期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：30
DOI：10.1073/pnas.2208211119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Pain management represents an unmet healthcare need in many countries. Na
v1.8 represents a potential target for developing nonaddictive analgesics. Here we present the cryogenic electron microscopy (cryo-EM) structures of human Na
v1.8 alone and bound to a selective pore blocker, A-803467. Unlike reported structures of eukaryotic Na
v channels wherein the first voltage-sensing domain (VSD
I) is well-resolved in one stable conformation, different conformations of VSD
I are observed in the cryo-EM maps of Na
v1.8. An extracellular interface between VSD
I and the pore domain was identified to be a determinant for Na
v1.8’s dependence on higher voltage for activation. A-803467 clenches S6
IV within the central cavity. Unexpectedly, the channel selectivity for A-803467 is determined by nonligand coordinating residues through an allosteric mechanism.
The dorsal root ganglia–localized voltage-gated sodium (Na
v) channel Na
v1.8 represents a promising target for developing next-generation analgesics. A prominent characteristic of Na
v1.8 is the requirement of more depolarized membrane potential for activation. Here we present the cryogenic electron microscopy structures of human Na
v1.8 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 (VSD
I) displays three different conformations. Structure-guided mutagenesis identified the extracellular interface between VSD
I 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 S6
IV. Our structure-guided functional characterizations show that two nonligand binding residues, Thr397 on S6
I and Gly1406 on S6
III, allosterically modulate the channel’s sensitivity to A-803467. Comparison of available structures of human Na
v channels suggests the extracellular loop region to be a potential site for developing subtype-specific pore-blocking biologics.
