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Title: Structural basis of neurosteroid anesthetic action on GABAA receptors

Journal Article · · Nature Communications

Type A γ-aminobutyric acid receptors (GABAARs) are inhibitory pentameric ligand-gated ion channels in the brain. Many anesthetics and neurosteroids act through binding to the GABAAR transmembrane domain (TMD), but the structural basis of their actions is not well understood and no resting-state GABAAR structure has been determined. Here, we report crystal structures of apo and the neurosteroid anesthetic alphaxalone-bound desensitized chimeric α1GABAAR (ELIC-α1GABAAR). The chimera retains the functional and pharmacological properties of GABAARs, including potentiation, activation and desensitization by alphaxalone. The apo-state structure reveals an unconventional activation gate at the intracellular end of the pore. The desensitized structure illustrates molecular determinants for alphaxalone binding to an inter-subunit TMD site. These structures suggest a plausible signaling pathway from alphaxalone binding at the bottom of the TMD to the channel gate in the pore-lining TM2 through the TM1–TM2 linker. The study provides a framework to discover new GABAAR modulators with therapeutic potential.

Research Organization:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER)
Grant/Contract Number:
AC02-76SF00515; R01GM056257; TG-MCB050030N; W-31-109-Eng-38
OSTI ID:
1529559
Journal Information:
Nature Communications, Vol. 9, Issue 1; ISSN 2041-1723
Publisher:
Nature Publishing GroupCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 43 works
Citation information provided by
Web of Science

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Cited By (5)

GABAA receptor signalling mechanisms revealed by structural pharmacology journal January 2019
Identification of naturally originated molecules as γ-aminobutyric acid receptor antagonist journal February 2020
Binding site location on GABA A receptors determines whether mixtures of intravenous general anaesthetics interact synergistically or additively in vivo journal December 2019
Brexanolone, a neurosteroid antidepressant, vindicates the GABAergic deficit hypothesis of depression and may foster resilience journal January 2019
Ginsenoside Rb1 regulates prefrontal cortical GABAergic transmission in MPTP-treated mice journal July 2019

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