A critical residue in the ?₁M2-M3 linker regulating mammalian GABA_A receptor pore gating by diazepam.

ABSTRACT: Benzodiazepines (BZDs) are a class of widely prescribed psychotropic drugs that modulate activity of GABA_A receptors (GABA_ARs), neurotransmitter-gated ion channels critical for synaptic transmission. However, the physical basis of this modulation is poorly understood. We explore the role of an important gating domain, the ?₁M2-M3 linker, in linkage between the BZD site and pore gate. To probe energetics of this coupling without complication from bound agonist, we use a gain of function mutant (?₁L9'T?₂?_2L) directly activated by BZDs. We identify a specific residue whose mutation (?₁V279A) more than doubles the energetic contribution of the BZD positive modulator diazepam (DZ) to pore opening and also enhances DZ potentiation of GABA-evoked currents in a wild-type background. In contrast, other linker mutations have little effect on DZ efficiency, but generally impair unliganded pore opening. Our observations reveal an important residue regulating BZD-pore linkage, thereby shedding new light on the molecular mechanism of these drugs.

SUBMITTER: Nors JW 

PROVIDER: S-EPMC7899671 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature