Coupling between the voltage-sensing and phosphatase domains of Ci-VSP
| Autor: | Francisco Bezanilla, Carlos A. Villalba-Galea, Maurizio Taglialatela, Francesco Miceli |
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| Přispěvatelé: | Villalba Galea, Carlos A., Miceli, Francesco, Taglialatela, Maurizio, Bezanilla, Francisco |
| Rok vydání: | 2009 |
| Předmět: |
Oocyte
Physiology Phosphatase Xenopus laevi Phosphatase binding DUSP6 Phosphoric Monoester Hydrolase Arginine Membrane Potential Article Membrane Potentials Structure-Activity Relationship Xenopus laevis 03 medical and health sciences Enzyme activator 0302 clinical medicine Protein structure Animals Tensin PTEN Cells Cultured 030304 developmental biology Kinetic 0303 health sciences Binding Sites biology Animal Binding Site PTEN Phosphohydrolase Protein phosphatase 2 Phosphoric Monoester Hydrolases Protein Structure Tertiary Enzyme Activation Kinetics Biochemistry Oocytes Commentary biology.protein Ion Channel Gating 030217 neurology & neurosurgery Protein Binding |
| Zdroj: | The Journal of General Physiology |
| ISSN: | 1540-7748 0022-1295 |
| DOI: | 10.1085/jgp.200910215 |
| Popis: | The Ciona intestinalis voltage sensor–containing phosphatase (Ci-VSP) shares high homology with the phosphatidylinositol phosphatase enzyme known as PTEN (phosphatase and tensin homologue deleted on chromosome 10). We have taken advantage of the similarity between these proteins to inquire about the coupling between the voltage sensing and the phosphatase domains in Ci-VSP. Recently, it was shown that four basic residues (R11, K13, R14, and R15) in PTEN are critical for its binding onto the membrane, required for its catalytic activity. Ci-VSP has three of the basic residues of PTEN. Here, we show that when R253 and R254 (which are the homologues of R14 and R15 in PTEN) are mutated to alanines in Ci-VSP, phosphatase activity is disrupted, as revealed by a lack of effect on the ionic currents of KCNQ2/3, where current decrease is a measure of phosphatase activity. The enzymatic activity was not rescued by the introduction of lysines, indicating that the binding is an arginine-specific interaction between the phosphatase binding domain and the membrane, presumably through the phosphate groups of the phospholipids. We also found that the kinetics and steady-state voltage dependence of the S4 segment movement are affected when the arginines are not present, indicating that the interaction of R253 and R254 with the membrane, required for the catalytic action of the phosphatase, restricts the movement of the voltage sensor. |
| Databáze: | OpenAIRE |
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