Title: Structural basis for high-voltage activation and subtype-specific inhibition of human Nav1.8.

Authors: Xiaoshuang Huang, Xueqin Jin, Gaoxingyu Huang, Jian Huang, Tong Wu, Zhangqiang Li, Jiaofeng Chen, Fang Kong, Xiaojing Pan, Nieng Yan

Journal, date & volume: Proc Natl Acad Sci U S A, 2022Jul26, 119, e2208211119

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/35858452

Abstract
The dorsal root ganglia-localized voltage-gated sodium (Nav) channel Nav1.8 represents a promising target for developing next-generation analgesics. A prominent characteristic of Nav1.8 is the requirement of more depolarized membrane potential for activation. Here we present the cryogenic electron microscopy structures of human Nav1.8 alone and bound to a selective pore blocker, A-803467, at overall resolutions of 2.7 to 3.2 Å. The first voltage-sensing domain (VSDI) displays three different conformations. Structure-guided mutagenesis identified the extracellular interface between VSDI and the pore domain (PD) to be a determinant for the high-voltage dependence of activation. A-803467 was clearly resolved in the central cavity of the PD, clenching S6IV. Our structure-guided functional characterizations show that two nonligand binding residues, Thr397 on S6I and Gly1406 on S6III, allosterically modulate the channel's sensitivity to A-803467. Comparison of available structures of human Nav channels suggests the extracellular loop region to be a potential site for developing subtype-specific pore-blocking biologics.