title: Molecular insights into lipid-assisted Ca2+regulation of the TRP channel Polycystin-2.
abstract: Polycystin-2 (PC2), a calcium-activated cation TRP channel, is involved in diverse Ca2+signaling pathways. Malfunctioning Ca2+regulation in PC2 causes autosomal-dominant polycystic kidney disease. Here we report two cryo-EM structures of distinct channel states of full-length human PC2 in complex with lipids and cations. The structures reveal conformational differences in the selectivity filter and in the large exoplasmic domain (TOP domain), which displays differing N-glycosylation. The more open structure has one cation bound below the selectivity filter (single-ion mode, PC2SI), whereas multiple cations are bound along the translocation pathway in the second structure (multi-ion mode, PC2MI). Ca2+binding at the entrance of the selectivity filter suggests Ca2+blockage in PC2MI, and we observed density for the Ca2+-sensing C-terminal EF hand in the unblocked PC2SIstate. The states show altered interactions of lipids with the pore loop and TOP domain, thus reflecting the functional diversity of PC2 at different locations, owing to different membrane compositions.
authors.affiliation: Max Planck Institute of Biophysics, Department of Structural Biology, Frankfurt, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Wilkes
authors.affiliation: Biophysics II, Faculty of Biology and Preclinical Medicine, Regensburg, Germany.
authors.forename: M Gregor
authors.identifier: 0000-0001-9181-6387
authors.initials: MG
authors.lastname: Madej
authors.affiliation: Biophysics II, Faculty of Biology and Preclinical Medicine, Regensburg, Germany.
authors.forename: Lydia
authors.initials: L
authors.lastname: Kreuter
authors.affiliation: Max Planck Institute of Biophysics, Department of Structural Biology, Frankfurt, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rhinow
authors.affiliation: Biophysics II, Faculty of Biology and Preclinical Medicine, Regensburg, Germany.
authors.forename: Veronika
authors.initials: V
authors.lastname: Heinz
authors.affiliation: Biophysics II, Faculty of Biology and Preclinical Medicine, Regensburg, Germany.
authors.forename: Silvia
authors.initials: S
authors.lastname: De Sanctis
authors.affiliation: Biophysics II, Faculty of Biology and Preclinical Medicine, Regensburg, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Ruppel
authors.affiliation: Biophysics II, Faculty of Biology and Preclinical Medicine, Regensburg, Germany.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Richter
authors.affiliation: Max Planck Institute of Biophysics, Department of Structural Biology, Frankfurt, Germany.
authors.forename: Friederike
authors.initials: F
authors.lastname: Joos
authors.affiliation: Structural Genomics Consortium, University of Oxford, Oxford, UK.
authors.forename: Marina
authors.initials: M
authors.lastname: Grieben
authors.affiliation: Structural Genomics Consortium, University of Oxford, Oxford, UK.
authors.forename: Ashley C W
authors.identifier: 0000-0001-9661-2607
authors.initials: AC
authors.lastname: Pike
authors.affiliation: Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
authors.forename: Juha T
authors.identifier: 0000-0002-0348-7323
authors.initials: JT
authors.lastname: Huiskonen
authors.affiliation: Structural Genomics Consortium, University of Oxford, Oxford, UK.
authors.forename: Elisabeth P
authors.identifier: 0000-0001-9138-2937
authors.initials: EP
authors.lastname: Carpenter
authors.affiliation: Max Planck Institute of Biophysics, Department of Structural Biology, Frankfurt, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Kühlbrandt
authors.affiliation: Department of Anatomy, Faculty of Biology and Preclinical Medicine, Regensburg, Germany.
authors.forename: Ralph
authors.initials: R
authors.lastname: Witzgall
authors.affiliation: Biophysics II, Faculty of Biology and Preclinical Medicine, Regensburg, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Ziegler
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000737:chemistry; D020013:Calcium Signaling; D020285:Cryoelectron Microscopy; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D010712:Phosphatidic Acids / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072417:Protein Domains; D011499:Protein Processing, Post-Translational; D020836:Protein Structure, Quaternary; D050396:TRPP Cation Channels / Q000737:chemistry*
chemical_list: D002118:Calcium; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D050396:TRPP Cation Channels