TY - JOUR T1 - Human mutations highlight an intersubunit cation–π bond that stabilizes the closed but not open or inactivated states of TRPV channels JF - Proceedings of the National Academy of Sciences JO - Proc Natl Acad Sci USA SP - 9410 LP - 9416 DO - 10.1073/pnas.1820673116 VL - 116 IS - 19 AU - Teng, Jinfeng AU - Anishkin, Andriy AU - Kung, Ching AU - Blount, Paul Y1 - 2019/05/07 UR - http://www.pnas.org/content/116/19/9410.abstract N2 - Transient receptor potential (TRP) channels are key cation channels that respond to thermal, chemical, electric, or mechanical stimuli. There are &gt;60 mutations known in TrpV4 that cause defects in bone or neural development. Two mutations guided us to examine a cation–π bond, which we found to tie the four subunits together to help close the channel gate. This or a similar bond is seen in many structures of TRP channels. In experiments, breaking this bond favors opening and inactivation of TRPV4.An adequate response of a living cell to the ever-changing environment requires integration of numerous sensory inputs. In many cases, it can be achieved even at the level of a single receptor molecule. Polymodal transient receptor potential (TRP) channels have been shown to integrate mechanical, chemical, electric, and thermal stimuli. Inappropriate gating can lead to pathologies. Among the &gt;60 known TRP vanilloid subfamily (V) 4 mutations that interfere with bone development are Y602C or R616Q at the S4–S5 linker. A cation–π bond between the conservative residues Y602 and R616 of neighboring subunits appears likely in many homologous channel structures in a closed state. Our experiments with TRPV4 mutants indicate that the resting-closed state remains stable while the bond is substituted by a salt bridge or disulfide bond, whereas disruption of the contact by mutations like Y602C or R616Q produces gain-of-function phenotypes when TRPV4 is heterologously expressed in the Xenopus oocyte or yeast. Our data indicate that the Y602–R616 cation–π interactions link the four S4–S5 linker helices together, forming a girdle backing the closed gate. Analogous cation–π bonds and the girdle are seen in many closed TRP channel structures. This girdle is not observed in the cryo-EM structure of amphibian TRPV4 (Protein Data Bank ID code 6BBJ), which appears to be in a different impermeable state—we hypothesize this is the inactivated state. ER -