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：33
DOI：10.1073/pnas.2209164119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Na
v1.7 has been targeted for pain management for its well-established role in pain sensation. Hundreds of mutations of Na
v1.7 have been found in patients with pain disorders. Structures of Na
v1.7 captured in different conformations will reveal its working mechanism and facilitate drug discovery. Here we present the rational design of a Na
v1.7 variant, Na
v1.7-M11, that may be trapped in the closed-state inactivation conformation at 0 mV. Cryoelectron microscopy analysis of Na
v1.7-M11 reveals voltage-sensing domain in the first repeat (VSD
I) in the completely down conformation, VSD
II at an intermediate state, and the pore domain tightly closed. Structural comparison of Na
v1.7-M11 with the WT channel provides unprecedented insight into the electromechanical coupling details and affords mechanistic interpretation for a number of pain-related mutations.
Voltage-gated sodium (Na
v) channel Na
v1.7 has been targeted for the development of nonaddictive pain killers. Structures of Na
v1.7 in distinct functional states will offer an advanced mechanistic understanding and aid drug discovery. Here we report the cryoelectron microscopy analysis of a human Na
v1.7 variant that, with 11 rationally introduced point mutations, has a markedly right-shifted activation voltage curve with V
1/2 reaching 69 mV. The voltage-sensing domain in the first repeat (VSD
I) in a 2.7-Å resolution structure displays a completely down (deactivated) conformation. Compared to the structure of WT Na
v1.7, three gating charge (GC) residues in VSD
I are transferred to the cytosolic side through a combination of helix unwinding and spiral sliding of S4
I and ∼20° domain rotation. A conserved WNФФD motif on the cytoplasmic end of S3
I stabilizes the down conformation of VSD
I. One GC residue is transferred in VSD
II mainly through helix sliding. Accompanying GC transfer in VSD
I and VSD
II, rearrangement and contraction of the intracellular gate is achieved through concerted movements of adjacent segments, including S4-5
I, S4-5
II, S5
II, and all S6 segments. Our studies provide important insight into the electromechanical coupling mechanism of the single-chain voltage-gated ion channels and afford molecular interpretations for a number of pain-associated mutations whose pathogenic mechanism cannot be revealed from previously reported Na
v structures.
