title: Selective disruption of high sensitivity heat activation but not capsaicin activation of TRPV1 channels by pore turret mutations.
abstract: The capsaicin receptor transient receptor potential vanilloid (TRPV)1 is a highly heat-sensitive ion channel. Although chemical activation and heat activation of TRPV1 elicit similar pungent, painful sensation, the molecular mechanism underlying synergistic activation remains mysterious. In particular, where the temperature sensor is located and whether heat and capsaicin share a common activation pathway are debated. To address these fundamental issues, we searched for channel mutations that selectively affected one form of activation. We found that deletion of the first 10 amino acids of the pore turret significantly reduced the heat response amplitude and shifted the heat activation threshold, whereas capsaicin activation remained unchanged. Removing larger portions of the turret disrupted channel function. Introducing an artificial sequence to replace the deleted region restored sensitive capsaicin activation in these nonfunctional channels. The heat activation, however, remained significantly impaired, with the current exhibiting diminishing heat sensitivity to a level indistinguishable from that of a voltage-gated potassium channel, Kv7.4. Our results demonstrate that heat and capsaicin activation of TRPV1 are structurally and mechanistically distinct processes, and the pore turret is an indispensible channel structure involved in the heat activation process but is not part of the capsaicin activation pathway. Synergistic effect of heat and capsaicin on TRPV1 activation may originate from convergence of the two pathways on a common activation gate.
authors.affiliation: Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA 95616, USA.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Cui
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.forename: Xu
authors.initials: X
authors.lastname: Cao
authors.forename: Vladimir
authors.initials: V
authors.lastname: Yarov-Yarovoy
authors.forename: KeWei
authors.initials: K
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Zheng
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D057809:HEK293 Cells; D006358:Hot Temperature; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D040542:Mechanotransduction, Cellular / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D016062:Porosity / Q000187:drug effects; D013329:Structure-Activity Relationship; D050916:TRPV Cation Channels / Q000235:genetics* / Q000378:metabolism*
chemical_list: D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; D002211:Capsaicin