ACETYLCHOLINE-RECEPTOR; PROPOFOL-BINDING-SITE; ACID TYPE-A; X-RAY-STRUCTURE; STRUCTURAL BASIS

Domaines: Sciences du Vivant [q-bio]

Benoist Laurent, Samuel Murail, Azadeh Shahsavar, Ludovic Sauguet, Marc Delarue, et al.. Sites of Anesthetic Inhibitory Action on a Cationic Ligand-Gated Ion Channel. Structure, 2016, 24 (4), pp.595 - 605. ⟨10.1016/j.str.2016.02.014⟩. ⟨hal-01400467⟩