Identification of molecular determinants of channel gating in the transient receptor potential box of vanilloid receptor I.
Transient receptor potential vanilloid receptor subtype I (TRPV1) is an ion channel gated by physical and chemical stimuli that belongs to the TRPV protein family. TRPV receptors contain a highly conserved, 6-mer segment near the channel gate, known as the TRP box, whose function remains unknown. Here, we performed an alanine scanning mutagenesis of the TRP box of TRPV1 (IWKLQR) and found that mutation of this motif affected channel gating by raising the free energy of channel activation. Functional characterization of TRPV1 mutants showed that substitution of I696, W697, and R701 by alanine severely affected voltage- and heat-dependent activation and notably reduced the capsaicin responsiveness and tachyphylaxia, while mutation of K698, L699, and Q700 had minor effects. In addition, mutation of I696 to alanine promoted a strong outward rectification at negative membrane potentials, and slowed the kinetics of channel activation. Taken together, our findings suggest that modification of I696, W697, and R701 to alanine altered channel function by affecting events downstream of the initial stimuli-sensing step and imply that intersubunit interactions within the TRP box play an important role in TRPV1 gating.
Valente
Pierluigi
P
Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Av. de la Universidad s/n, 03202 Elche, Alicante, Spain.
García-Sanz
Nuria
N
Gomis
Ana
A
Fernández-Carvajal
Asia
A
Fernández-Ballester
Gregorio
G
Viana
Félix
F
Belmonte
Carlos
C
Ferrer-Montiel
Antonio
A
D000595:Amino Acid Sequence; D002211:Capsaicin / Q000494:pharmacology; D002478:Cells, Cultured; D006358:Hot Temperature; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D009154:Mutation; D018408:Patch-Clamp Techniques; D050916:TRPV Cation Channels / Q000737:chemistry* / Q000235:genetics; D013618:Tachyphylaxis / Q000235:genetics; D014162:Transfection
D050916:TRPV Cation Channels; C494482:TRPV1 protein, human; D002211:Capsaicin