title: Type One Protein Phosphatase 1 and Its Regulatory Protein Inhibitor 2 Negatively Regulate ABA Signaling.
abstract: The phytohormone abscisic acid (ABA) regulates plant growth, development and responses to biotic and abiotic stresses. The core ABA signaling pathway consists of three major components: ABA receptor (PYR1/PYLs), type 2C Protein Phosphatase (PP2C) and SNF1-related protein kinase 2 (SnRK2). Nevertheless, the complexity of ABA signaling remains to be explored. To uncover new components of ABA signal transduction pathways, we performed a yeast two-hybrid screen for SnRK2-interacting proteins. We found that Type One Protein Phosphatase 1 (TOPP1) and its regulatory protein, At Inhibitor-2 (AtI-2), physically interact with SnRK2s and also with PYLs. TOPP1 inhibited the kinase activity of SnRK2.6, and this inhibition could be enhanced by AtI-2. Transactivation assays showed that TOPP1 and AtI-2 negatively regulated the SnRK2.2/3/6-mediated activation of the ABA responsive reporter gene RD29B, supporting a negative role of TOPP1 and AtI-2 in ABA signaling. Consistent with these findings, topp1 and ati-2 mutant plants displayed hypersensitivities to ABA and salt treatments, and transcriptome analysis of TOPP1 and AtI-2 knockout plants revealed an increased expression of multiple ABA-responsive genes in the mutants. Taken together, our results uncover TOPP1 and AtI-2 as negative regulators of ABA signaling.
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Yueh-Ju
authors.initials: YJ
authors.lastname: Hou
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.|Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, China.
authors.forename: Yingfang
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.|Shanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, China.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.|Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.|Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, China.
authors.forename: Shaojun
authors.initials: S
authors.lastname: Xie
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Batelli
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Bangshing
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Cheng-Guo
authors.initials: CG
authors.lastname: Duan
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Xingang
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Lu
authors.initials: L
authors.lastname: Xing
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Mingguang
authors.initials: M
authors.lastname: Lei
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.|Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yan
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.|Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, United States of America.|Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, China.
authors.forename: Jian-Kang
authors.initials: JK
authors.lastname: Zhu
mesh_terms: D000040:Abscisic Acid / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D057773:Cold Shock Proteins and Peptides / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D054645:Protein Phosphatase 1 / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D057773:Cold Shock Proteins and Peptides; D026901:Membrane Transport Proteins; C540976:AT4G17870 protein, Arabidopsis; C000595439:RD29B protein, Arabidopsis; C492978:SnRK2 protein, Arabidopsis; D000040:Abscisic Acid; D011494:Protein Kinases; C472139:OST1 protein, Arabidopsis; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; C463465:AHG3 protein, Arabidopsis; C558185:AtI-2 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; C000609624:TOPP1 protein, Arabidopsis