title: Functional mutagenesis screens reveal the 'cap structure' formation in disulfide-bridge free TASK channels.
abstract: Two-pore-domain potassium (K2P) channels have a large extracellular cap structure formed by two M1-P1 linkers, containing a cysteine for dimerization. However, this cysteine is not present in the TASK-1/3/5 subfamily. The functional role of the cap is poorly understood and it remained unclear whether K2P channels assemble in the domain-swapped orientation or not. Functional alanine-mutagenesis screens of TASK-1 and TRAAK were used to build an in silico model of the TASK-1 cap. According to our data the cap structure of disulfide-bridge free TASK channels is similar to that of other K2P channels and is most likely assembled in the domain-swapped orientation. As the conserved cysteine is not essential for functional expression of all K2P channels tested, we propose that hydrophobic residues at the inner leaflets of the cap domains can interact with each other and that this way of stabilizing the cap is most likely conserved among K2P channels.
authors.affiliation: Institute for Physiology and Pathophysiology, University of Marburg, 35037 Marburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Goldstein
authors.affiliation: Institute for Physiology and Pathophysiology, University of Marburg, 35037 Marburg, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Rinné
authors.affiliation: Institute for Physiology and Pathophysiology, University of Marburg, 35037 Marburg, Germany.
authors.forename: Aytug K
authors.initials: AK
authors.lastname: Kiper
authors.affiliation: Center for Bioinformatics and Molecular Simulation, University of Talca, Talca, Chile.
authors.forename: David
authors.initials: D
authors.lastname: Ramírez
authors.affiliation: Institute for Physiology and Pathophysiology, University of Marburg, 35037 Marburg, Germany.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Netter
authors.affiliation: Center for Bioinformatics and Molecular Simulation, University of Talca, Talca, Chile.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bustos
authors.affiliation: Institute for Physiology and Pathophysiology, University of Marburg, 35037 Marburg, Germany.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Ortiz-Bonnin
authors.affiliation: Center for Bioinformatics and Molecular Simulation, University of Talca, Talca, Chile.
authors.forename: Wendy
authors.initials: W
authors.lastname: González
authors.affiliation: Institute for Physiology and Pathophysiology, University of Marburg, 35037 Marburg, Germany.
authors.forename: Niels
authors.initials: N
authors.lastname: Decher
mesh_terms: D000409:Alanine / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D017124:Conserved Sequence; D003545:Cysteine / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism*; D004553:Electric Conductivity; D005820:Genetic Testing; D006031:Glycosylation; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D016296:Mutagenesis / Q000235:genetics*; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D024683:Potassium Channels, Tandem Pore Domain / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D000072417:Protein Domains; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D014981:Xenopus
chemical_list: D004220:Disulfides; C503432:KCNK4 protein, human; D050505:Mutant Proteins; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D021122:Protein Subunits; C420132:potassium channel subfamily K member 3; D003545:Cysteine; D000409:Alanine