Functional mutagenesis screens reveal the 'cap structure' formation in disulfide-bridge free TASK channels

Matthias Goldstein; Susanne Rinné; Aytug K Kiper; David Ramírez; Michael F Netter; Daniel Bustos; Beatriz Ortiz-Bonnin; Wendy González; Niels Decher

doi:10.1038/srep19492

Functional mutagenesis screens reveal the 'cap structure' formation in disulfide-bridge free TASK channels

Sci Rep. 2016 Jan 22:6:19492. doi: 10.1038/srep19492.

Authors

Matthias Goldstein¹, Susanne Rinné¹, Aytug K Kiper¹, David Ramírez², Michael F Netter¹, Daniel Bustos², Beatriz Ortiz-Bonnin¹, Wendy González², Niels Decher¹

Affiliations

¹ Institute for Physiology and Pathophysiology, University of Marburg, 35037 Marburg, Germany.
² Center for Bioinformatics and Molecular Simulation, University of Talca, Talca, Chile.

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Alanine / genetics
Amino Acid Sequence
Animals
Cell Membrane / metabolism
Conserved Sequence
Cysteine / metabolism
Disulfides / metabolism*
Electric Conductivity
Genetic Testing*
Glycosylation
Humans
Hydrophobic and Hydrophilic Interactions
Models, Molecular
Mutagenesis / genetics*
Mutant Proteins / chemistry
Mutant Proteins / metabolism
Mutation / genetics
Nerve Tissue Proteins / chemistry*
Nerve Tissue Proteins / genetics*
Nerve Tissue Proteins / metabolism
Potassium Channels / chemistry*
Potassium Channels / genetics*
Potassium Channels / metabolism
Potassium Channels, Tandem Pore Domain / chemistry*
Potassium Channels, Tandem Pore Domain / genetics*
Potassium Channels, Tandem Pore Domain / metabolism
Protein Binding
Protein Domains
Protein Multimerization
Protein Subunits / chemistry
Protein Subunits / metabolism
Xenopus

Substances

Disulfides
KCNK4 protein, human
Mutant Proteins
Nerve Tissue Proteins
Potassium Channels
Potassium Channels, Tandem Pore Domain
Protein Subunits
potassium channel subfamily K member 3
Cysteine
Alanine