title: Hydrogen peroxide is a regulator of ABI1, a protein phosphatase 2C from Arabidopsis.
abstract: Protein phosphatases 2C (PP2Cs) exhibit diverse regulatory functions in signalling pathways of animals, yeast and plants. ABI1 is a PP2C of Arabidopsis that exerts negative control on signalling of the phytohormone abscissic acid (ABA). Characterisation of the redox sensitivity of ABI1 revealed a strong enzymatic inactivation by hydrogen peroxide (H2O2) which has recently been implicated as a secondary messenger of ABA signalling. H2O2 reversibly inhibited ABI1 activity in vitro with an IC(50) of approximately 140 microM in the presence of physiological concentrations of glutathione. In addition, ABI1 was highly susceptible to inactivation by phenylarsine oxide (IC(50)=3-4 microM) indicative for the facile oxidation of vicinal cysteine residues. Thus, H2O2 generated during ABA signalling seems to inactivate the negative regulator of the ABA response.
authors.affiliation: Lehrstuhl für Botanik, Technische Universität München, Biologikum Weihenstephan, Am Hochanger 4, 85354, Freising, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Meinhard
authors.forename: E
authors.initials: E
authors.lastname: Grill
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins; D001152:Arsenicals / Q000494:pharmacology; D003545:Cysteine / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D010084:Oxidation-Reduction; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D001152:Arsenicals; D004791:Enzyme Inhibitors; D029701:Saccharomyces cerevisiae Proteins; C029341:oxophenylarsine; D000040:Abscisic Acid; D008715:Methionine; D006861:Hydrogen Peroxide; C087434:ABI1 protein, Arabidopsis; C087358:PTC1 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; D005978:Glutathione; D003545:Cysteine