title: Noncompetitive inhibition of plant protein Ser/Thr phosphatase PP7 by phosphate.
abstract: 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.
authors.affiliation: Research School of Biological and Molecular Sciences, Oxford Brookes University, Oxford, Headington, OX3 0BP, United Kingdom.
authors.forename: M A
authors.initials: MA
authors.lastname: Kutuzov
authors.forename: A V
authors.initials: AV
authors.lastname: Andreeva
mesh_terms: 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
chemical_list: D002614:Chelating Agents; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D010710:Phosphates; D010940:Plant Proteins; D011994:Recombinant Proteins; D019163:Reducing Agents; C008644:nitrophenylphosphate; D010749:Phosphoprotein Phosphatases