Glycine receptor mechanism elucidated by electron cryo-microscopy.
The strychnine-sensitive glycine receptor (GlyR) mediates inhibitory synaptic transmission in the spinal cord and brainstem and is linked to neurological disorders, including autism and hyperekplexia. Understanding of molecular mechanisms and pharmacology of glycine receptors has been hindered by a lack of high-resolution structures. Here we report electron cryo-microscopy structures of the zebrafish α1 GlyR with strychnine, glycine, or glycine and ivermectin (glycine/ivermectin). Strychnine arrests the receptor in an antagonist-bound closed ion channel state, glycine stabilizes the receptor in an agonist-bound open channel state, and the glycine/ivermectin complex adopts a potentially desensitized or partially open state. Relative to the glycine-bound state, strychnine expands the agonist-binding pocket via outward movement of the C loop, promotes rearrangement of the extracellular and transmembrane domain 'wrist' interface, and leads to rotation of the transmembrane domain towards the pore axis, occluding the ion conduction pathway. These structures illuminate the GlyR mechanism and define a rubric to interpret structures of Cys-loop receptors.
Vollum Institute, Oregon Health &Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
Juan
J
Du
Vollum Institute, Oregon Health &Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
Wei
W
Lü
Department of Biochemistry and Biophysics, University of California San Francisco, 600 16th Street, San Francisco, California 94158, USA.
Shenping
S
Wu
Department of Biochemistry and Biophysics, University of California San Francisco, 600 16th Street, San Francisco, California 94158, USA.
Yifan
Y
Cheng
Vollum Institute, Oregon Health &Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.|Howard Hughes Medical Institute, Oregon Health &Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
Eric
E
Gouaux
D000494:Allosteric Regulation; D000818:Animals; D001665:Binding Sites; D020285:Cryoelectron Microscopy; D005998:Glycine / Q000378:metabolism / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects; D007559:Ivermectin / Q000378:metabolism / Q000494:pharmacology; D008958:Models, Molecular; D018377:Neurotransmitter Agents / Q000378:metabolism / Q000494:pharmacology; D011487:Protein Conformation / Q000187:drug effects; D021122:Protein Subunits / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D018009:Receptors, Glycine / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000648:ultrastructure*; D012399:Rotation; D015398:Signal Transduction; D013331:Strychnine / Q000378:metabolism / Q000494:pharmacology; D015027:Zebrafish
D018377:Neurotransmitter Agents; D021122:Protein Subunits; D018009:Receptors, Glycine; D007559:Ivermectin; D013331:Strychnine; D005998:Glycine