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Identification and characterization of hydrophobic gate residues in TRP channels
Author(s) -
Zheng Wang,
Hu Ruikun,
Cai Ruiqi,
Hofmann Laura,
Hu Qiaolin,
Fatehi Mohammad,
Long Wentong,
Kong Tim,
Tang Jingfeng,
Light Peter,
Flockerzi Veit,
Cao Ying,
Chen XingZhen
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.201700599rr
Subject(s) - chemistry , biophysics , gating , xenopus , transient receptor potential channel , hydrophobic effect , residue (chemistry) , stereochemistry , crystallography , biochemistry , receptor , biology , gene
Transient receptor potential (TRP) channels, subdivided into 6 subfamilies in mammals, have essential roles in sensory physiology. They respond to remarkably diverse stimuli, comprising thermal, chemical, and mechanical modalities, through opening or closing of channel gates. In this study, we systematically substituted the hydrophobic residues within the distal fragment of pore‐lining helix S6 with hydrophilic residues and, based on Xenopus oocyte and mammalian cell electrophysiology and a hydrophobic gate theory, identified hydrophobic gates in TRPV6/V5/V4/C4/ M8. We found that channel activity drastically increased when TRPV6 Ala616 or Met617 or TRPV5 Ala576 or Met577 , but not any of their adjacent residues, was substituted with hydrophilic residues. Channel activity strongly correlated with the hydrophilicity of the residues at those sites, suggesting that consecutive hydrophobic residues TRPV6 Ala616‐Met617 and TRPV5 Ala576‐Met577 form a double‐residue gate in each channel. By the same strategy, we identified a hydrophobic single‐residue gate in TRPV4 Iso715 , TRPC4 Iso617 , and TRPM8 Val976 . In support of the hydrophobic gate theory, hydrophilic substitution at the gate site, which removes the hydrophobic gate seal, substantially increased the activity of TRP channels in low‐activity states but had little effect on the function of activated channels. The double‐residue gate channels were more sensitive to small changes in the gate's hydrophobicity or size than single‐residue gate channels. The unconventional double‐reside gating mechanism in TRP channels may have been evolved to respond especially to physiologic stimuli that trigger relatively small gate conformational changes.—Zheng, W., Hu, R., Cai, R., Hofmann, L., Hu, Q., Fatehi, M., Long, W., Kong, T., Tang, J., Light, P., Flockerzi, V., Cao, Y., Chen, X.‐Z. Identification and characterization of hydrophobic gate residues in TRP channels. FASEB J. 32, 639–653 (2018). www.fasebj.org