title: Enzyme domain affects the movement of the voltage sensor in ascidian and zebrafish voltage-sensing phosphatases.
abstract: The ascidian voltage-sensing phosphatase (Ci-VSP) consists of the voltage sensor domain (VSD) and a cytoplasmic phosphatase region that has significant homology to the phosphatase and tensin homolog deleted on chromosome TEN (PTEN). The phosphatase activity of Ci-VSP is modified by the conformational change of the VSD. In many proteins, two protein modules are bidirectionally coupled, but it is unknown whether the phosphatase domain could affect the movement of the VSD in VSP. We addressed this issue by whole-cell patch recording of gating currents from a teleost VSP (Dr-VSP) cloned from Danio rerio expressed in tsA201 cells. Replacement of a critical cysteine residue, in the phosphatase active center of Dr-VSP, by serine sharpened both ON- and OFF-gating currents. Similar changes were produced by treatment with phosphatase inhibitors, pervanadate and orthovanadate, that constitutively bind to cysteine in the active catalytic center of phosphatases. The distinct kinetics of gating currents dependent on enzyme activity were not because of altered phosphatidylinositol 4,5-bisphosphate levels, because the kinetics of gating current did not change by depletion of phosphatidylinositol 4,5-bisphosphate, as reported by coexpressed KCNQ2/3 channels. These results indicate that the movement of the VSD is influenced by the enzymatic state of the cytoplasmic domain, providing an important clue for understanding mechanisms of coupling between the VSD and its effector.
authors: Department of Developmental Neurophysiology, Okazaki Institute for Integrative Bioscience, Okazaki, Japan.
authors: Md Israil
authors: MI
authors: Hossain
authors: Hirohide
authors: H
authors: Iwasaki
authors: Yoshifumi
authors: Y
authors: Okochi
authors: Mohamed
authors: M
authors: Chahine
authors: Shinichi
authors: S
authors: Higashijima
authors: Kuniaki
authors: K
authors: Nagayama
authors: Yasushi
authors: Y
authors: Okamura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002642:Chick Embryo; D004594:Electrophysiology / Q000379:methods; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D051381:Rats; D014561:Urochordata; D014981:Xenopus; D015027:Zebrafish
chemical_list: D004791:Enzyme Inhibitors