Abstract
Capsaicin bestows spiciness by activating TRPV1 channel with exquisite potency and selectivity. Although a capsaicin-bound channel structure was previously resolved by cryo-EM at 4.2- to 4.5-Å resolution, capsaicin was registered as a small electron density, reflecting neither its chemical structure nor specific ligand-channel interactions--important details required for mechanistic understanding. We obtained the missing atomic-level details by iterative computation and confirmed them by systematic site-specific functional tests. We observed that the bound capsaicin takes a 'tail-up, head-down' configuration. The vanillyl and amide groups form specific interactions to anchor its bound position, while the aliphatic tail may sample a range of conformations, making it invisible in cryo-EM images. Capsaicin stabilizes TRPV1's open state by 'pull-and-contact' interactions between the vanillyl group and the S4-S5 linker. Our study provides a structural mechanism for the agonistic function of capsaicin and its analogs, and demonstrates an effective approach to obtain atomic-level information from cryo-EM structures.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Amino Acid Sequence
-
Animals
-
Bacterial Proteins / chemistry
-
Bacterial Proteins / genetics
-
Capsaicin / chemistry*
-
Chickens
-
Cryoelectron Microscopy
-
Gene Expression
-
HEK293 Cells
-
Humans
-
Ion Channel Gating
-
Kinetics
-
Luminescent Proteins / chemistry
-
Luminescent Proteins / genetics
-
Mice
-
Molecular Docking Simulation
-
Molecular Sequence Data
-
Patch-Clamp Techniques
-
Point Mutation
-
Protein Binding
-
Rabbits
-
Rats
-
Recombinant Fusion Proteins / chemistry
-
Recombinant Fusion Proteins / genetics
-
Sequence Alignment
-
Sequence Homology, Amino Acid
-
Species Specificity
-
TRPV Cation Channels / agonists*
-
TRPV Cation Channels / chemistry*
-
TRPV Cation Channels / genetics
Substances
-
Bacterial Proteins
-
Luminescent Proteins
-
Recombinant Fusion Proteins
-
TRPV Cation Channels
-
TRPV1 protein, mouse
-
yellow fluorescent protein, Bacteria
-
Capsaicin
Associated data
-
PubChem-Substance/251855291
-
PubChem-Substance/251855292
-
PubChem-Substance/251855293
-
PubChem-Substance/251855294
-
PubChem-Substance/251855295
-
PubChem-Substance/251855296
-
PubChem-Substance/251855297
-
PubChem-Substance/251855298
-
PubChem-Substance/251855299