title: H2O2 inhibits ABA-signaling protein phosphatase HAB1.
abstract: Due to its ability to be rapidly generated and propagated over long distances, H2O2 is an important second messenger for biotic and abiotic stress signaling in plants. In response to low water potential and high salt concentrations sensed in the roots of plants, the stress hormone abscisic acid (ABA) activates NADPH oxidase to generate H2O2, which is propagated in guard cells in leaves to induce stomatal closure and prevent water loss from transpiration. Using a reconstituted system, we demonstrate that H2O2 reversibly prevents the protein phosphatase HAB1, a key component of the core ABA-signaling pathway, from inhibiting its main target in guard cells, SnRK2.6/OST1 kinase. We have identified HAB1 C186 and C274 as H2O2-sensitive thiols and demonstrate that their oxidation inhibits both HAB1 catalytic activity and its ability to physically associate with SnRK2.6 by formation of intermolecular dimers.
authors.affiliation: Laboratories of Structural Sciences/Structural Biology and Biochemistry, Van Andel Research Institute, N.E., Grand Rapids, Michigan, United States of America; Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
authors.forename: Madhuri
authors.initials: M
authors.lastname: Sridharamurthy
authors.affiliation: Laboratories of Structural Sciences/Structural Biology and Biochemistry, Van Andel Research Institute, N.E., Grand Rapids, Michigan, United States of America.
authors.forename: Amanda
authors.initials: A
authors.lastname: Kovach
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47906, United States of America.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47906, United States of America.
authors.forename: Jian-Kang
authors.initials: JK
authors.lastname: Zhu
authors.affiliation: Laboratories of Structural Sciences/Structural Biology and Biochemistry, Van Andel Research Institute, N.E., Grand Rapids, Michigan, United States of America; State Key Laboratory of Drug Research, VARI-SIMM Center, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China.
authors.forename: H Eric
authors.initials: HE
authors.lastname: Xu
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
authors.forename: Kunchithapadam
authors.initials: K
authors.lastname: Swaminathan
authors.affiliation: Laboratories of Structural Sciences/Structural Biology and Biochemistry, Van Andel Research Institute, N.E., Grand Rapids, Michigan, United States of America.
authors.forename: Karsten
authors.initials: K
authors.lastname: Melcher
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000502:physiology; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D001692:Biological Transport / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000096:biosynthesis / Q000235:genetics*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism / Q000502:physiology; D011494:Protein Kinases / Q000378:metabolism*; D013312:Stress, Physiological / Q000235:genetics*; D014867:Water / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D014867:Water; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D011494:Protein Kinases; C472139:OST1 protein, Arabidopsis; C514757:HAB1 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases