title: A Gate Hinge Controls the Epithelial Calcium Channel TRPV5.
abstract: TRPV5 is unique within the large TRP channel family for displaying a high Ca2+selectivity together with Ca2+-dependent inactivation. Our study aims to uncover novel insights into channel gating through in-depth structure-function analysis. We identify an exceptional tryptophan (W583) at the terminus of the intracellular pore that is unique for TRPV5 (and TRPV6). A combination of site-directed mutagenesis, biochemical and electrophysiological analysis, together with homology modeling, demonstrates that W583 is part of the gate for Ca2+permeation. The W583 mutants show increased cell death due to profoundly enhanced Ca2+influx, resulting from altered channel function. A glycine residue above W583 might act as flexible linker to rearrange the tryptophan gate. Furthermore, we hypothesize functional crosstalk between the pore region and carboxy terminus, involved in Ca2+-calmodulin-mediated inactivation. This study proposes a unique channel gating mechanism and delivers detailed molecular insight into the Ca2+permeation pathway that can be extrapolated to other Ca2+-selective channels.
authors.affiliation: Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors.forename: Jenny
authors.initials: J
authors.lastname: van der Wijst
authors.affiliation: Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Leunissen
authors.affiliation: Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors.forename: Maxime G
authors.initials: MG
authors.lastname: Blanchard
authors.affiliation: Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors.forename: Hanka
authors.initials: H
authors.lastname: Venselaar
authors.affiliation: Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Verkaart
authors.affiliation: Department of Physiology, University of California, San Francisco, California 94158-2517, USA.
authors.forename: Candice E
authors.initials: CE
authors.lastname: Paulsen
authors.affiliation: Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors.forename: René J
authors.initials: RJ
authors.lastname: Bindels
authors.affiliation: Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.
authors.forename: Joost G
authors.initials: JG
authors.lastname: Hoenderop
mesh_terms: D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008564:Membrane Potentials; D016297:Mutagenesis, Site-Directed; D018408:Patch-Clamp Techniques; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D050916:TRPV Cation Channels; C492239:TRPV5 protein, human; D002118:Calcium