Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
J Gen Physiol
2019 Feb 04;1512:258-263. doi: 10.1085/jgp.201812260.
Show Gene links
Show Anatomy links
Reinterpretation of the substrate specificity of the voltage-sensing phosphatase during dimerization.
Kruse M
,
Kohout SC
,
Hille B
.
???displayArticle.abstract???
Voltage-sensing phosphatases (VSPs) cleave both 3- and 5-phosphates from inositol phospholipids in response to membrane depolarization. When low concentrations of Ciona intestinalis VSP are expressed in Xenopus laevis oocytes, the 5-phosphatase reaction can be observed during large membrane depolarizations. When higher concentrations are expressed, the 5-phosphatase activity is observed with smaller depolarizations, and the 3-phosphatase activity is revealed with strong depolarization. Here we ask whether this apparent induction of 3-phosphatase activity is attributable to the dimerization that has been reported when VSP is expressed at higher concentrations. Using a simple kinetic model, we show that these enzymatic phenomena can be understood as an emergent property of a voltage-dependent enzyme with invariant substrate selectivity operating in the context of endogenous lipid-metabolizing enzymes present in oocytes. Thus, a switch of substrate specificity with dimerization need not be invoked to explain the appearance of 3-phosphatase activity at high VSP concentrations.
???displayArticle.pubmedLink???
30622132
???displayArticle.pmcLink???PMC6363406 ???displayArticle.link???J Gen Physiol ???displayArticle.grants???[+]
P41 GM103313 NIGMS NIH HHS , R37 NS008174 NINDS NIH HHS , P20 GM103423 NIGMS NIH HHS , P20 GM103423 National Institute of General Medical Sciences, P41 GM103313 National Institute of General Medical Sciences, R01 GM111685 National Institute of General Medical Sciences, R37 NS008174 National Institute of Neurological Disorders and Stroke, R01 GM111685 NIGMS NIH HHS
Figure 1. Reaction scheme of the
Keum et al. (2016)
model. Background endogenous kinase and phosphatase reactions in black arrows, and four phosphatase reactions catalyzed by VSP in red arrows. Fig. 2 concerns changes in PI(3,4)P2 as measured by the fTAPP-1 indicator.
Figure 2. Comparison of observed and modeled voltage dependence of fTAPP FRET with different expression levels of Ci-VSP in Xenopus oocytes. (A) Reaction schematic of fTAPP assay where the fTAPP-1-PH FRET sensor shows an increase in FRET when PI(3,4)P2 is produced and a decrease in FRET when PI(3,4)P2 is depleted. (B) Normalized change of fTAPP-1 FRET (ÎFRET/FRETfTAPP-1) versus voltage relationships for six different cRNA injection amounts: 1 ng (light blue), 2.5 ng (blue), 5 ng (yellow), 10 ng (orange), 40 ng (gray), and 80 ng (black). A dashed vertical line is drawn at +56 mV. At high levels of Ci-VSP expression (40 and 80 ng cRNA injections), a FRET increase is observed with small depolarizations, changing to a FRET decrease with the largest depolarizations. At lower levels of Ci-VSP expression (1â5 ng cRNA injections), the FRET increase shifts to higher depolarizations and the FRET decrease is no longer detectable. Error bars are ±SEM, n ⥠11. Data are from Rayaprolu et al., 2018. (C and D) Simulations of curves in B using two models derived from Keum et al. (2016) as described in the text and Table 1. (C) Calculations using Boltzmann parameters taken from sensing-current measurements on Ci-VSP expressed in oocytes (V0.5 = 57 mV, z = 1.56 electronic charges; Villalba-Galea et al., 2013). (D) Calculations with revised Boltzmann parameters: V0.5 = 95 mV and z = 1.40 electronic charges. Simulations were done with Virtual Cell (http://www.nrcam.uchc.edu; University of Connecticut Health Center).
Campbell,
Allosteric activation of PTEN phosphatase by phosphatidylinositol 4,5-bisphosphate.
2003, Pubmed
Campbell,
Allosteric activation of PTEN phosphatase by phosphatidylinositol 4,5-bisphosphate.
2003,
Pubmed
Dowler,
Identification of pleckstrin-homology-domain-containing proteins with novel phosphoinositide-binding specificities.
2000,
Pubmed
Falkenburger,
Kinetics of PIP2 metabolism and KCNQ2/3 channel regulation studied with a voltage-sensitive phosphatase in living cells.
2010,
Pubmed
Grimm,
Allosteric substrate switching in a voltage-sensing lipid phosphatase.
2016,
Pubmed
,
Xenbase
Halaszovich,
Ci-VSP is a depolarization-activated phosphatidylinositol-4,5-bisphosphate and phosphatidylinositol-3,4,5-trisphosphate 5'-phosphatase.
2009,
Pubmed
Iwasaki,
A voltage-sensing phosphatase, Ci-VSP, which shares sequence identity with PTEN, dephosphorylates phosphatidylinositol 4,5-bisphosphate.
2008,
Pubmed
,
Xenbase
Kawanabe,
The hydrophobic nature of a novel membrane interface regulates the enzyme activity of a voltage-sensing phosphatase.
2018,
Pubmed
Keum,
Phosphoinositide 5- and 3-phosphatase activities of a voltage-sensing phosphatase in living cells show identical voltage dependence.
2016,
Pubmed
Kohout,
Subunit organization and functional transitions in Ci-VSP.
2008,
Pubmed
Kohout,
Electrochemical coupling in the voltage-dependent phosphatase Ci-VSP.
2010,
Pubmed
Kurokawa,
3' Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] by voltage-sensing phosphatase (VSP).
2012,
Pubmed
Liu,
A glutamate switch controls voltage-sensitive phosphatase function.
2012,
Pubmed
Murata,
Phosphoinositide phosphatase activity coupled to an intrinsic voltage sensor.
2005,
Pubmed
,
Xenbase
Murata,
Depolarization activates the phosphoinositide phosphatase Ci-VSP, as detected in Xenopus oocytes coexpressing sensors of PIP2.
2007,
Pubmed
,
Xenbase
Okamura,
Voltage-Sensing Phosphatases: Biophysics, Physiology, and Molecular Engineering.
2018,
Pubmed
Rayaprolu,
Dimerization of the voltage-sensing phosphatase controls its voltage-sensing and catalytic activity.
2018,
Pubmed
,
Xenbase
Sakata,
Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid.
2016,
Pubmed
,
Xenbase
Villalba-Galea,
S4-based voltage sensors have three major conformations.
2008,
Pubmed
Villalba-Galea,
Sensing charges of the Ciona intestinalis voltage-sensing phosphatase.
2013,
Pubmed
Xu,
Kinetic analysis of receptor-activated phosphoinositide turnover.
2003,
Pubmed
