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Title: Regulation of a plant SNF1-related protein kinase by glucose-6-phosphate

Abstract

One of the major protein kinases (PK{sub III}) that phosphorylates serine-158 of spinach sucrose-phosphate synthase (SPS), which is responsible for light/dark modulation of activity, is known to be a member of the SNF1-related family of protein kinases. In the present study, the authors have developed a fluorescence-based continuous assay for measurement of PK{sub III} activity. Using the continuous assay, along with the fixed-time-point {sup 32}P-incorporation assay, they demonstrate that PK{sub III} activity is inhibited by glucose-6-phosphate (Glc-6-P). Relative inhibition by Glc-6-P was increased by decreasing pH from 8.5 to 5.5 and by reducing the concentration of Mg{sup 2+} in the assay from 10 to 2 nM. Under likely physiological conditions (PH 7.0 and 2 mM Mg{sup 2+}), 10 nM Glc-6-P inhibited kinase activity approximately 70%. Inhibition by Glc-6-P could not be ascribed to contaminants in the commercial preparations. Other metabolites inhibited PK{sub III} in the following order: Glc-6-P > mannose-6-P, fructose-1,6P{sub 2} > ribose-5-P, 3-PGA, fructose-6-P. Inorganic phosphate, Glc, and AMP were not inhibitory, and free Glc did not reverse the inhibition by Glc-6-P. Because SNF1-related protein kinases are thought to function broadly in the regulation of enzyme activity and gene expression, Glc-6-P inhibition of PK{sub III} activity potentially providesmore » a mechanism for metabolic regulation of the reactions catalyzed by these important protein kinases.« less

Authors:
; ;
Publication Date:
Research Org.:
North Carolina State Univ., Raleigh, NC (US)
OSTI Identifier:
20062531
Resource Type:
Journal Article
Journal Name:
Plant Physiology (Bethesda)
Additional Journal Information:
Journal Volume: 123; Journal Issue: 1; Other Information: PBD: May 2000; Journal ID: ISSN 0032-0889
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; PHOSPHOTRANSFERASES; ENZYME ACTIVITY; GENE REGULATION; GLUCOSE; PHOSPHATES; PHOSPHORYLATION; INHIBITION

Citation Formats

Toroser, D., Plaut, Z., and Huber, S.C. Regulation of a plant SNF1-related protein kinase by glucose-6-phosphate. United States: N. p., 2000. Web. doi:10.1104/pp.123.1.403.
Toroser, D., Plaut, Z., & Huber, S.C. Regulation of a plant SNF1-related protein kinase by glucose-6-phosphate. United States. doi:10.1104/pp.123.1.403.
Toroser, D., Plaut, Z., and Huber, S.C. Mon . "Regulation of a plant SNF1-related protein kinase by glucose-6-phosphate". United States. doi:10.1104/pp.123.1.403.
@article{osti_20062531,
title = {Regulation of a plant SNF1-related protein kinase by glucose-6-phosphate},
author = {Toroser, D. and Plaut, Z. and Huber, S.C.},
abstractNote = {One of the major protein kinases (PK{sub III}) that phosphorylates serine-158 of spinach sucrose-phosphate synthase (SPS), which is responsible for light/dark modulation of activity, is known to be a member of the SNF1-related family of protein kinases. In the present study, the authors have developed a fluorescence-based continuous assay for measurement of PK{sub III} activity. Using the continuous assay, along with the fixed-time-point {sup 32}P-incorporation assay, they demonstrate that PK{sub III} activity is inhibited by glucose-6-phosphate (Glc-6-P). Relative inhibition by Glc-6-P was increased by decreasing pH from 8.5 to 5.5 and by reducing the concentration of Mg{sup 2+} in the assay from 10 to 2 nM. Under likely physiological conditions (PH 7.0 and 2 mM Mg{sup 2+}), 10 nM Glc-6-P inhibited kinase activity approximately 70%. Inhibition by Glc-6-P could not be ascribed to contaminants in the commercial preparations. Other metabolites inhibited PK{sub III} in the following order: Glc-6-P > mannose-6-P, fructose-1,6P{sub 2} > ribose-5-P, 3-PGA, fructose-6-P. Inorganic phosphate, Glc, and AMP were not inhibitory, and free Glc did not reverse the inhibition by Glc-6-P. Because SNF1-related protein kinases are thought to function broadly in the regulation of enzyme activity and gene expression, Glc-6-P inhibition of PK{sub III} activity potentially provides a mechanism for metabolic regulation of the reactions catalyzed by these important protein kinases.},
doi = {10.1104/pp.123.1.403},
journal = {Plant Physiology (Bethesda)},
issn = {0032-0889},
number = 1,
volume = 123,
place = {United States},
year = {2000},
month = {5}
}