TY - JOUR
T1 - Cryo-EM structure of the human α1β3γ2 GABAA receptor in a lipid bilayer
AU - Laverty, Duncan
AU - Desai, Rooma
AU - Uchański, Tomasz
AU - Masiulis, Simonas
AU - Stec, Wojciech J.
AU - Malinauskas, Tomas
AU - Zivanov, Jasenko
AU - Pardon, Els
AU - Steyaert, Jan
AU - Miller, Keith W.
AU - Aricescu, A. Radu
N1 - Funding Information:
Acknowledgements We thank G. Cannone and S. Chen for electron microscopy support; J. Grimmett and T. Darling for computing support; J. García-Nafría, L. Dong, T. Nakane and S. Scheres for advice on electron microscopy data processing; and members of the Aricescu laboratory for assistance with electron microscopy data collection, discussions and comments on the manuscript. This work was supported by the UK Medical Research Council grants MR/L009609/1, MC_UP_1201/15 (A.R.A., D.L. and S.M.) and MC_UP_ A025_1013 (J.Z.); UK Biotechnology and Biological Sciences Research Council grant BB/M024709/1 (A.R.A. and D.L.); Human Frontier Science Program grant RGP0065/2014 (A.R.A.); Cancer Research UK grant C20724/A14414 (T.M.); and Swiss National Science Foundation fellowship 168735 (J.Z.). R.D., W.J.S. and K.W.M. were supported by a grant from the National Institute for General Medical Sciences (GM 58448) and by the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital. We acknowledge the support and the use of resources of Instruct-ERIC (PID1271), part of the European Strategy Forum on Research Infrastructures (ESFRI), and the Research Foundation-Flanders (FWO) for their support of nanobody discovery, and FWO for a doctoral fellowship to T.U.
Publisher Copyright:
© 2019, Springer Nature Limited.
PY - 2019/1/24
Y1 - 2019/1/24
N2 - Type A γ-aminobutyric acid (GABAA) receptors are pentameric ligand-gated ion channels and the main drivers of fast inhibitory neurotransmission in the vertebrate nervous system1,2. Their dysfunction is implicated in a range of neurological disorders, including depression, epilepsy and schizophrenia3,4. Among the numerous assemblies that are theoretically possible, the most prevalent in the brain are the α1β2/3γ2 GABAA receptors5. The β3 subunit has an important role in maintaining inhibitory tone, and the expression of this subunit alone is sufficient to rescue inhibitory synaptic transmission in β1–β3 triple knockout neurons6. So far, efforts to generate accurate structural models for heteromeric GABAA receptors have been hampered by the use of engineered receptors and the presence of detergents7–9. Notably, some recent cryo-electron microscopy reconstructions have reported ‘collapsed’ conformations8,9; however, these disagree with the structure of the prototypical pentameric ligand-gated ion channel the Torpedo nicotinic acetylcholine receptor10,11, the large body of structural work on homologous homopentameric receptor variants12 and the logic of an ion-channel architecture. Here we present a high-resolution cryo-electron microscopy structure of the full-length human α1β3γ2L—a major synaptic GABAA receptor isoform—that is functionally reconstituted in lipid nanodiscs. The receptor is bound to a positive allosteric modulator ‘megabody’ and is in a desensitized conformation. Each GABAA receptor pentamer contains two phosphatidylinositol-4,5-bisphosphate molecules, the head groups of which occupy positively charged pockets in the intracellular juxtamembrane regions of α1 subunits. Beyond this level, the intracellular M3–M4 loops are largely disordered, possibly because interacting post-synaptic proteins are not present. This structure illustrates the molecular principles of heteromeric GABAA receptor organization and provides a reference framework for future mechanistic investigations of GABAergic signalling and pharmacology.
AB - Type A γ-aminobutyric acid (GABAA) receptors are pentameric ligand-gated ion channels and the main drivers of fast inhibitory neurotransmission in the vertebrate nervous system1,2. Their dysfunction is implicated in a range of neurological disorders, including depression, epilepsy and schizophrenia3,4. Among the numerous assemblies that are theoretically possible, the most prevalent in the brain are the α1β2/3γ2 GABAA receptors5. The β3 subunit has an important role in maintaining inhibitory tone, and the expression of this subunit alone is sufficient to rescue inhibitory synaptic transmission in β1–β3 triple knockout neurons6. So far, efforts to generate accurate structural models for heteromeric GABAA receptors have been hampered by the use of engineered receptors and the presence of detergents7–9. Notably, some recent cryo-electron microscopy reconstructions have reported ‘collapsed’ conformations8,9; however, these disagree with the structure of the prototypical pentameric ligand-gated ion channel the Torpedo nicotinic acetylcholine receptor10,11, the large body of structural work on homologous homopentameric receptor variants12 and the logic of an ion-channel architecture. Here we present a high-resolution cryo-electron microscopy structure of the full-length human α1β3γ2L—a major synaptic GABAA receptor isoform—that is functionally reconstituted in lipid nanodiscs. The receptor is bound to a positive allosteric modulator ‘megabody’ and is in a desensitized conformation. Each GABAA receptor pentamer contains two phosphatidylinositol-4,5-bisphosphate molecules, the head groups of which occupy positively charged pockets in the intracellular juxtamembrane regions of α1 subunits. Beyond this level, the intracellular M3–M4 loops are largely disordered, possibly because interacting post-synaptic proteins are not present. This structure illustrates the molecular principles of heteromeric GABAA receptor organization and provides a reference framework for future mechanistic investigations of GABAergic signalling and pharmacology.
UR - http://www.scopus.com/inward/record.url?scp=85060396131&partnerID=8YFLogxK
U2 - 10.1038/s41586-018-0833-4
DO - 10.1038/s41586-018-0833-4
M3 - Article
C2 - 30602789
AN - SCOPUS:85060396131
SN - 0028-0836
VL - 565
SP - 516
EP - 520
JO - Nature
JF - Nature
IS - 7740
ER -