Noncompetitive inhibition of plant protein Ser/Thr phosphatase PP7 by phosphate.
Changes in the cytoplasmic inorganic phosphate (P(i)) concentrations are an important cue for the plant cells to regulate their metabolism and phosphate homeostasis. However, phosphate sensors/receptors involved in this regulation are largely unknown. P(i) is a common nonspecific competitive inhibitor of phosphatases, usually in millimolar range. Here we report a procedure to refold recombinant Arabidopsis thaliana protein Ser/Thr phosphatase PP7 and demonstrate that PP7 is inhibited by submillimolar P(i) concentrations (IC(50) = 0.66 +/- 0.14 mM) via a mainly noncompetitive mechanism. The results indicate that PP7 may possess a specific P(i)-binding site responsible for its allosteric regulation, and suggest a possible phosphate sensor function for this protein phosphatase.
Kutuzov
M A
MA
Research School of Biological and Molecular Sciences, Oxford Brookes University, Oxford, Headington, OX3 0BP, United Kingdom.
Andreeva
A V
AV
D000494:Allosteric Regulation / Q000187:drug effects; D017360:Arabidopsis; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000235:genetics; D002479:Inclusion Bodies / Q000201:enzymology; D009596:Nitrophenols / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019163:Reducing Agents / Q000494:pharmacology
D002614:Chelating Agents; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D010710:Phosphates; D010940:Plant Proteins; D011994:Recombinant Proteins; D019163:Reducing Agents; C008644:nitrophenylphosphate; D010749:Phosphoprotein Phosphatases