Direct Pore Binding as a Mechanism for Isoflurane Inhibition of the Pentameric Ligand-gated Ion Channel ELIC.
Pentameric ligand-gated ion channels (pLGICs) are targets of general anesthetics, but molecular mechanisms underlying anesthetic action remain debatable. We found that ELIC, a pLGIC from Erwinia chrysanthemi, can be functionally inhibited by isoflurane and other anesthetics. Structures of ELIC co-crystallized with isoflurane in the absence or presence of an agonist revealed double isoflurane occupancies inside the pore near T237(6') and A244(13'). A pore-radius contraction near the extracellular entrance was observed upon isoflurane binding. Electrophysiology measurements with a single-point mutation at position 6' or 13' support the notion that binding at these sites renders isoflurane inhibition. Molecular dynamics simulations suggested that isoflurane binding was more stable in the resting than in a desensitized pore conformation. This study presents compelling evidence for a direct pore-binding mechanism of isoflurane inhibition, which has a general implication for inhibitory action of general anesthetics on pLGICs.
Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.
Qiang
Q
Chen
Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.
Monica N
MN
Kinde
Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.|Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.
Palaniappa
P
Arjunan
Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.|Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.
Marta M
MM
Wells
Stanford Synchrotron Radiation Lightsource, 2575 Sand Hill Road, MS: 99, Menlo Park, California 94025, USA.
Aina E
AE
Cohen
Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.|Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.|Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.
Yan
Y
Xu
Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.|Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.|Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260, USA.
Pei
P
Tang
D018685:Anesthetics, Inhalation / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D004305:Dose-Response Relationship, Drug; D007530:Isoflurane / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D058446:Ligand-Gated Ion Channels / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization
D018685:Anesthetics, Inhalation; D058446:Ligand-Gated Ion Channels; D007530:Isoflurane