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Bheri M, Mahiwal S, Sanyal SK, Pandey GK. Plant protein phosphatases: What do we know about their mechanism of action? FEBS J 2020; 288:756-785. [PMID: 32542989 DOI: 10.1111/febs.15454] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 05/27/2020] [Accepted: 06/09/2020] [Indexed: 12/30/2022]
Abstract
Protein phosphorylation is a major reversible post-translational modification. Protein phosphatases function as 'critical regulators' in signaling networks through dephosphorylation of proteins, which have been phosphorylated by protein kinases. A large understanding of their working has been sourced from animal systems rather than the plant or the prokaryotic systems. The eukaryotic protein phosphatases include phosphoprotein phosphatases (PPP), metallo-dependent protein phosphatases (PPM), protein tyrosine (Tyr) phosphatases (PTP), and aspartate (Asp)-dependent phosphatases. The PPP and PPM families are serine(Ser)/threonine(Thr)-specific phosphatases (STPs), while PTP family is Tyr specific. Dual-specificity phosphatases (DsPTPs/DSPs) dephosphorylate Ser, Thr, and Tyr residues. PTPs lack sequence homology with STPs, indicating a difference in catalytic mechanisms, while the PPP and PPM families share a similar structural fold indicating a common catalytic mechanism. The catalytic cysteine (Cys) residue in the conserved HCX5 R active site motif of the PTPs acts as a nucleophile during hydrolysis. The PPP members require metal ions, which coordinate the phosphate group of the substrate, followed by a nucleophilic attack by a water molecule and hydrolysis. The variable holoenzyme assembly of protein phosphatase(s) and the overlap with other post-translational modifications like acetylation and ubiquitination add to their complexity. Though their functional characterization is extensively reported in plants, the mechanistic nature of their action is still being explored by researchers. In this review, we exclusively overview the plant protein phosphatases with an emphasis on their mechanistic action as well as structural characteristics.
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Affiliation(s)
- Malathi Bheri
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
| | - Swati Mahiwal
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
| | - Sibaji K Sanyal
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
| | - Girdhar K Pandey
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
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Li Y, Wang Y, Tan S, Li Z, Yuan Z, Glanc M, Domjan D, Wang K, Xuan W, Guo Y, Gong Z, Friml J, Zhang J. Root Growth Adaptation is Mediated by PYLs ABA Receptor-PP2A Protein Phosphatase Complex. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:1901455. [PMID: 32042554 PMCID: PMC7001640 DOI: 10.1002/advs.201901455] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/23/2019] [Indexed: 05/20/2023]
Abstract
Plant root architecture dynamically adapts to various environmental conditions, such as salt-containing soil. The phytohormone abscisic acid (ABA) is involved among others also in these developmental adaptations, but the underlying molecular mechanism remains elusive. Here, a novel branch of the ABA signaling pathway in Arabidopsis involving PYR/PYL/RCAR (abbreviated as PYLs) receptor-protein phosphatase 2A (PP2A) complex that acts in parallel to the canonical PYLs-protein phosphatase 2C (PP2C) mechanism is identified. The PYLs-PP2A signaling modulates root gravitropism and lateral root formation through regulating phytohormone auxin transport. In optimal conditions, PYLs ABA receptor interacts with the catalytic subunits of PP2A, increasing their phosphatase activity and thus counteracting PINOID (PID) kinase-mediated phosphorylation of PIN-FORMED (PIN) auxin transporters. By contrast, in salt and osmotic stress conditions, ABA binds to PYLs, inhibiting the PP2A activity, which leads to increased PIN phosphorylation and consequently modulated directional auxin transport leading to adapted root architecture. This work reveals an adaptive mechanism that may flexibly adjust plant root growth to withstand saline and osmotic stresses. It occurs via the cross-talk between the stress hormone ABA and the versatile developmental regulator auxin.
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Affiliation(s)
- Yang Li
- State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological SciencesChina Agricultural UniversityBeijing100193China
| | - Yaping Wang
- State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological SciencesChina Agricultural UniversityBeijing100193China
| | - Shutang Tan
- Institute of Science and Technology AustriaAm Campus 13400KlosterneuburgAustria
| | - Zhen Li
- State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological SciencesChina Agricultural UniversityBeijing100193China
| | - Zhi Yuan
- State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological SciencesChina Agricultural UniversityBeijing100193China
| | - Matouš Glanc
- Institute of Science and Technology AustriaAm Campus 13400KlosterneuburgAustria
| | - David Domjan
- Institute of Science and Technology AustriaAm Campus 13400KlosterneuburgAustria
| | - Kai Wang
- State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological SciencesChina Agricultural UniversityBeijing100193China
| | - Wei Xuan
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower‐Middle Reaches of the Yangtze RiverNanjing Agricultural UniversityNanjing210095China
| | - Yan Guo
- State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological SciencesChina Agricultural UniversityBeijing100193China
| | - Zhizhong Gong
- State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological SciencesChina Agricultural UniversityBeijing100193China
| | - Jiří Friml
- Institute of Science and Technology AustriaAm Campus 13400KlosterneuburgAustria
| | - Jing Zhang
- State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological SciencesChina Agricultural UniversityBeijing100193China
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Sun L, Pehlivan N, Esmaeili N, Jiang W, Yang X, Jarrett P, Mishra N, Zhu X, Cai Y, Herath M, Shen G, Zhang H. Co-overexpression of AVP1 and PP2A-C5 in Arabidopsis makes plants tolerant to multiple abiotic stresses. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 274:271-283. [PMID: 30080613 DOI: 10.1016/j.plantsci.2018.05.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/30/2018] [Accepted: 05/25/2018] [Indexed: 05/20/2023]
Abstract
Abiotic stresses are major threats to agricultural production. Drought and salinity as two of the major abiotic stresses cause billions of losses in agricultural productivity worldwide each year. Thus, it is imperative to make crops more tolerant. Overexpression of AVP1 or PP2A-C5 was previously shown to increase drought and salt stress tolerance, respectively, in transgenic plants. In this study, the hypothesis that co-overexpression of AVP1 and PP2A-C5 would combine their respective benefits and further improve salt tolerance was tested. The two genes were inserted into the same T-DNA region of the binary vector and then introduced into the Arabidopsis genome through Agrobacterium-mediated transformation. Transgenic Arabidopsis plants expressing both AVP1 and PP2A-C5 at relatively high levels were identified and analyzed. These plants displayed enhanced tolerance to NaCl compared to either AVP1 or PP2A-C5 overexpressing plants. They also showed tolerance to other stresses such as KNO3 and LiCl at harmful concentrations, drought, and phosphorus deficiency at comparable levels with either AVP1 or PP2A-C5 overexpressing plants. This study demonstrates that introducing multiple genes in single T-DNA region is an effective approach to create transgenic plants with enhanced tolerance to multiple stresses.
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Affiliation(s)
- Li Sun
- Department of Biological Sciences, Texas Tech University, Texas 79409, USA
| | - Necla Pehlivan
- Department of Biology, Recep Tayyip Erdogan University, Rize 53100, Turkey
| | - Nardana Esmaeili
- Department of Biological Sciences, Texas Tech University, Texas 79409, USA
| | - Weijia Jiang
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, Sichuan 610064, China
| | - Xiaojie Yang
- Henan Academy of Agricultural Sciences, Zhengzhou, Henan 450002, China
| | - Philip Jarrett
- Department of Biological Sciences, Texas Tech University, Texas 79409, USA
| | - Neelam Mishra
- Department of Biological Sciences, Texas Tech University, Texas 79409, USA
| | - Xunlu Zhu
- Department of Biological Sciences, Texas Tech University, Texas 79409, USA
| | - Yifan Cai
- Department of Biological Sciences, Texas Tech University, Texas 79409, USA
| | - Maheshika Herath
- Department of Biological Sciences, Texas Tech University, Texas 79409, USA
| | - Guoxin Shen
- Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang Province, China.
| | - Hong Zhang
- Department of Biological Sciences, Texas Tech University, Texas 79409, USA.
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Charpentier M, Sun J, Wen J, Mysore KS, Oldroyd GED. Abscisic acid promotion of arbuscular mycorrhizal colonization requires a component of the PROTEIN PHOSPHATASE 2A complex. PLANT PHYSIOLOGY 2014; 166:2077-90. [PMID: 25293963 PMCID: PMC4256847 DOI: 10.1104/pp.114.246371] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 10/02/2014] [Indexed: 05/20/2023]
Abstract
Legumes can establish intracellular interactions with symbiotic microbes to enhance their fitness, including the interaction with arbuscular mycorrhizal (AM) fungi. AM fungi colonize root epidermal cells to gain access to the root cortex, and this requires the recognition by the host plant of fungus-made mycorrhizal factors. Genetic dissection has revealed the symbiosis signaling pathway that allows the recognition of AM fungi, but the downstream processes that are required to promote fungal infection are poorly understood. Abscisic acid (ABA) has been shown to promote arbuscule formation in tomato (Solanum lycopersicum). Here, we show that ABA modulates the establishment of the AM symbiosis in Medicago truncatula by promoting fungal colonization at low concentrations and impairing it at high concentrations. We show that the positive regulation of AM colonization via ABA requires a PROTEIN PHOSPHATASE 2A (PP2A) holoenzyme subunit, PP2AB'1. Mutations in PP2AB'1 cause reduced levels of AM colonization that cannot be rescued with permissive ABA application. The action of PP2AB'1 in response to ABA is unlinked to the generation of calcium oscillations, as the pp2aB'1 mutant displays a normal calcium response. This contrasts with the application of high concentrations of ABA that impairs mycorrhizal factor-induced calcium oscillations, suggesting different modes of action of ABA on the AM symbiosis. Our work reveals that ABA functions at multiple levels to regulate the AM symbiosis and that a PP2A phosphatase is required for the ABA promotion of AM colonization.
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Affiliation(s)
- Myriam Charpentier
- Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom (M.C., J.S., G.E.D.O.); andSamuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (J.W., K.S.M.)
| | - Jongho Sun
- Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom (M.C., J.S., G.E.D.O.); andSamuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (J.W., K.S.M.)
| | - Jiangqi Wen
- Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom (M.C., J.S., G.E.D.O.); andSamuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (J.W., K.S.M.)
| | - Kirankumar S Mysore
- Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom (M.C., J.S., G.E.D.O.); andSamuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (J.W., K.S.M.)
| | - Giles E D Oldroyd
- Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom (M.C., J.S., G.E.D.O.); andSamuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (J.W., K.S.M.)
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Ballesteros I, Domínguez T, Sauer M, Paredes P, Duprat A, Rojo E, Sanmartín M, Sánchez-Serrano JJ. Specialized functions of the PP2A subfamily II catalytic subunits PP2A-C3 and PP2A-C4 in the distribution of auxin fluxes and development in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:862-72. [PMID: 23167545 DOI: 10.1111/tpj.12078] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 11/12/2012] [Accepted: 11/16/2012] [Indexed: 05/09/2023]
Abstract
Protein phosphorylation is a key molecular switch used to transmit information in biological signalling networks. The output of these signalling circuits is governed by the counteracting activities of protein kinases and phosphatases that determine the direction of the switch. Whereas many kinases have been functionally characterized, it has been difficult to ascribe precise cellular roles to plant phosphatases, which are encoded by enlarged gene families that may provide a high degree of genetic redundancy. In this work we have analysed the role in planta of catalytic subunits of protein phosphatase 2A (PP2A), a family encoded by five genes in Arabidopsis. Our results indicate that the two members of subfamily II, PP2A-C3 and PP2A-C4, have redundant functions in controlling embryo patterning and root development, processes that depend on auxin fluxes. Moreover, polarity of the auxin efflux carrier PIN1 and auxin distribution, determined with the DR5(pro) :GFP proxy, are affected by mutations in PP2A-C3 and PP2A-C4. Previous characterization of mutants in putative PP2A regulatory subunits had established a link between this class of phosphatases and PIN dephosphorylation and subcellular distribution. Building on those findings, the results presented here suggest that PP2A-C3 and PP2A-C4 catalyse this reaction and contribute critically to the establishment of auxin gradients for proper plant development.
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Affiliation(s)
- Isabel Ballesteros
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología CSIC, Campus Universidad Autónoma de Madrid, Cta. Colmenar Viejo km. 15,500, 28049 Madrid, Spain
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Dudits D, Abrahám E, Miskolczi P, Ayaydin F, Bilgin M, Horváth GV. Cell-cycle control as a target for calcium, hormonal and developmental signals: the role of phosphorylation in the retinoblastoma-centred pathway. ANNALS OF BOTANY 2011; 107:1193-202. [PMID: 21441245 PMCID: PMC3091804 DOI: 10.1093/aob/mcr038] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 10/06/2010] [Accepted: 01/07/2011] [Indexed: 05/22/2023]
Abstract
BACKGROUND During the life cycle of plants, both embryogenic and post-embryogenic growth are essentially based on cell division and cell expansion that are under the control of inherited developmental programmes modified by hormonal and environmental stimuli. Considering either stimulation or inhibition of plant growth, the key role of plant hormones in the modification of cell division activities or in the initiation of differentiation is well supported by experimental data. At the same time there is only limited insight into the molecular events that provide linkage between the regulation of cell-cycle progression and hormonal and developmental control. Studies indicate that there are several alternative ways by which hormonal signalling networks can influence cell division parameters and establish functional links between regulatory pathways of cell-cycle progression and genes and protein complexes involved in organ development. SCOPE An overview is given here of key components in plant cell division control as acceptors of hormonal and developmental signals during organ formation and growth. Selected examples are presented to highlight the potential role of Ca(2+)-signalling, the complex actions of auxin and cytokinins, regulation by transcription factors and alteration of retinoblastoma-related proteins by phosphorylation. CONCLUSIONS Auxins and abscisic acid can directly influence expression of cyclin, cyclin-dependent kinase (CDK) genes and activities of CDK complexes. D-type cyclins are primary targets for cytokinins and over-expression of CyclinD3;1 can enhance auxin responses in roots. A set of auxin-activated genes (AXR1-ARGOS-ANT) controls cell number and organ size through modification of CyclinD3;1 gene expression. The SHORT ROOT (SHR) and SCARECROW (SCR) transcriptional factors determine root patterning by activation of the CYCD6;1 gene. Over-expression of the EBP1 gene (plant homologue of the ErbB-3 epidermal growth factor receptor-binding protein) increased biomass by auxin-dependent activation of both D- and B-type cyclins. The direct involvement of auxin-binding protein (ABP1) in the entry into the cell cycle and the regulation of leaf size and morphology is based on the transcriptional control of D-cyclins and retinoblastoma-related protein (RBR) interacting with inhibitory E2FC transcriptional factor. The central role of RBRs in cell-cycle progression is well documented by a variety of experimental approaches. Their function is phosphorylation-dependent and both RBR and phospho-RBR proteins are present in interphase and mitotic phase cells. Immunolocalization studies showed the presence of phospho-RBR protein in spots of interphase nuclei or granules in mitotic prophase cells. The Ca(2+)-dependent phosphorylation events can be accomplished by the calcium-dependent, calmodulin-independent or calmodulin-like domain protein kinases (CDPKs/CPKs) phosphorylating the CDK inhibitor protein (KRP). Dephosphorylation of the phospho-RBR protein by PP2A phosphatase is regulated by a Ca(2+)-binding subunit.
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Affiliation(s)
- Dénes Dudits
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary.
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Singh A, Giri J, Kapoor S, Tyagi AK, Pandey GK. Protein phosphatase complement in rice: genome-wide identification and transcriptional analysis under abiotic stress conditions and reproductive development. BMC Genomics 2010. [PMID: 20637108 DOI: 10.1186/1471–2164–11-435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Protein phosphatases are the key components of a number of signaling pathways where they modulate various cellular responses. In plants, protein phosphatases constitute a large gene family and are reportedly involved in the regulation of abiotic stress responses and plant development. Recently, the whole complement of protein phosphatases has been identified in Arabidopsis genome. While PP2C class of serine/threonine phosphatases has been explored in rice, the whole complement of this gene family is yet to be reported. RESULTS In silico investigation revealed the presence of 132-protein phosphatase-coding genes in rice genome. Domain analysis and phylogenetic studies of evolutionary relationship categorized these genes into PP2A, PP2C, PTP, DSP and LMWP classes. PP2C class represents a major proportion of this gene family with 90 members. Chromosomal localization revealed their distribution on all the 12 chromosomes, with 42 genes being present on segmentally duplicated regions and 10 genes on tandemly duplicated regions of chromosomes. The expression profiles of 128 genes under salinity, cold and drought stress conditions, 11 reproductive developmental (panicle and seed) stages along with three stages of vegetative development were analyzed using microarray expression data. 46 genes were found to be differentially expressing in 3 abiotic stresses out of which 31 were up-regulated and 15 exhibited down-regulation. A total of 82 genes were found to be differentially expressing in different developmental stages. An overlapping expression pattern was found for abiotic stresses and reproductive development, wherein 8 genes were up-regulated and 7 down-regulated. Expression pattern of the 13 selected genes was validated employing real time PCR, and it was found to be in accordance with the microarray expression data for most of the genes. CONCLUSIONS Exploration of protein phosphatase gene family in rice has resulted in the identification of 132 members, which can be further divided into different classes phylogenetically. Expression profiling and analysis indicate the involvement of this large gene family in a number of signaling pathways triggered by abiotic stresses and their possible role in plant development. Our study will provide the platform from where; the expression pattern information can be transformed into molecular, cellular and biochemical characterization of members belonging to this gene family.
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Affiliation(s)
- Amarjeet Singh
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021, India
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Singh A, Giri J, Kapoor S, Tyagi AK, Pandey GK. Protein phosphatase complement in rice: genome-wide identification and transcriptional analysis under abiotic stress conditions and reproductive development. BMC Genomics 2010; 11:435. [PMID: 20637108 PMCID: PMC3091634 DOI: 10.1186/1471-2164-11-435] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 07/16/2010] [Indexed: 11/12/2022] Open
Abstract
Background Protein phosphatases are the key components of a number of signaling pathways where they modulate various cellular responses. In plants, protein phosphatases constitute a large gene family and are reportedly involved in the regulation of abiotic stress responses and plant development. Recently, the whole complement of protein phosphatases has been identified in Arabidopsis genome. While PP2C class of serine/threonine phosphatases has been explored in rice, the whole complement of this gene family is yet to be reported. Results In silico investigation revealed the presence of 132-protein phosphatase-coding genes in rice genome. Domain analysis and phylogenetic studies of evolutionary relationship categorized these genes into PP2A, PP2C, PTP, DSP and LMWP classes. PP2C class represents a major proportion of this gene family with 90 members. Chromosomal localization revealed their distribution on all the 12 chromosomes, with 42 genes being present on segmentally duplicated regions and 10 genes on tandemly duplicated regions of chromosomes. The expression profiles of 128 genes under salinity, cold and drought stress conditions, 11 reproductive developmental (panicle and seed) stages along with three stages of vegetative development were analyzed using microarray expression data. 46 genes were found to be differentially expressing in 3 abiotic stresses out of which 31 were up-regulated and 15 exhibited down-regulation. A total of 82 genes were found to be differentially expressing in different developmental stages. An overlapping expression pattern was found for abiotic stresses and reproductive development, wherein 8 genes were up-regulated and 7 down-regulated. Expression pattern of the 13 selected genes was validated employing real time PCR, and it was found to be in accordance with the microarray expression data for most of the genes. Conclusions Exploration of protein phosphatase gene family in rice has resulted in the identification of 132 members, which can be further divided into different classes phylogenetically. Expression profiling and analysis indicate the involvement of this large gene family in a number of signaling pathways triggered by abiotic stresses and their possible role in plant development. Our study will provide the platform from where; the expression pattern information can be transformed into molecular, cellular and biochemical characterization of members belonging to this gene family.
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Affiliation(s)
- Amarjeet Singh
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021, India
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Pernas M, García-Casado G, Rojo E, Solano R, Sánchez-Serrano JJ. A protein phosphatase 2A catalytic subunit is a negative regulator of abscisic acid signalling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 51:763-78. [PMID: 17617176 DOI: 10.1111/j.1365-313x.2007.03179.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The key regulatory role of abscisic acid (ABA) in many physiological processes in plants is well established. However, compared with other plant hormones, the molecular mechanisms underlying ABA signalling are poorly characterized. In this work, a specific catalytic subunit of protein phosphatase 2A (PP2Ac-2) has been identified as a component of the signalling pathway that represses responses to ABA. A loss-of-function pp2ac-2 mutant is hypersensitive to ABA. Moreover, pp2ac-2 plants have altered responses in developmental and environmental processes that are mediated by ABA, such as primary and lateral root development, seed germination and responses to drought and high salt and sugar stresses. Conversely, transgenic plants overexpressing PP2Ac-2 are less sensitive to ABA than wild type, a phenotype that is manifested in all the above-mentioned physiological processes. DNA microarray hybridization experiments reveal that PP2Ac-2 is negatively involved in ABA responses through regulation of ABA-dependent gene expression. Moreover, the results obtained indicate that ABA antagonistically regulates PP2Ac-2 expression and PP2Ac-2 activity thus allowing plant sensitivity to the hormone to be reset after induction. Phenotypic, genetic and gene expression data strongly suggest that PP2Ac-2 is a negative regulator of the ABA pathway. Activity of protein phosphatase 2A thus emerges as a key element in the control of ABA signalling.
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Affiliation(s)
- Mónica Pernas
- Centro Nacional de Biotecnología CSIC, Campus de Cantoblanco UAM, 28049, Madrid, Spain
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Xu C, Jing R, Mao X, Jia X, Chang X. A wheat (Triticum aestivum) protein phosphatase 2A catalytic subunit gene provides enhanced drought tolerance in tobacco. ANNALS OF BOTANY 2007; 99:439-50. [PMID: 17272305 PMCID: PMC2802960 DOI: 10.1093/aob/mcl285] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Accepted: 11/21/2006] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND AIMS Multiple copies of genes encoding the catalytic subunit (c) of protein phosphatase 2A (PP2A) are commonly found in plants. For some of these genes, expression is up-regulated under water stress. The aim of this study was to investigate expression and characterization of TaPP2Ac-1 from Triticum aestivum, and to evaluate the effects of TaPP2Ac-1 on Nicotiana benthamiana in response to water stress. METHODS TaPP2Ac-1 cDNA was isolated from wheat by in silico identification and RT-PCR amplification. Transcript levels of TaPP2Ac-1 were examined in wheat responding to water deficit. Copy numbers of TaPP2Ac-1 in wheat genomes and subcellular localization in onion epidermal cells were studied. Enzyme properties of the recombinant TaPP2Ac-1 protein were determined. In addition, studies were carried out in tobacco plants with pCAPE2-TaPP2Ac-1 under water-deficit conditions. KEY RESULTS TaPP2Ac-1 cDNA was cloned from wheat. Transcript levels of TaPP2Ac-1 in wheat seedlings were up-regulated under drought condition. One copy for this TaPP2Ac-1 was present in each of the three wheat genomes. TaPP2Ac-1 fused with GFP was located in the nucleus and cytoplasm of onion epidermis cells. The recombinant TaPP2Ac-1 gene was over-expressed in Escherichia coli and encoded a functional serine/threonine phosphatase. Transgenic tobacco plants over-expressing TaPP2Ac-1 exhibited stronger drought tolerance than non-transgenic tobacco plants. CONCLUSIONS Tobacco plants with pCAPE2-TaPP2Ac-1 appeared to be resistant to water deficit, as shown by their higher capacity to maintain leaf relative water content, leaf cell-membrane stability index, water-retention ability and water use efficiency under water stress. The results suggest that the physiological role of TaPP2Ac-1 is related to drought stress response, possibly through its involvement in drought-responding signal transduction pathways.
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Affiliation(s)
| | - Ruilian Jing
- The National Key Facility for Crop Gene Resources and Genetic Improvement, Key Laboratory of Crop Germplasm & Biotechnology, Ministry of Agriculture, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
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Yu RMK, Wong MML, Jack RW, Kong RYC. Structure, evolution and expression of a second subfamily of protein phosphatase 2A catalytic subunit genes in the rice plant (Oryza sativa L.). PLANTA 2005; 222:757-68. [PMID: 16021503 DOI: 10.1007/s00425-005-0018-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2005] [Accepted: 04/28/2005] [Indexed: 05/03/2023]
Abstract
Protein phosphatase 2A (PP2A) is one of the major serine/threonine protein phosphatases in the cell and plays a variety of regulatory roles in metabolism and signal transduction. Previously, we described the structure and expression of two genes encoding PP2A catalytic subunits (PP2Ac)--OsPP2A-1 and OsPP2A-3--in the rice plant (Yu et al. 2003). Here, we report the isolation and characterisation of a second structurally distinguishable PP2Ac subfamily comprised of three additional isogenes, OsPP2A-2, OsPP2A-4 (each containing ten introns) and OsPP2A-5 (which contains nine introns). Northern blot analysis demonstrated that the three isogenes are ubiquitously expressed in all rice tissues during plant development, and differentially expressed in response to high salinity and the combined stresses of drought and heat. Phylogenetic analyses indicated that the two PP2Ac subfamilies are descended from two ancient lineages, which derived from gene duplications that occurred after the monocotyledon-dicotyledon split. In the second subfamily, it is proposed that two duplication events were involved; in which, the initial duplication of a ten-intron primordial gene yielded OsPP2A-2 and the progenitor of OsPP2A-4 and OsPP2A-5. The OsPP2A-4/OsPP2A-5 progenitor, in turn, underwent a second duplication event, resulting in the present day OsPP2A-4 and OsPP2A-5. It is proposed that loss of the 5'-most intron from OsPP2A-5 occurred after these two duplication events.
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Affiliation(s)
- Richard Man Kit Yu
- Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
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Abstract
Phosphorylation and dephosphorylation of a protein often serve as an "on-and-off" switch in the regulation of cellular activities. Recent studies demonstrate the involvement of protein phosphorylation in almost all signaling pathways in plants. A significant portion of the sequenced Arabidopsis genome encodes protein kinases and protein phosphatases that catalyze reversible phosphorylation. For optimal regulation, kinases and phosphatases must strike a balance in any given cell. Only a very small fraction of the thousands of protein kinases and phosphatases in plants has been studied experimentally. Nevertheless, the available results have demonstrated critical functions for these enzymes in plant growth and development. While serine/threonine phosphorylation is widely accepted as a predominant modification of plant proteins, the function of tyrosine phosphorylation, desptie its overwhelming importance in animal systems, had been largely neglected until recently when tyrosine phosphatases (PTPs) were characterized from plants. This review focuses on the structure, regulation, and function of protein phosphatases in higher plants.
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Affiliation(s)
- Sheng Luan
- Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, California 94720, USA.
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13
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Terol J, Bargues M, Carrasco P, Pérez-Alonso M, Paricio N. Molecular characterization and evolution of the protein phosphatase 2A B' regulatory subunit family in plants. PLANT PHYSIOLOGY 2002; 129:808-22. [PMID: 12068121 PMCID: PMC161703 DOI: 10.1104/pp.020004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Type 2A serine/threonine protein phosphatases (PP2A) are important components in the reversible protein phosphorylation events in plants and other organisms. PP2A proteins are oligomeric complexes constituted by a catalytic subunit and several regulatory subunits that modulate the activity of these phosphatases. The analysis of the complete genome of Arabidopsis allowed us to characterize four novel genes, AtB'epsilon, AtB'zeta, AtB'eta, and AtB'theta;, belonging to the PP2A B' regulatory subunit family. Because four genes of this type had been described previously, this family is composed of eight members. Reverse transcriptase-polymerase chain reaction experiments showed that AtB'epsilon mRNAs are present in all Arabidopsis tissues analyzed, and their levels do not respond significantly to heat stress. Expressed sequence tags corresponding to AtB'zeta, AtB'eta, and AtB'theta; have been identified, indicating that the new genes are actively transcribed. The genomic organization of this family of PP2A regulatory subunits is reported, as well as its chromosomal location. An extensive survey of the family has been carried out in plants, characterizing B' subunits in a number of different species, and performing a phylogenetic study that included several B' regulatory proteins from animals. Our results indicate that the animal and plant proteins have evolved independently, that there is a relationship between the number of B' isoforms and the complexity of the organism, and that there are at least three main subfamilies of regulatory subunits in plants, which we have named alpha, eta, and kappa.
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Affiliation(s)
- Javier Terol
- Departament de Genetica, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Spain
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14
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Awotunde OS, Sugajska E, Zolnierowicz S, Muszyńska G. Characterisation of two protein phosphatase 2A holoenzymes from maize seedlings. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1480:65-76. [PMID: 11004556 DOI: 10.1016/s0167-4838(00)00097-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Two holoenzymes of protein phosphatase 2A (PP2A), designated PP2AI and PP2AII, were purified from maize seedlings. The subunit composition of maize holoenzymes generally resembled those of animal PP2A. Using SDS/PAGE and Western blots with antibodies generated against peptides derived from animal PP2A, we established the subunit composition of plant protein phosphatase 2A. In both maize holoenzymes, a 38000 catalytic (PP2Ac) and a 66000 constant regulatory subunit (A) constituting the core dimer of PP2A were present. In addition, PP2AI (180000-200000) contained a protein of 57000 which reacted with antibodies generated against the peptide (EFDYLKSLEIEE) conserved in all eukaryotic Balpha regulatory subunits. In contrast, none of the proteins visualised in PP2AII (140000-160000) by double staining reacted with these antibodies. The activity of PP2AI measured with (32)P-labelled phosphorylase a in the presence of protamine and ammonium sulfate is about two times higher than that of PP2AII. PP2AI and PP2AII displayed different patterns of activation by protamine, polylysine and histone H1 and exhibit high sensitivity toward inhibition by okadaic acid. The data obtained provide direct biochemical evidence for the existence in plants of PP2A holoenzymes composed of a catalytic subunit complexed with one or two regulatory subunits.
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Affiliation(s)
- O S Awotunde
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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15
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Deruère J, Jackson K, Garbers C, Söll D, Delong A. The RCN1-encoded A subunit of protein phosphatase 2A increases phosphatase activity in vivo. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1999; 20:389-399. [PMID: 10607292 DOI: 10.1046/j.1365-313x.1999.00607.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Protein phosphatase 2A (PP2A), a heterotrimeric serine/threonine-specific protein phosphatase, comprises a catalytic C subunit and two distinct regulatory subunits, A and B. The RCN1 gene encodes one of three A regulatory subunits in Arabidopsis thaliana. A T-DNA insertion mutation at this locus impairs root curling, seedling organ elongation and apical hypocotyl hook formation. We have used in vivo and in vitro assays to gauge the impact of the rcn1 mutation on PP2A activity in seedlings. PP2A activity is decreased in extracts from rcn1 mutant seedlings, and this decrease is not due to a reduction in catalytic subunit expression. Roots of mutant seedlings exhibit increased sensitivity to the phosphatase inhibitors okadaic acid and cantharidin in organ elongation assays. Shoots of dark-grown, but not light-grown seedlings also show increased inhibitor sensitivity. Furthermore, cantharidin treatment of wild-type seedlings mimics the rcn1 defect in root curling, root waving and hypocotyl hook formation assays. In roots of wild-type seedlings, RCN1 mRNA is expressed at high levels in root tips, and accumulates to lower levels in the pericycle and lateral root primordia. In shoots, RCN1 is expressed in the apical hook and the basal, rapidly elongating cells in etiolated hypocotyls, and in the shoot meristem and leaf primordia of light-grown seedlings. Our results show that the wild-type RCN1-encoded A subunit functions as a positive regulator of the PP2A holoenzyme, increasing activity towards substrates involved in organ elongation and differential cell elongation responses such as root curling.
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Affiliation(s)
- J Deruère
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
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16
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Haynes JG, Hartung AJ, Hendershot JD, Passingham RS, Rundle SJ. Molecular characterization of the B' regulatory subunit gene family of Arabidopsis protein phosphatase 2A. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 260:127-36. [PMID: 10091592 DOI: 10.1046/j.1432-1327.1999.00154.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Type 2A serine/threonine protein phosphatases (PP2A) have been implicated as important mediators of a diverse array of reversible protein phosphorylation events in plants. We have identified a novel Arabidopsis gene (AtB' delta) which encodes a 55-kDa B' type regulatory subunit of PP2A. The protein encoded by this gene is 57-63% identical and 69-74% similar to the previously identified AtB' genes. The AtB' delta gene appears to be expressed in all Arabidopsis organs indicating its protein product has a basic housekeeping function in plant cells. Unlike certain mRNAs derived from the AtB' gamma gene, AtB' delta mRNAs do not fluctuate significantly in response to heat stress. Further analysis of cDNA sequences derived from the AtB' genes identified an alternatively spliced cDNA derived from AtB' gamma. This cDNA differs from the previously identified AtB' gamma cDNA by the absence of a 133-bp region in its 5' untranslated region. The missing 133-bp region appears to constitute an unspliced intron and its presence in the AtB' gamma gene was confirmed by PCR using Arabidopsis genomic DNA as a template. AtB' gamma mRNA containing the 133-bp intron accumulate in all Arabidopsis organs and their levels fluctuate differentially in response to heat stress. The 133-bp insert contains two short open reading frames and hence might serve as a translational control mechanism affecting AtB' gamma protein synthesis. Finally we show, using both the yeast two hybrid system and in vitro binding assays, that the B' subunit of Arabidopsis PP2A is able to associate with other PP2A subunits, supporting the notion that the B' protein serves as a regulator of PP2A activity in plants.
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Affiliation(s)
- J G Haynes
- Department of Biology, Western Carolina University, Cullowhee, NC 28723, USA
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17
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Pérez-Callejón E, Casamayor A, Pujol G, Camps M, Ferrer A, Ariño J. Molecular cloning and characterization of two phosphatase 2A catalytic subunit genes from Arabidopsis thaliana. Gene 1998; 209:105-12. [PMID: 9524239 DOI: 10.1016/s0378-1119(98)00013-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The plant Arabidopsis thaliana contains five isoforms of the catalytic subunit of protein phosphatase 2A (PP2A) that can be grouped into two families, one composed by isoforms PP2A-1, -2 and -5 and the other composed by isoforms PP2A-3 and PP2A-4. An Arabidopsis genomic library was screened and several clones corresponding to genes PP2A-3 and PP2A-4 were isolated and analysed. Both genes span over approximately 4.5kbp and are composed of 11 exons and 10 introns that show identical organization. Their untranslated regions are also highly conserved, suggesting that the two genes derive from a common ancestral gene. However, the position of intron/exon junctions completely differs from that of the human PP2A genes. Two transcription start sites have been found in the PP2A-3 gene, the major one mapping at nucleotide position -188 from the translation start codon, whereas only one is observed in PP2A-4 (-145). Functional gene promoter analysis reveals that elements required for transient expression of PP2A-3 and PP2A-4 on a protoplast system are contained within a region of about 600bp upstream from the transcription start sites. This is the first report on the cloning and characterization of genes encoding catalytic subunits of Ser/Thr protein phosphatases 2A in higher plants.
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Affiliation(s)
- E Pérez-Callejón
- Unitat de Bioquímica, Facultat de Farmacia, Universitat de Barcelona, Pça. Pius XII s/n, Barcelona 08028, Spain
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18
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Lessard P, Kreis M, Thomas M. [Protein phosphatases and protein kinases in higher plants]. COMPTES RENDUS DE L'ACADEMIE DES SCIENCES. SERIE III, SCIENCES DE LA VIE 1997; 320:675-88. [PMID: 9377173 DOI: 10.1016/s0764-4469(97)84815-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The recent gain in knowledge concerning enzymes involved in signal transduction pathways is a direct consequence of the considerable advances made in molecular biology. Protein kinases and protein phosphatases, the two major enzymes implicated in post-translational modifications, have been studied in particular. The number of characterized plant genes and/or cDNAs encoding these enzymes is increasing everyday. Since 1991, 26 genes and cDNAs coding for plant protein phosphatases have been isolated and characterized. The huge number of protein kinases (estimated at several thousands) makes it impossible to give an exhaustive list of the genes already identified, but a classification of these enzymes, based on phylogenetic criteria, allows us to appreciate the range of functions this protein family may play in plants.
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Affiliation(s)
- P Lessard
- Laboratoire de biologie du développement des plantes, université de Paris-Sud, Orsay, France.
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19
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Latorre KA, Harris DM, Rundle SJ. Differential expression of three Arabidopsis genes encoding the B' regulatory subunit of protein phosphatase 2A. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 245:156-63. [PMID: 9128737 DOI: 10.1111/j.1432-1033.1997.00156.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Numerous plant processes ranging from signal transduction to metabolism appear to be mediated, in part, by type 2A protein serine/threonine phosphatases (PP2A). In an effort to identify factors that control the activity of this enzyme in plants, we have isolated and characterized DNA sequences encoding the B' regulatory subunit of PP2A from Arabidopsis thaliana. Specifically, we used PCR to amplify a segment of Arabidopsis cDNA that encodes a conserved section of the B' polypeptide. This PCR fragment was subsequently used as a probe to screen an Arabidopsis cDNA library and cDNA clones derived from three distinct genes were identified. The AtB' alpha and AtB' beta genes encode highly similar 57-kDa B' regulatory subunits while the third gene, AtB' gamma, encodes a more divergent 59-kDa B' protein. A comparison of the three Arabidopsis B' polypeptides to those of yeast and animals shows the core region of this protein to be the most conserved while the amino and carboxy termini vary both in length and sequence. Genomic Southern blots indicate that at most the Arabidopsis genome contains five genes encoding the B' regulatory subunit. The three genes identified in this study are expressed in all Arabidopsis organs, albeit at varying levels. In addition, mRNAs derived from the three genes accumulate differentially in response to heat shock. Our results indicate that the activity of plant PP2A might be regulated by a B' type regulatory subunit similar to those found in animals and yeast, and suggest possible roles for B'-containing PP2A complexes within plant cells.
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Affiliation(s)
- K A Latorre
- Department of Biology, Western Carolina University, Cullowhee NC, USA
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20
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Abstract
Posttranslational modification of proteins by phosphorylation is a universal mechanism for regulating diverse biological functions. Recognition that many cellular proteins are reversibly phosphorylated in response to external stimuli or intracellular signals has generated an ongoing interest in identifying and characterizing plant protein kinases and protein phosphatases that modulate the phosphorylation status of proteins. This review discusses recent advances in our understanding of the structure, regulation, and function of plant protein phosphatases. Three major classes of enzymes have been reported in plants that are homologues of the mammalian type-1, -2A, and -2C protein serine/threonine phosphatases. Molecular genetic and biochemical studies reveal a role for some of these enzymes in signal transduction, cell cycle progression, and hormonal regulation. Studies also point to the presence of additional phosphatases in plants that are unrelated to these major classes.
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Affiliation(s)
- Robert D. Smith
- AgBiotech Center, Rutgers University, New Brunswick, New Jersey 08903-0231, Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
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21
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Corum JW, Hartung AJ, Stamey RT, Rundle SJ. Characterization of DNA sequences encoding a novel isoform of the 55 kDa B regulatory subunit of the type 2A protein serine/threonine phosphatase of Arabidopsis thaliana. PLANT MOLECULAR BIOLOGY 1996; 31:419-427. [PMID: 8756607 DOI: 10.1007/bf00021804] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We have identified a novel gene (AtB beta) encoding a previously uncharacterized isoform of the B regulatory subunit of the type 2A serine/threonine protein phosphatase (PP2A) of Arabidopsis, and show that mRNA derived from the AtB beta gene accumulates in all Arabidopsis organs. In addition, we examined the expression of the three genes encoding the A regulatory subunit of Arabidopsis PP2A and show these genes are expressed in all organs as well. Taken together, our results suggest a myriad of PP2A subunit combinations, possibly with distinct substrate specificities, may occur within each Arabidopsis cell.
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Affiliation(s)
- J W Corum
- Department of Biology, Western Carolina University, Cullowhee, NC 28723, USA
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