A conserved glutamate is important for slow inactivation in K+ channels

Neuron. 2000 Sep;27(3):573-83. doi: 10.1016/s0896-6273(00)00067-2.

Abstract

Voltage-gated ion channels undergo slow inactivation during prolonged depolarizations. We investigated the role of a conserved glutamate at the extracellular end of segment 5 (S5) in slow inactivation by mutating it to a cysteine (E418C in Shaker). We could lock the channel in two different conformations by disulfide-linking 418C to two different cysteines, introduced in the Pore-S6 (P-S6) loop. Our results suggest that E418 is normally stabilizing the open conformation of the slow inactivation gate by forming hydrogen bonds with the P-S6 loop. Breaking these bonds allows the P-S6 loop to rotate, which closes the slow inactivation gate. Our results also suggest a mechanism of how the movement of the voltage sensor can induce slow inactivation by destabilizing these bonds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence / genetics
  • Amino Acid Substitution
  • Animals
  • Barium / pharmacology
  • Conserved Sequence / genetics*
  • Disulfides / chemistry
  • Glutamic Acid / genetics*
  • Hydrogen Bonding
  • Hydrogen Peroxide / pharmacology
  • Ion Channel Gating / drug effects
  • Ion Channel Gating / genetics
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Oocytes / cytology
  • Oocytes / metabolism
  • Patch-Clamp Techniques
  • Phenanthrolines / pharmacology
  • Potassium Channels / chemistry
  • Potassium Channels / genetics*
  • Potassium Channels / metabolism*
  • Protein Conformation / drug effects
  • Reducing Agents / pharmacology
  • Structure-Activity Relationship
  • Transfection
  • Xenopus

Substances

  • Disulfides
  • Phenanthrolines
  • Potassium Channels
  • Reducing Agents
  • Barium
  • Glutamic Acid
  • Hydrogen Peroxide
  • 1,10-phenanthroline