title: Tuning the voltage-sensor motion with a single residue.
abstract: 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.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois.
authors.forename: Jérôme J
authors.initials: JJ
authors.lastname: Lacroix
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois. Electronic address: fbezanilla@uchicago.edu.
authors.forename: Francisco
authors.initials: F
authors.lastname: Bezanilla
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000378:metabolism; D017124:Conserved Sequence; D004553:Electric Conductivity; D057927:Hydrophobic and Hydrophilic Interactions; D007532:Isoleucine; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009068:Movement; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry* / Q000378:metabolism*; D017433:Protein Structure, Secondary
chemical_list: D007532:Isoleucine; C509671:voltage-sensor-containing phosphatase, Ciona intestinalis; D010744:Phosphoric Monoester Hydrolases