Reinterpretation of the substrate specificity of the voltage-sensing phosphatase during dimerization

Voltage-sensing phosphatases (VSPs) cleave both 3- and 5-phosphates from inositol phospholipids in response to membrane depolarization. When low concentrations of VSP are expressed in oocytes, the 5-phosphatase reaction can be observed during large membrane depolarizations. When higher concentration...

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Bibliographic Details
Published in:The Journal of general physiology Vol. 151; no. 2; p. 258
Main Authors: Kruse, Martin, Kohout, Susy C, Hille, Bertil
Format: Journal Article
Language:English
Published: United States 04.02.2019
Subjects:
Animals
Humans
Membrane Potentials
Phosphoric Monoester Hydrolases - chemistry
Phosphoric Monoester Hydrolases - metabolism
Protein Multimerization
Substrate Specificity
Xenopus
ISSN:1540-7748, 1540-7748
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Summary:Voltage-sensing phosphatases (VSPs) cleave both 3- and 5-phosphates from inositol phospholipids in response to membrane depolarization. When low concentrations of VSP are expressed in 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.
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ISSN:1540-7748
1540-7748
DOI:10.1085/jgp.201812260