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.

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