Tuning the voltage-sensor motion with a single residue

Biophys J. 2012 Aug 8;103(3):L23-L25. doi: 10.1016/j.bpj.2012.06.030.


The Ciona intestinalis voltage-sensitive phosphatase (Ci-VSP) represents the first discovered member of enzymes regulated by a voltage-sensor domain (VSD) related to the VSD found in voltage-gated ion channels. Although the VSD operation in Ci-VSP exhibits original voltage dependence and kinetics compared to ion channels, it has been poorly investigated. Here, we show that the kinetics and voltage dependence of VSD movement in Ci-VSP can be tuned over 2 orders of magnitude and shifted over 120 mV, respectively, by the size of a conserved isoleucine (I126) in the S1 segment, thus indicating the importance of this residue in Ci-VSP activation. Mutations of the conserved Phe in the S2 segment (F161) do not significantly perturb the voltage dependence of the VSD movement, suggesting a unique voltage sensing mechanism in Ci-VSP.

Publication types

  • Letter
  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Cell Membrane / metabolism
  • Conserved Sequence
  • Electric Conductivity
  • Hydrophobic and Hydrophilic Interactions
  • Isoleucine
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • Movement*
  • Phosphoric Monoester Hydrolases / chemistry*
  • Phosphoric Monoester Hydrolases / metabolism*
  • Protein Structure, Secondary


  • Isoleucine
  • voltage-sensor-containing phosphatase, Ciona intestinalis
  • Phosphoric Monoester Hydrolases