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XB-ART-55898
Proc Natl Acad Sci U S A 2019 May 07;11619:9410-9416. doi: 10.1073/pnas.1820673116.
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Human mutations highlight an intersubunit cation-π bond that stabilizes the closed but not open or inactivated states of TRPV channels.

Teng J , Anishkin A , Kung C , Blount P .


Abstract
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 >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.

PubMed ID: 31010928
PMC ID: PMC6511060
Article link: Proc Natl Acad Sci U S A
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: trpv4

References [+] :
Bavi, The role of MscL amphipathic N terminus indicates a blueprint for bilayer-mediated gating of mechanosensitive channels. 2016, Pubmed