Vanilloid agonist-mediated activation of TRPV1 channels requires coordinated movement of the S1–S4 bundle rather than a quiescent state

Transient receptor potential vanilloid 1(TRPV1)channel plays an important role in a wide range of physiological and pathological processes,and a comprehensive understanding of TRPV1 gating will create opportunities for therapeutic intervention.Recent incredible advances in cryo-electron microscopy(cryo-EM)have yielded high-resolution structures of all TRPV subtypes(TRPV1-6)and all of them share highly conserved six transmembrane(TM)domains(S1-S6).As revealed by the open structures of TRPV1 in the presence of a bound vanilloid agonist(capsaicin or resiniferatoxin),TM helices S1 to S4 form a bundle that remains quiescent during channel activation,highlighting differences in the gating mechanism of TRPV1 and voltage-gated ion channels.Here,however,we argue that the structural dynamics rather than quiescence of S1-S4 domains is necessary for capsaicin-mediated activation of TRPV1.Using fluorescent unnatural amino acid(flUAA)incorporation and voltage-clamp fluorometry(VCF)analysis,we directly observed allostery of the S1-S4 bundle upon capsaicin binding.Covalent occupation of VCF-identified sites,single-channel recording,cell apoptosis analysis,and exploration of the role of PSFL828,a novel non-vanilloid agonist we identified,have collectively confirmed the essential role of this coordinated S1-S4 motility in capsaicin-mediated activation of TRPV1.This study concludes that,in contrast to cryo-EM structural studies,vanilloid agonists are also required for S1-S4 movement during TRPV1 activation.Redefining the gating process of vanilloid agonists and the discovery of new non-vanilloid agonists will allow the evaluation of new strategies aimed at the development of TRPV1 modulators.