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Obroucheva NV. Cell elongation as an inseparable component of growth in terrestrial plants. Russ J Dev Biol 2011. [DOI: 10.1134/s1062360408010049] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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52
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Functional Classification of Plant Plasma Membrane Transporters. THE PLANT PLASMA MEMBRANE 2011. [DOI: 10.1007/978-3-642-13431-9_6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Plant Aquaporins: Roles in Water Homeostasis, Nutrition, and Signaling Processes. SIGNALING AND COMMUNICATION IN PLANTS 2011. [DOI: 10.1007/978-3-642-14369-4_1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Sampedro J, Pardo B, Gianzo C, Guitián E, Revilla G, Zarra I. Lack of α-xylosidase activity in Arabidopsis alters xyloglucan composition and results in growth defects. PLANT PHYSIOLOGY 2010; 154:1105-15. [PMID: 20801759 PMCID: PMC2971592 DOI: 10.1104/pp.110.163212] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 08/23/2010] [Indexed: 05/19/2023]
Abstract
Xyloglucan is the main hemicellulose in the primary cell walls of most seed plants and is thought to play a role in regulating the separation of cellulose microfibrils during growth. Xylose side chains block the degradation of the backbone, and α-xylosidase activity is necessary to remove them. Two Arabidopsis (Arabidopsis thaliana) mutant lines with insertions in the α-xylosidase gene AtXYL1 were characterized in this work. Both lines showed a reduction to undetectable levels of α-xylosidase activity against xyloglucan oligosaccharides. This reduction resulted in the accumulation of XXXG and XXLG in the liquid growth medium of Atxyl1 seedlings. The presence of XXLG suggests that it is a poor substrate for xyloglucan β-galactosidase. In addition, the polymeric xyloglucan of Atxyl1 lines was found to be enriched in XXLG subunits, with a concomitant decrease in XXFG and XLFG. This change can be explained by extensive exoglycosidase activity at the nonreducing ends of xyloglucan chains. These enzymes could thus have a larger role than previously thought in the metabolism of xyloglucan. Finally, Atxyl1 lines showed a reduced ability to control the anisotropic growth pattern of different organs, pointing to the importance of xyloglucan in this process. The promoter of AtXYL1 was shown to direct expression to many different organs and cell types undergoing cell wall modifications, including trichomes, vasculature, stomata, and elongating anther filaments.
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Tran HT, Qian W, Hurley BA, She YM, Wang D, Plaxton WC. Biochemical and molecular characterization of AtPAP12 and AtPAP26: the predominant purple acid phosphatase isozymes secreted by phosphate-starved Arabidopsis thaliana. PLANT, CELL & ENVIRONMENT 2010; 33:1789-803. [PMID: 20545876 DOI: 10.1111/j.1365-3040.2010.02184.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Plant purple acid phosphatases (PAPs) belong to a large multigene family whose specific functions in Pi metabolism are poorly understood. Two PAP isozymes secreted by Pi-deficient (-Pi) Arabidopsis thaliana were purified from culture filtrates of -Pi suspension cells. They correspond to an AtPAP12 (At2g27190) homodimer and AtPAP26 (At5g34850) monomer composed of glycosylated 60 and 55 kDa subunit(s), respectively. Each PAP exhibited broad pH activity profiles centred at pH 5.6, and overlapping substrate specificities. Concanavalin-A chromatography resolved a pair of secreted AtPAP26 glycoforms. AtPAP26 is dual targeted during Pi stress because it is also the principal intracellular (vacuolar) PAP up-regulated by -Pi Arabidopsis. Differential glycosylation appears to influence the subcellular targeting and substrate selectivity of AtPAP26. The significant increase in secreted acid phosphatase activity of -Pi seedlings was correlated with the appearance of immunoreactive AtPAP12 and AtPAP26 polypeptides. Analysis of atpap12 and atpap26 T-DNA mutants verified that AtPAP12 and AtPAP26 account for most of the secreted acid phosphatase activity of -Pi wild-type seedlings. Semi-quantitative RT-PCR confirmed that transcriptional controls exert little influence on the up-regulation of AtPAP26 during Pi stress, whereas AtPAP12 transcripts correlate well with relative levels of secreted AtPAP12 polypeptides. We hypothesize that AtPAP12 and AtPAP26 facilitate Pi scavenging from soil-localized organophosphates during nutritional Pi deprivation.
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Affiliation(s)
- Hue T Tran
- Department of Biology, Queen's University, Kingston, Ontario K7L3N6, Canada
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Schnell JA, Han S, Miki BL, Johnson DA. Soybean peroxidase propeptides are functional signal peptides and increase the yield of a foreign protein. PLANT CELL REPORTS 2010; 29:987-96. [PMID: 20535473 DOI: 10.1007/s00299-010-0884-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/12/2010] [Accepted: 05/26/2010] [Indexed: 05/29/2023]
Abstract
Elements that contribute to the high, stable yield of soybean peroxidase (SBP) in soybean seed coats can be exploited in the development of this tissue as a protein production platform. SBP contains an N-terminal and a C-terminal propeptide that are predicted to direct vacuolar targeting; this may be one factor that contributes to its high yield and stability. We characterized the function of the SBP propeptides and investigated their ability to increase the yield of a foreign protein in a heterologous plant system. SBP propeptides are functional signal peptides capable of directing vacuolar transport in Arabidopsis. The use of these propeptides as well as an endoplasmic reticulum (ER)-retention signal to direct a foreign protein to the apoplast, ER, or vacuole can significantly increase yield and will therefore be useful for the development of the seed coat as a protein production platform. We also demonstrate that growth conditions may have a significant impact on the yield of a foreign protein and that this may be subcellular compartment-specific.
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Affiliation(s)
- Jaimie A Schnell
- Ottawa-Carleton Institute of Biology, University of Ottawa, PO Box 450, Station A, Ottawa, ON, K1N 6N5, Canada
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Pradedova EV, Tolpygina OA, Isheeva OD, Putilina TE, Salyaev RK. Glutathione and glutathione-S-transferase activities of the vacuoles of the beet (Beta vulgaris L.) roots. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2010; 433:275-8. [PMID: 20711876 DOI: 10.1134/s0012496610040113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Indexed: 11/22/2022]
Affiliation(s)
- E V Pradedova
- Institute of Plant Physiology and Biochemistry, Russian Academy of Sciences, ul. Lermontova 132, Irkutsk, Russia
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Vacuolar ion channels: Roles in plant nutrition and signalling. FEBS Lett 2010; 584:1982-8. [DOI: 10.1016/j.febslet.2010.02.050] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 02/17/2010] [Accepted: 02/18/2010] [Indexed: 11/19/2022]
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Saito A, Saito M, Ichikawa Y, Yoshiba M, Tadano T, Miwa E, Higuchi K. Difference in the distribution and speciation of cellular nickel between nickel-tolerant and non-tolerant Nicotiana tabacum L. cv. BY-2 cells. PLANT, CELL & ENVIRONMENT 2010; 33:174-87. [PMID: 19906154 DOI: 10.1111/j.1365-3040.2009.02068.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
To evaluate Ni dynamics at the subcellular level, the distribution and speciation of Ni were determined in wild-type (WT) and Ni-tolerant (NIT) tobacco BY-2 cell lines. When exposed to low but toxic levels of Ni, NIT cells were found to contain 2.5-fold more Ni (14% of whole-cell Ni values) in their cell walls than WT cells (6% of whole-cell Ni values). In addition to higher levels of Ni in the apoplast, a higher proportion (94%) of symplastic Ni was localized in the vacuoles of NIT cells than in the vacuoles of WT cells (81%). The concentration of cytosolic Ni in the NIT cells was significantly lower (18 nmol g(-1) FW) than that in the WT cells (85 nmol g(-1) FW). In silico simulation showed that 95% of vacuolar Ni was in the form of Ni-citrate complexes, and that free Ni(2+) was virtually absent in the NIT cells. On the other hand, the amount of free metal ions was markedly increased in WT cells because free citrate was depleted by chelation of Ni. A protoplast viability assay using BCECF-AM further demonstrated that the main mechanism that confers strong Ni tolerance was present in the symplast as opposed to the cell wall.
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Affiliation(s)
- Akihiro Saito
- Laboratory of Plant Production Chemistry, Department of Applied Biology and Chemistry, Tokyo University of Agriculture, Tokyo 156-8502, Japan
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Fontes N, Silva R, Vignault C, Lecourieux F, Gerós H, Delrot S. Purification and functional characterization of protoplasts and intact vacuoles from grape cells. BMC Res Notes 2010; 3:19. [PMID: 20181000 PMCID: PMC2830944 DOI: 10.1186/1756-0500-3-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2009] [Accepted: 01/22/2010] [Indexed: 11/18/2022] Open
Abstract
Background During grape berry ripening, the vacuoles accumulate water, sugars and secondary metabolites, causing great impact in plant productivity and wine quality. However, the molecular basis of these compartmentation processes is still poorly understood. As in many species, the major bottleneck to study these aspects in grapevine is to obtain highly purified vacuoles with a good yield. The present paper describes an isolation method of protoplasts and intact vacuoles from grape berry cells and their functional characterization by transport and cytometric assays. Findings Protoplasts were prepared by enzymatic digestion of grape cells, and vacuoles were released and purified by a Ficoll step gradient centrifugation. The tonoplast stained strongly with the fluorescent dye FM1-43 and most vacuoles maintained an internal acidic pH, as assessed by Neutral Red. Flow cytometry analysis of vacuole samples incubated with the calcium-sensitive fluorescent probe Fluo-4 AM revealed a well-defined sub-population of intact vacuoles. As assessed by the pH-sensitive probe ACMA, intact vacuoles generated and maintained a pH gradient through the activity of V-ATPase and V-PPase and were able to transport Ca2+ via a proton-dependent transport system. Conclusions Highly pure, intact and functional protoplast and vacuole populations from grape cells were obtained with the present method, which revealed to be fast and efficient. The capacity of the vacuole population to sequester protons and accumulate Ca2+ strongly suggests the intactness and physiological integrity of these extremely fragile organelles. Grapevine protoplasts and vacuoles may be used as models for both basic research and biotechnological approaches, such as proteomics, solute uptake and compartmentation, toxicological assessments and breeding programs.
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Affiliation(s)
- Natacha Fontes
- Centro de Investigação e de Tecnologias Agro-Ambientais e Biológicas (CITAB), Portugal.
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63
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Huizinga DH, Denton R, Koehler KG, Tomasello A, Wood L, Sen SE, Crowell DN. Farnesylcysteine lyase is involved in negative regulation of abscisic acid signaling in Arabidopsis. MOLECULAR PLANT 2010; 3:143-55. [PMID: 19969520 PMCID: PMC2807925 DOI: 10.1093/mp/ssp091] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 09/22/2009] [Indexed: 05/21/2023]
Abstract
The Arabidopsis FCLY gene encodes a specific farnesylcysteine (FC) lyase, which is responsible for the oxidative metabolism of FC to farnesal and cysteine. In addition, fcly mutants with quantitative decreases in FC lyase activity exhibit an enhanced response to ABA. However, the enzymological properties of the FCLY-encoded enzyme and its precise role in ABA signaling remain unclear. Here, we show that recombinant Arabidopsis FC lyase expressed in insect cells exhibits high selectivity for FC as a substrate and requires FAD and molecular oxygen for activity. Arabidopsis FC lyase is also shown to undergo post-translational N-glycosylation. FC, which is a competitive inhibitor of isoprenylcysteine methyltransferase (ICMT), accumulates in fcly mutants. Moreover, the enhanced response of fcly mutants to ABA is reversed by ICMT overexpression. These observations support the hypothesis that the ABA hypersensitive phenotype of fcly plants is the result of FC accumulation and inhibition of ICMT.
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Affiliation(s)
- David H. Huizinga
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Ryan Denton
- Department of Chemistry, Indiana University-Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, IN 46202, USA
| | - Kelly G. Koehler
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Ashley Tomasello
- Department of Chemistry, The College of New Jersey, 2000 Pennington Road, Ewing, NJ 08628, USA
| | - Lyndsay Wood
- Department of Chemistry, The College of New Jersey, 2000 Pennington Road, Ewing, NJ 08628, USA
| | - Stephanie E. Sen
- Department of Chemistry, The College of New Jersey, 2000 Pennington Road, Ewing, NJ 08628, USA
| | - Dring N. Crowell
- Department of Biological Sciences, Idaho State University, 650 Memorial Drive, Pocatello, ID 83209, USA
- To whom correspondence should be addressed. E-mail , fax 208-282-4570, tel. 208-282-3171
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Agee AE, Surpin M, Sohn EJ, Girke T, Rosado A, Kram BW, Carter C, Wentzell AM, Kliebenstein DJ, Jin HC, Park OK, Jin H, Hicks GR, Raikhel NV. MODIFIED VACUOLE PHENOTYPE1 is an Arabidopsis myrosinase-associated protein involved in endomembrane protein trafficking. PLANT PHYSIOLOGY 2010; 152:120-32. [PMID: 19880612 PMCID: PMC2799351 DOI: 10.1104/pp.109.145078] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We identified an Arabidopsis (Arabidopsis thaliana) ethyl methanesulfonate mutant, modified vacuole phenotype1-1 (mvp1-1), in a fluorescent confocal microscopy screen for plants with mislocalization of a green fluorescent protein-delta tonoplast intrinsic protein fusion. The mvp1-1 mutant displayed static perinuclear aggregates of the reporter protein. mvp1 mutants also exhibited a number of vacuole-related phenotypes, as demonstrated by defects in growth, utilization of stored carbon, gravitropic response, salt sensitivity, and specific susceptibility to the fungal necrotroph Alternaria brassicicola. Similarly, crosses with other endomembrane marker fusions identified mislocalization to aggregate structures, indicating a general defect in protein trafficking. Map-based cloning showed that the mvp1-1 mutation altered a gene encoding a putative myrosinase-associated protein, and glutathione S-transferase pull-down assays demonstrated that MVP1 interacted specifically with the Arabidopsis myrosinase protein, THIOGLUCOSIDE GLUCOHYDROLASE2 (TGG2), but not TGG1. Moreover, the mvp1-1 mutant showed increased nitrile production during glucosinolate hydrolysis, suggesting that MVP1 may play a role in modulation of myrosinase activity. We propose that MVP1 is a myrosinase-associated protein that functions, in part, to correctly localize the myrosinase TGG2 and prevent inappropriate glucosinolate hydrolysis that could generate cytotoxic molecules.
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Barkla BJ, Vera-Estrella R, Hernández-Coronado M, Pantoja O. Quantitative proteomics of the tonoplast reveals a role for glycolytic enzymes in salt tolerance. THE PLANT CELL 2009; 21:4044-58. [PMID: 20028841 PMCID: PMC2814500 DOI: 10.1105/tpc.109.069211] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 11/20/2009] [Accepted: 11/24/2009] [Indexed: 05/18/2023]
Abstract
To examine the role of the tonoplast in plant salt tolerance and identify proteins involved in the regulation of transporters for vacuolar Na(+) sequestration, we exploited a targeted quantitative proteomics approach. Two-dimensional differential in-gel electrophoresis analysis of free flow zonal electrophoresis separated tonoplast fractions from control, and salt-treated Mesembryanthemum crystallinum plants revealed the membrane association of glycolytic enzymes aldolase and enolase, along with subunits of the vacuolar H(+)-ATPase V-ATPase. Protein blot analysis confirmed coordinated salt regulation of these proteins, and chaotrope treatment indicated a strong tonoplast association. Reciprocal coimmunoprecipitation studies revealed that the glycolytic enzymes interacted with the V-ATPase subunit B VHA-B, and aldolase was shown to stimulate V-ATPase activity in vitro by increasing the affinity for ATP. To investigate a physiological role for this association, the Arabidopsis thaliana cytoplasmic enolase mutant, los2, was characterized. These plants were salt sensitive, and there was a specific reduction in enolase abundance in the tonoplast from salt-treated plants. Moreover, tonoplast isolated from mutant plants showed an impaired ability for aldolase stimulation of V-ATPase hydrolytic activity. The association of glycolytic proteins with the tonoplast may not only channel ATP to the V-ATPase, but also directly upregulate H(+)-pump activity.
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Affiliation(s)
- Bronwyn J Barkla
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Colonia Miraval, Cuernavaca, Morelos, Mexico.
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Hamaji K, Nagira M, Yoshida K, Ohnishi M, Oda Y, Uemura T, Goh T, Sato MH, Morita MT, Tasaka M, Hasezawa SI, Nakano A, Hara-Nishimura I, Maeshima M, Fukaki H, Mimura T. Dynamic aspects of ion accumulation by vesicle traffic under salt stress in Arabidopsis. PLANT & CELL PHYSIOLOGY 2009; 50:2023-33. [PMID: 19880402 DOI: 10.1093/pcp/pcp143] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The intracellular membrane dynamics of Arabidopsis cells under high salt treatment were investigated. When Arabidopsis was treated with high levels of NaCl in hydroponic culture, root tip cells showed rapid changes in the vacuolar volume, a decrease in the number of small acid compartments, active movement of vesicles and accumulation of Na(+) both in the central vacuole and in the vesicles around the main vacuole observed with the Na(+)-dependent fluorescence of Sodium Green. Detailed observation of Arabidopsis suspension-cultured cells under high salt treatment showed a similar pattern of response to that observed in root tip cells. Immunostaining of suspension-cultured cells with antibodies against AtNHX1 clearly showed the occurrence of dotted fluorescence in the cytoplasm only under salt treatment. We also confirmed the existence of AtNHX1 in the vacuolar membrane isolated from suspension-cultured cells with immunofluorescence. Knockout of the vacuolar Q(a)-SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein VAM3/SYP22 caused an increase in salt tolerance. In mutant plants, the distribution of Na(+) between roots and shoots differed from that of wild-type plants, with Na(+) accumulating more in roots and less in the shoots of the mutant plants. The role of vesicle traffic under salt stress is discussed.
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Affiliation(s)
- Kohei Hamaji
- Graduate School of Science, Kobe University, Nada-ku, Kobe, 657-8501, Japan
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Nakanishi N, Rahman MM, Sakamoto Y, Takigami T, Kobayashi K, Hori H, Hase T, Park SY, Tsubaki M. Importance of the conserved lysine 83 residue of Zea mays cytochrome b(561) for ascorbate-specific transmembrane electron transfer as revealed by site-directed mutagenesis studies. Biochemistry 2009; 48:10665-78. [PMID: 19803484 DOI: 10.1021/bi9010682] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cytochromes b(561), a novel class of transmembrane electron transport proteins residing in a large variety of eukaryotic cells, have a number of common structural features including six hydrophobic transmembrane alpha-helices and two heme ligation sites. We found that recombinant Zea mays cytochrome b(561) obtained by a heterologous expression system using yeast Pichia pastoris cells could utilize the ascorbate/mondehydroascorbate radical as a physiological electron donor/acceptor. We found further that a concerted proton/electron transfer mechanism might be operative in Z. mays cytochrome b(561) as well upon the electron acceptance from ascorbate to the cytosolic heme center. The well-conserved Lys(83) residue in a cytosolic loop was found to have a very important role(s) for the binding of ascorbate and the succeeding electron transfer via electrostatic interactions based on the analyses of three site-specific mutants, K83A, K83E, and K83D. Further, unusual behavior of the K83A mutant in pulse radiolysis experiments indicated that Lys(83) might also be responsible for the intramolecular electron transfer to the intravesicular heme. On the other hand, pulse radiolysis experiments on two site-specific mutants, S118A and W122A, for the well-conserved residues in the putative monodehydroascorbate radical binding site showed that their electron transfer activities to the monodehydroascorbate radical were very similar to those of the wild-type protein, indicating that Ser(118) and Trp(122) do not have major roles for the redox events on the intravesicular side.
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Affiliation(s)
- Nobuyuki Nakanishi
- Department of Molecular Science and Material Engineering, Graduate School of Science and Technology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan
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Lingard MJ, Bartel B. Arabidopsis LON2 is necessary for peroxisomal function and sustained matrix protein import. PLANT PHYSIOLOGY 2009; 151:1354-65. [PMID: 19748917 PMCID: PMC2773057 DOI: 10.1104/pp.109.142505] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 09/07/2009] [Indexed: 05/19/2023]
Abstract
Relatively little is known about the small subset of peroxisomal proteins with predicted protease activity. Here, we report that the peroxisomal LON2 (At5g47040) protease facilitates matrix protein import into Arabidopsis (Arabidopsis thaliana) peroxisomes. We identified T-DNA insertion alleles disrupted in five of the nine confirmed or predicted peroxisomal proteases and found only two-lon2 and deg15, a mutant defective in the previously described PTS2-processing protease (DEG15/At1g28320)-with phenotypes suggestive of peroxisome metabolism defects. Both lon2 and deg15 mutants were mildly resistant to the inhibitory effects of indole-3-butyric acid (IBA) on root elongation, but only lon2 mutants were resistant to the stimulatory effects of IBA on lateral root production or displayed Suc dependence during seedling growth. lon2 mutants displayed defects in removing the type 2 peroxisome targeting signal (PTS2) from peroxisomal malate dehydrogenase and reduced accumulation of 3-ketoacyl-CoA thiolase, another PTS2-containing protein; both defects were not apparent upon germination but appeared in 5- to 8-d-old seedlings. In lon2 cotyledon cells, matrix proteins were localized to peroxisomes in 4-d-old seedlings but mislocalized to the cytosol in 8-d-old seedlings. Moreover, a PTS2-GFP reporter sorted to peroxisomes in lon2 root tip cells but was largely cytosolic in more mature root cells. Our results indicate that LON2 is needed for sustained matrix protein import into peroxisomes. The delayed onset of matrix protein sorting defects may account for the relatively weak Suc dependence following germination, moderate IBA-resistant primary root elongation, and severe defects in IBA-induced lateral root formation observed in lon2 mutants.
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Schneider T, Schellenberg M, Meyer S, Keller F, Gehrig P, Riedel K, Lee Y, Eberl L, Martinoia E. Quantitative detection of changes in the leaf-mesophyll tonoplast proteome in dependency of a cadmium exposure of barley (Hordeum vulgare L.) plants. Proteomics 2009; 9:2668-77. [PMID: 19391183 DOI: 10.1002/pmic.200800806] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Although the vacuole is the most important final store for toxic heavy metals like cadmium (Cd(2+)), our knowledge on how they are transported into the vacuole is still insufficient. It has been suggested that Cd(2+) can be transported as phytochelatin-Cd(2+) by an unknown ABC transporter or in exchange with protons by cation/proton exchanger (CAX) transporters. To unravel the contribution of vacuolar transporters to Cd(2+) detoxification, a quantitative proteomics approach was performed. Highly purified vacuoles were isolated from barley plants grown under minus, low (20 microM), and high (200 microM) Cd(2+ )conditions and protein levels of the obtained tonoplast samples were analyzed using isobaric tag for relative and absolute quantitation (iTRAQ). Although 56 vacuolar transporter proteins were identified, only a few were differentially expressed. Under low-Cd(2+) conditions, an inorganic pyrophosphatase and a gamma-tonoplast intrinsic protein (gamma-TIP) were up-regulated, indicating changes in energization and water fluxes. In addition, the protein ratio of a CAX1a and a natural resistance-associated macrophage protein (NRAMP), responsible for vacuolar Fe(2+) export was increased. CAX1a might play a role in vacuolar Cd(2+) transport. An increase in NRAMP activity leads to a higher cytosolic Fe(2+) concentration, which may prevent the exchange of Fe(2+) by toxic Cd(2+). Additionally, an ABC transporter homolog to AtMRP3 showed up-regulation. Under high Cd(2+) conditions, the plant response was more specific. Only a protein homologous to AtMRP3 that showed already a response under low Cd(2+) conditions, was up-regulated. Interestingly, AtMRP3 is able to partially rescue a Cd(2+)-sensitive yeast mutant. The identified transporters are good candidates for further investigation of their roles in Cd(2+) detoxification.
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Affiliation(s)
- Thomas Schneider
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, Zurich, Switzerland.
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Silva P, Gerós H. Regulation by salt of vacuolar H+-ATPase and H+-pyrophosphatase activities and Na+/H+ exchange. PLANT SIGNALING & BEHAVIOR 2009; 4:718-26. [PMID: 19820346 PMCID: PMC2801382 DOI: 10.4161/psb.4.8.9236] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Accepted: 06/09/2009] [Indexed: 05/20/2023]
Abstract
Over the last decades several efforts have been carried out to determine the mechanisms of salt homeostasis in plants and, more recently, to identify genes implicated in salt tolerance, with some plants being successfully genetically engineered to improve resistance to salt. It is well established that the efficient exclusion of Na(+) excess from the cytoplasm and vacuolar Na(+) accumulation are the most important steps towards the maintenance of ion homeostasis inside the cell. Therefore, the vacuole of plant cells plays a pivotal role in the storage of salt. After the identification of the vacuolar Na(+)/H(+) antiporter Nhx1 in Saccharomyces cerevisiae, the first plant Na(+)/H(+) antiporter, AtNHX1, was isolated from Arabidopsis and its overexpression resulted in plants exhibiting increased salt tolerance. Also, the identification of the plasma membrane Na(+)/H(+) exchanger SOS1 and how it is regulated by a protein kinase SOS2 and a calcium binding protein SOS3 were great achievements in the understanding of plant salt resistance. Both tonoplast and plasma membrane antiporters exclude Na+ from the cytosol driven by the proton-motive force generated by the plasma membrane H(+)-ATPase and by the vacuolar membrane H(+)-ATPase and H(+)-pyrophosphatase and it has been shown that the activity of these proteins responds to salinity. In this review we focus on the transcriptional and post-transcriptional regulation by salt of tonoplast proton pumps and Na(+)/H(+) exchangers and on the signalling pathways involved in salt sensing.
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Affiliation(s)
- Paulo Silva
- Centro de Investigação e de Tecnologias Agro-Ambientais e Biológicas (CITAB); Portugal
- Departamento de Biologia; Universidade do Minho; Braga, Portugal
| | - Hernâni Gerós
- Centro de Investigação e de Tecnologias Agro-Ambientais e Biológicas (CITAB); Portugal
- Departamento de Biologia; Universidade do Minho; Braga, Portugal
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Preger V, Tango N, Marchand C, Lemaire SD, Carbonera D, Di Valentin M, Costa A, Pupillo P, Trost P. Auxin-responsive genes AIR12 code for a new family of plasma membrane b-type cytochromes specific to flowering plants. PLANT PHYSIOLOGY 2009; 150:606-20. [PMID: 19386804 PMCID: PMC2689961 DOI: 10.1104/pp.109.139170] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 04/15/2009] [Indexed: 05/05/2023]
Abstract
We report here on the identification of the major plasma membrane (PM) ascorbate-reducible b-type cytochrome of bean (Phaseolus vulgaris) and soybean (Glycine max) hypocotyls as orthologs of Arabidopsis (Arabidopsis thaliana) AIR12 (for auxin induced in root cultures). Soybean AIR12, which is glycosylated and glycosylphosphatidylinositol-anchored to the external side of the PM in vivo, was expressed in Pichia pastoris in a recombinant form, lacking the glycosylphosphatidylinositol modification signal and purified from the culture medium. Recombinant AIR12 is a soluble protein predicted to fold into a beta-sandwich domain and belonging to the DOMON (for dopamine beta-monooxygenase N terminus) domain superfamily. It is shown to be a b-type cytochrome with a symmetrical alpha-band at 561 nm, fully reduced by ascorbate, and fully oxidized by monodehydroascorbate radical. AIR12 is a high-potential cytochrome b showing a wide bimodal dependence from the redox potential between +80 mV and +300 mV. Optical absorption and electron paramagnetic resonance analysis indicate that AIR12 binds a single, highly axial low-spin heme, likely coordinated by methionine-91 and histidine-76, which are strongly conserved in AIR12 sequences. Phylogenetic analyses reveal that the auxin-responsive genes AIR12 represent a new family of PM b-type cytochromes specific to flowering plants. Circumstantial evidence suggests that AIR12 may interact with other redox partners within the PM to constitute a redox link between cytoplasm and apoplast.
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Affiliation(s)
- Valeria Preger
- Laboratory of Molecular Plant Physiology, Department of Experimental Evolutionary Biology, University of Bologna, Bologna 40126, Italy.
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72
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Paungfoo-Lonhienne C, Schenk PM, Lonhienne TGA, Brackin R, Meier S, Rentsch D, Schmidt S. Nitrogen affects cluster root formation and expression of putative peptide transporters. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:2665-76. [PMID: 19380419 PMCID: PMC2692012 DOI: 10.1093/jxb/erp111] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 03/10/2009] [Accepted: 03/16/2009] [Indexed: 05/18/2023]
Abstract
Non-mycorrhizal Hakea actites (Proteaceae) grows in heathland where organic nitrogen (ON) dominates the soil nitrogen (N) pool. Hakea actites uses ON for growth, but the role of cluster roots in ON acquisition is unknown. The aim of the present study was to ascertain how N form and concentration affect cluster root formation and expression of peptide transporters. Hydroponically grown plants produced most biomass with low molecular weight ON>inorganic N>high molecular weight ON, while cluster roots were formed in the order no-N>ON>inorganic N. Intact dipeptide was transported into roots and metabolized, suggesting a role for the peptide transporter (PTR) for uptake and transport of peptides. HaPTR4, a member of subgroup II of the NRT1/PTR transporter family, which contains most characterized di- and tripeptide transporters in plants, facilitated transport of di- and tripeptides when expressed in yeast. No transport activity was demonstrated for HaPTR5 and HaPTR12, most similar to less well characterized transporters in subgroup III. The results provide further evidence that subgroup II of the NRT1/PTR family contains functional di- and tripeptide transporters. Green fluorescent protein fusion proteins of HaPTR4 and HaPTR12 localized to tonoplast, and plasma- and endomembranes, respectively, while HaPTR5 localized to vesicles of unknown identity. Grown in heathland or hydroponic culture with limiting N supply or starved of nutrients, HaPTR genes had the highest expression in cluster roots and non-cluster roots, and leaf expression increased upon re-supply of ON. It is concluded that formation of cluster roots and expression of PTR are regulated in response to N supply.
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73
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Chanda A, Roze LV, Pastor A, Frame MK, Linz JE. Purification of a vesicle-vacuole fraction functionally linked to aflatoxin synthesis in Aspergillus parasiticus. J Microbiol Methods 2009; 78:28-33. [PMID: 19358865 DOI: 10.1016/j.mimet.2009.03.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 03/31/2009] [Accepted: 03/31/2009] [Indexed: 10/20/2022]
Abstract
Current studies in our laboratory demonstrate a functional link between vesicles, vacuoles and aflatoxin biosynthesis in the filamentous fungus, Aspergillus parasiticus. Under aflatoxin inducing conditions in liquid yeast-extract sucrose medium, A. parasiticus undergoes a shift from vacuole biogenesis to accumulation of an enhanced number of vesicles which exhibit significant heterogeneity in size and density. As a first step in conducting a detailed analysis of the role of these organelles in aflatoxin synthesis, we developed a novel method to purify the vesicle and vacuole fraction using protoplasts prepared from cells harvested during aflatoxin synthesis. The method includes the following steps: 1] preparation of protoplasts from mycelia grown for 36 h under aflatoxin inducing conditions; 2] release of vesicles and vacuoles from purified protoplasts in the presence of Triton X-100; and 3] fractionation of the vesicles and vacuoles using a "one-step high density cushion". The vesicle-vacuole fraction showed a 35 fold enrichment in alpha-mannosidase activity (vacuole marker) and non-detectable succinate dehydrogenase and lactate dehydrogenase activities (mitochondrial and cytoplasmic markers, respectively). Confocal laser scanning microscopy with the vacuole dyes MDY-64 and CMAC demonstrated that the fraction contained pure vesicles and vacuoles and was devoid of membranous debris. Transmission electron microscopy (TEM) confirmed that no mitochondria or unbroken protoplasts contaminated the purified fraction. The purified organelles exhibited significant size heterogeneity with a range of sizes similar to that observed in whole cells and protoplasts.
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Affiliation(s)
- Anindya Chanda
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA
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74
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Shoji T, Inai K, Yazaki Y, Sato Y, Takase H, Shitan N, Yazaki K, Goto Y, Toyooka K, Matsuoka K, Hashimoto T. Multidrug and toxic compound extrusion-type transporters implicated in vacuolar sequestration of nicotine in tobacco roots. PLANT PHYSIOLOGY 2009; 149:708-18. [PMID: 19098091 PMCID: PMC2633862 DOI: 10.1104/pp.108.132811] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Accepted: 12/16/2008] [Indexed: 05/17/2023]
Abstract
Nicotine is a major alkaloid accumulating in the vacuole of tobacco (Nicotiana tabacum), but the transporters involved in the vacuolar sequestration are not known. We here report that tobacco genes (NtMATE1 and NtMATE2) encoding transporters of the multidrug and toxic compound extrusion (MATE) family are coordinately regulated with structural genes for nicotine biosynthesis in the root, with respect to spatial expression patterns, regulation by NIC regulatory loci, and induction by methyl jasmonate. Subcellular fractionation, immunogold electron microscopy, and expression of a green fluorescent protein fusion protein all suggested that these transporters are localized to the vacuolar membrane. Reduced expression of the transporters rendered tobacco plants more sensitive to the application of nicotine. In contrast, overexpression of NtMATE1 in cultured tobacco cells induced strong acidification of the cytoplasm after jasmonate elicitation or after the addition of nicotine under nonelicited conditions. Expression of NtMATE1 in yeast (Saccharomyces cerevisiae) cells compromised the accumulation of exogenously supplied nicotine into the yeast cells. The results imply that these MATE-type proteins transport tobacco alkaloids from the cytosol into the vacuole in exchange for protons in alkaloid-synthesizing root cells.
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Affiliation(s)
- Tsubasa Shoji
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
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75
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Morel M, Crouzet J, Gravot A, Auroy P, Leonhardt N, Vavasseur A, Richaud P. AtHMA3, a P1B-ATPase allowing Cd/Zn/Co/Pb vacuolar storage in Arabidopsis. PLANT PHYSIOLOGY 2009; 149:894-904. [PMID: 19036834 PMCID: PMC2633814 DOI: 10.1104/pp.108.130294] [Citation(s) in RCA: 363] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Accepted: 11/21/2008] [Indexed: 05/18/2023]
Abstract
The Arabidopsis (Arabidopsis thaliana) Heavy Metal Associated3 (AtHMA3) protein belongs to the P1B-2 subgroup of the P-type ATPase family, which is involved in heavy metal transport. In a previous study, we have shown, using heterologous expression in the yeast Saccharomyces cerevisiae, that in the presence of toxic metals, AtHMA3 was able to phenotypically complement the cadmium/lead (Cd/Pb)-hypersensitive strain ycf1 but not the zinc (Zn)-hypersensitive strain zrc1. In this study, we demonstrate that AtHMA3 in planta is located in the vacuolar membrane, with a high expression level in guard cells, hydathodes, vascular tissues, and the root apex. Confocal imaging in the presence of the Zn/Cd fluorescent probe BTC-5N revealed that AtHMA3 participates in the vacuolar storage of Cd. A T-DNA insertional mutant was found more sensitive to Zn and Cd. Conversely, ectopic overexpression of AtHMA3 improved plant tolerance to Cd, cobalt, Pb, and Zn; Cd accumulation increased by about 2- to 3-fold in plants overexpressing AtHMA3 compared with wild-type plants. Thus, AtHMA3 likely plays a role in the detoxification of biological (Zn) and nonbiological (Cd, cobalt, and Pb) heavy metals by participating in their vacuolar sequestration, an original function for a P1B-2 ATPase in a multicellular eukaryote.
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Affiliation(s)
- Mélanie Morel
- l'Energie Atomique, DSV, IBEB, Lab Echanges Membran and Signalisation, Saint-Paul-lez-Durance F-13108, France
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76
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Endler A, Reiland S, Gerrits B, Schmidt UG, Baginsky S, Martinoia E. In vivo phosphorylation sites of barley tonoplast proteins identified by a phosphoproteomic approach. Proteomics 2009; 9:310-21. [DOI: 10.1002/pmic.200800323] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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77
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Whiteman SA, Serazetdinova L, Jones AME, Sanders D, Rathjen J, Peck SC, Maathuis FJM. Identification of novel proteins and phosphorylation sites in a tonoplast enriched membrane fraction of Arabidopsis thaliana. Proteomics 2008; 8:3536-47. [PMID: 18686298 DOI: 10.1002/pmic.200701104] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plant vacuoles play essential roles in many physiological processes, particularly in mineral nutrition, turgor provision and cellular signalling. The vacuolar membrane, the tonoplast, contains many membrane transporters that are critical in the execution of these processes. However, although increasing knowledge is available about the identity of proteins involved in these processes very little is known about the regulation of tonoplast transporters. By studying the phosphoproteome of tonoplast-enriched membranes, we identified 66 phosphorylation sites on 58 membrane proteins. Amongst these, 31 sites were identified in 28 membrane transporters of various families including tonoplast anion transporters of the CLC family, potassium transporters of the KUP family, tonoplast sugar transporters and ABC transporters. In a number of cases, the detected sites were well conserved across isoforms of one family pointing to common mechanisms of regulation. In other cases, isoform-unique sites were present, suggesting regulatory mechanisms tailored to the function of individual proteins. These results provide the basis for future studies to elucidate the mechanistic regulation of tonoplast membrane transporters.
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78
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Piotrowski M. Primary or secondary? Versatile nitrilases in plant metabolism. PHYTOCHEMISTRY 2008; 69:2655-67. [PMID: 18842274 DOI: 10.1016/j.phytochem.2008.08.020] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Accepted: 08/26/2008] [Indexed: 05/08/2023]
Abstract
The potential of plant nitrilases to convert indole-3-acetonitrile into the plant growth hormone indole-3-acetic acid has earned them the interim title of "key enzyme in auxin biosynthesis". Although not widely recognized, this view has changed considerably in the last few years. Recent work on plant nitrilases has shown them to be involved in the process of cyanide detoxification, in the catabolism of cyanogenic glycosides and presumably in the catabolism of glucosinolates. All plants possess at least one nitrilase that is homologous to the nitrilase 4 isoform of Arabidopsis thaliana. The general function of these nitrilases lies in the process of cyanide detoxification, in which they convert the intermediate detoxification product beta-cyanoalanine into asparagine, aspartic acid and ammonia. Cyanide is a metabolic by-product in biosynthesis of the plant hormone ethylene, but it may also be released from cyanogenic glycosides, which are present in a large number of plants. In Sorghum bicolor, an additional nitrilase isoform has been identified, which can directly use a catabolic intermediate of the cyanogenic glycoside dhurrin, thus enabling the plant to metabolize its cyanogenic glycoside without releasing cyanide. In the Brassicaceae, a family of nitrilases has evolved, the members of which are able to hydrolyze catabolic products of glucosinolates, the predominant secondary metabolites of these plants. Thus, the general theme of nitrilase function in plants is detoxification and nitrogen recycling, since the valuable nitrogen of the nitrile group is recovered in the useful metabolites asparagine or ammonia. Taken together, a picture emerges in which plant nitrilases have versatile functions in plant metabolism, whereas their importance for auxin biosynthesis seems to be minor.
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Affiliation(s)
- Markus Piotrowski
- Department of Plant Physiology, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany.
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79
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Carpentier SC, Panis B, Vertommen A, Swennen R, Sergeant K, Renaut J, Laukens K, Witters E, Samyn B, Devreese B. Proteome analysis of non-model plants: a challenging but powerful approach. MASS SPECTROMETRY REVIEWS 2008; 27:354-77. [PMID: 18381744 DOI: 10.1002/mas.20170] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Biological research has focused in the past on model organisms and most of the functional genomics studies in the field of plant sciences are still performed on model species or species that are characterized to a great extent. However, numerous non-model plants are essential as food, feed, or energy resource. Some features and processes are unique to these plant species or families and cannot be approached via a model plant. The power of all proteomic and transcriptomic methods, that is, high-throughput identification of candidate gene products, tends to be lost in non-model species due to the lack of genomic information or due to the sequence divergence to a related model organism. Nevertheless, a proteomics approach has a great potential to study non-model species. This work reviews non-model plants from a proteomic angle and provides an outline of the problems encountered when initiating the proteome analysis of a non-model organism. The review tackles problems associated with (i) sample preparation, (ii) the analysis and interpretation of a complex data set, (iii) the protein identification via MS, and (iv) data management and integration. We will illustrate the power of 2DE for non-model plants in combination with multivariate data analysis and MS/MS identification and will evaluate possible alternatives.
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80
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Zhang J, Ma H, Feng J, Zeng L, Wang Z, Chen S. Grape berry plasma membrane proteome analysis and its differential expression during ripening. JOURNAL OF EXPERIMENTAL BOTANY 2008; 59:2979-90. [PMID: 18550598 DOI: 10.1093/jxb/ern156] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
High purity berry plasma membranes (PMs) of Vitis vinifera L. cv. Cabernet Sauvignon were isolated by two-phase partitioning of microsome fractions at different stages of berry ripening. PM proteins resolvable by the detergent cocktail of CHAPS and ASB-14 were separated by two-dimensional electrophoresis. A total of 119 protein spots from pre-véraison berry PMs on 2-D gels detected with silver staining were subjected to MALDI-TOF mass spectrometry analysis. Sixty-two spots were identified as putative PM proteins, with 1-6 predicted transmembrane helices, including true PM proteins such as ATP synthase, ABC transporters, and GTP-binding proteins reported in plants. They were then grouped into eight functional categories, mainly involved in transport, metabolism, signal transduction, and protein synthesis. Another 11 spots were identified as proteins of unknown function. The véraison and post-véraison samples stained 98 and 86 spots on the gels, respectively. During the berry ripening process, total PM protein content gradually decreased. Among all identified proteins, 12 showed significant differences in terms of their relative abundance. Increasing ubiquitin proteolysis and cytoskeleton proteins were observed from pre-véraison to post-véraison. Zeatin O-glucosyltransferase peaked at véraison, while ubiquitin-conjugating enzyme E2-21 was down-regulated at this stage. This proteome research provides the first information on PM protein characterization during the grape berry ripening process.
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Affiliation(s)
- Jiangwei Zhang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
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81
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Seidel T, Schnitzer D, Golldack D, Sauer M, Dietz KJ. Organelle-specific isoenzymes of plant V-ATPase as revealed by in vivo-FRET analysis. BMC Cell Biol 2008; 9:28. [PMID: 18507826 PMCID: PMC2424043 DOI: 10.1186/1471-2121-9-28] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Accepted: 05/28/2008] [Indexed: 11/10/2022] Open
Abstract
Background The V-ATPase (VHA) is a protein complex of 13 different VHA-subunits. It functions as an ATP driven rotary-motor that electrogenically translocates H+ into endomembrane compartments. In Arabidopsis thaliana V-ATPase is encoded by 23 genes posing the question of specific versus redundant function of multigene encoded isoforms. Results The transmembrane topology and stoichiometry of the proteolipid VHA-c" as well as the stoichiometry of the membrane integral subunit VHA-e within the V-ATPase complex were investigated by in vivo fluorescence resonance energy transfer (FRET). VHA-c", VHA-e1 and VHA-e2, VHA-a, VHA-c3, truncated variants of VHA-c3 and a chimeric VHA-c/VHA-c" hybrid were fused to cyan (CFP) and yellow fluorescent protein (YFP), respectively. The constructs were employed for transfection experiments with Arabidopsis thaliana mesophyll protoplasts. Subcellular localization and FRET analysis by confocal laser scanning microscopy (CLSM) demonstrated that (i.) the N- and C-termini of VHA-c" are localised in the vacuolar lumen, (ii.) one copy of VHA-c" is present within the VHA-complex, and (iii.) VHA-c" is localised at the ER and associated Golgi bodies. (iv.) A similar localisation was observed for VHA-e2, whereas (v.) the subcellular localisation of VHA-e1 indicated the trans Golgi network (TGN)-specifity of this subunit. Conclusion The plant proteolipid ring is a highly flexible protein subcomplex, tolerating the incorporation of truncated and hybrid proteolipid subunits, respectively. Whereas the membrane integral subunit VHA-e is present in two copies within the complex, the proteolipid subunit VHA-c" takes part in complex formation with only one copy. However, neither VHA-c" isoform 1 nor any of the two VHA-e isoforms were identified at the tonoplast. This suggest a function in endomembrane specific VHA-assembly or targeting rather than proton transport.
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Affiliation(s)
- Thorsten Seidel
- Department of Biochemistry and Physiology of Plants, W5, University of Bielefeld, 33501 Bielefeld, Germany.
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82
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Schneider S, Beyhl D, Hedrich R, Sauer N. Functional and physiological characterization of Arabidopsis INOSITOL TRANSPORTER1, a novel tonoplast-localized transporter for myo-inositol. THE PLANT CELL 2008; 20:1073-87. [PMID: 18441213 PMCID: PMC2390729 DOI: 10.1105/tpc.107.055632] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Arabidopsis thaliana INOSITOL TRANSPORTER1 (INT1) is a member of a small gene family with only three more genes (INT2 to INT4). INT2 and INT4 were shown to encode plasma membrane-localized transporters for different inositol epimers, and INT3 was characterized as a pseudogene. Here, we present the functional and physiological characterization of the INT1 protein, analyses of the tissue-specific expression of the INT1 gene, and analyses of phenotypic differences observed between wild-type plants and mutant lines carrying the int1.1 and int1.2 alleles. INT1 is a ubiquitously expressed gene, and Arabidopsis lines with T-DNA insertions in INT1 showed increased intracellular myo-inositol concentrations and reduced root growth. In Arabidopsis, tobacco (Nicotiana tabacum), and Saccharomyces cerevisiae, fusions of the green fluorescent protein to the C terminus of INT1 were targeted to the tonoplast membranes. Finally, patch-clamp analyses were performed on vacuoles from wild-type plants and from both int1 mutant lines to study the transport properties of INT1 at the tonoplast. In summary, the presented molecular, physiological, and functional studies demonstrate that INT1 is a tonoplast-localized H(+)/inositol symporter that mediates the efflux of inositol that is generated during the degradation of inositol-containing compounds in the vacuolar lumen.
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Affiliation(s)
- Sabine Schneider
- Molekulare Pflanzenphysiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
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83
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Mano S, Miwa T, Nishikawa SI, Mimura T, Nishimura M. The plant organelles database (PODB): a collection of visualized plant organelles and protocols for plant organelle research. Nucleic Acids Res 2008; 36:D929-37. [PMID: 17932059 PMCID: PMC2238956 DOI: 10.1093/nar/gkm789] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 09/14/2007] [Accepted: 09/17/2007] [Indexed: 11/12/2022] Open
Abstract
The plant organelles database (PODB; http://podb.nibb.ac.jp/Organellome) was built to promote a comprehensive understanding of organelle dynamics, including organelle function, biogenesis, differentiation, movement and interactions with other organelles. This database consists of three individual parts, the organellome database, the functional analysis database and external links to other databases and homepages. The organellome database provides images of various plant organelles that were visualized with fluorescent and nonfluorescent probes in various tissues of several plant species at different developmental stages. The functional analysis database is a collection of protocols for plant organelle research. External links give access primarily to other databases and Web pages with information on transcriptomes and proteomes. All the data and protocols in the organellome database and the functional analysis database are populated by direct submission of experimentally determined data from plant researchers and can be freely downloaded. Our database promotes the exchange of information between plant organelle researchers for the comprehensive study of the organelle dynamics that support integrated functions in higher plants. We would also appreciate contributions of data and protocols from all plant researchers to maximize the usefulness of the database.
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Affiliation(s)
- Shoji Mano
- Department of Cell Biology, National Institute for Basic Biology, Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, Computer Laboratory, National Institute for Basic Biology, Okazaki 444-8585, Graduate School of Science, Nagoya University, Nagoya 464-8602 and Department of Biology, Faculty of Science, Kobe University, Kobe 657-8501, Japan
| | - Tomoki Miwa
- Department of Cell Biology, National Institute for Basic Biology, Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, Computer Laboratory, National Institute for Basic Biology, Okazaki 444-8585, Graduate School of Science, Nagoya University, Nagoya 464-8602 and Department of Biology, Faculty of Science, Kobe University, Kobe 657-8501, Japan
| | - Shuh-ichi Nishikawa
- Department of Cell Biology, National Institute for Basic Biology, Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, Computer Laboratory, National Institute for Basic Biology, Okazaki 444-8585, Graduate School of Science, Nagoya University, Nagoya 464-8602 and Department of Biology, Faculty of Science, Kobe University, Kobe 657-8501, Japan
| | - Tetsuro Mimura
- Department of Cell Biology, National Institute for Basic Biology, Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, Computer Laboratory, National Institute for Basic Biology, Okazaki 444-8585, Graduate School of Science, Nagoya University, Nagoya 464-8602 and Department of Biology, Faculty of Science, Kobe University, Kobe 657-8501, Japan
| | - Mikio Nishimura
- Department of Cell Biology, National Institute for Basic Biology, Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, Computer Laboratory, National Institute for Basic Biology, Okazaki 444-8585, Graduate School of Science, Nagoya University, Nagoya 464-8602 and Department of Biology, Faculty of Science, Kobe University, Kobe 657-8501, Japan
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Strasser R, Bondili JS, Schoberer J, Svoboda B, Liebminger E, Glössl J, Altmann F, Steinkellner H, Mach L. Enzymatic properties and subcellular localization of Arabidopsis beta-N-acetylhexosaminidases. PLANT PHYSIOLOGY 2007; 145:5-16. [PMID: 17644627 PMCID: PMC1976588 DOI: 10.1104/pp.107.101162] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Plant glycoproteins contain substantial amounts of paucimannosidic N-glycans lacking terminal GlcNAc residues at their nonreducing ends. It has been proposed that this is due to the action of beta-hexosaminidases during late stages of N-glycan processing or in the course of N-glycan turnover. We have now cloned the three putative beta-hexosaminidase sequences present in the Arabidopsis (Arabidopsis thaliana) genome. When heterologously expressed as soluble forms in Spodoptera frugiperda cells, the enzymes (termed HEXO1-3) could all hydrolyze the synthetic substrates p-nitrophenyl-2-acetamido-2-deoxy-beta-d-glucopyranoside, p-nitrophenyl-2-acetamido-2-deoxy-beta-d-galactopyranoside, 4-methylumbelliferyl-2-acetamido-2-deoxy-beta-d-glucopyranoside, and 4-methylumbelliferyl-6-sulfo-2-acetamido-2-deoxy-beta-d-glucopyranoside, albeit to a varying extent. HEXO1 to HEXO3 were further able to degrade pyridylaminated chitotriose, whereas pyridylaminated chitobiose was only cleaved by HEXO1. With N-glycan substrates, HEXO1 displayed a much higher specific activity than HEXO2 and HEXO3. Nevertheless, all three enzymes were capable of removing terminal GlcNAc residues from the alpha1,3- and alpha1,6-mannosyl branches of biantennary N-glycans without any strict branch preference. Subcellular localization studies with HEXO-fluorescent protein fusions transiently expressed in Nicotiana benthamiana plants showed that HEXO1 is a vacuolar protein. In contrast, HEXO2 and HEXO3 are mainly located at the plasma membrane. These results indicate that HEXO1 participates in N-glycan trimming in the vacuole, whereas HEXO2 and/or HEXO3 could be responsible for the processing of N-glycans present on secretory glycoproteins.
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Affiliation(s)
- Richard Strasser
- Institute of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Applied Life Sciences, A-1190 Vienna, Austria.
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85
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Jaquinod M, Villiers F, Kieffer-Jaquinod S, Hugouvieux V, Bruley C, Garin J, Bourguignon J. A Proteomics Approach Highlights a Myriad of Transporters in the Arabidopsis thaliana Vacuolar Membrane. PLANT SIGNALING & BEHAVIOR 2007; 2:413-5. [PMID: 19704618 PMCID: PMC2634231 DOI: 10.4161/psb.2.5.4415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Accepted: 05/10/2007] [Indexed: 05/09/2023]
Abstract
To better understand plant vacuolar functions and identify new transporters present on the tonoplast, a proteomic work was initiated on Arabidopsis thaliana. A procedure was developed to prepare highly purified vacuoles from protoplasts isolated from Arabidopsis cell cultures, and a proteomics approach was designed to identify the protein components present in both the membrane and soluble fractions of the vacuoles. This procedure allowed the identification of 650 proteins, 2/3 of which copurify with the hydrophobic membrane fraction and 1/3 with the soluble fraction. With regard to function, only 20% of the proteins identified were previously known to be associated with vacuolar activities.
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Affiliation(s)
- Michel Jaquinod
- Laboratoire d'Etude de la Dynamique des Protéomes Institut de Recherches en Technologies et Sciences pour le Vivant; Commissariat à l'Energie Atomique; Université Joseph Fourier, Grenoble France
| | - Florent Villiers
- Laboratoire de Physiologie Cellulaire Végétale; Institut de Recherches en Technologies et Sciences pour le Vivant; Commissariat à l'Energie Atomique; Université Joseph Fourier, Grenoble France
| | - Sylvie Kieffer-Jaquinod
- Laboratoire d'Etude de la Dynamique des Protéomes Institut de Recherches en Technologies et Sciences pour le Vivant; Commissariat à l'Energie Atomique; Université Joseph Fourier, Grenoble France
| | - Véronique Hugouvieux
- Laboratoire de Physiologie Cellulaire Végétale; Institut de Recherches en Technologies et Sciences pour le Vivant; Commissariat à l'Energie Atomique; Université Joseph Fourier, Grenoble France
| | - Christophe Bruley
- Laboratoire d'Etude de la Dynamique des Protéomes Institut de Recherches en Technologies et Sciences pour le Vivant; Commissariat à l'Energie Atomique; Université Joseph Fourier, Grenoble France
| | - Jérôme Garin
- Laboratoire d'Etude de la Dynamique des Protéomes Institut de Recherches en Technologies et Sciences pour le Vivant; Commissariat à l'Energie Atomique; Université Joseph Fourier, Grenoble France
| | - Jacques Bourguignon
- Laboratoire de Physiologie Cellulaire Végétale; Institut de Recherches en Technologies et Sciences pour le Vivant; Commissariat à l'Energie Atomique; Université Joseph Fourier, Grenoble France
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86
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Schmidt UG, Endler A, Schelbert S, Brunner A, Schnell M, Neuhaus HE, Marty-Mazars D, Marty F, Baginsky S, Martinoia E. Novel tonoplast transporters identified using a proteomic approach with vacuoles isolated from cauliflower buds. PLANT PHYSIOLOGY 2007; 145:216-29. [PMID: 17660356 PMCID: PMC1976570 DOI: 10.1104/pp.107.096917] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Young meristematic plant cells contain a large number of small vacuoles, while the largest part of the vacuome in mature cells is composed by a large central vacuole, occupying 80% to 90% of the cell volume. Thus far, only a limited number of vacuolar membrane proteins have been identified and characterized. The proteomic approach is a powerful tool to identify new vacuolar membrane proteins. To analyze vacuoles from growing tissues we isolated vacuoles from cauliflower (Brassica oleracea) buds, which are constituted by a large amount of small cells but also contain cells in expansion as well as fully expanded cells. Here we show that using purified cauliflower vacuoles and different extraction procedures such as saline, NaOH, acetone, and chloroform/methanol and analyzing the data against the Arabidopsis (Arabidopsis thaliana) database 102 cauliflower integral proteins and 214 peripheral proteins could be identified. The vacuolar pyrophosphatase was the most prominent protein. From the 102 identified proteins 45 proteins were already described. Nine of these, corresponding to 46% of peptides detected, are known vacuolar proteins. We identified 57 proteins (55.9%) containing at least one membrane spanning domain with unknown subcellular localization. A comparison of the newly identified proteins with expression profiles from in silico data revealed that most of them are highly expressed in young, developing tissues. To verify whether the newly identified proteins were indeed localized in the vacuole we constructed and expressed green fluorescence protein fusion proteins for five putative vacuolar membrane proteins exhibiting three to 11 transmembrane domains. Four of them, a putative organic cation transporter, a nodulin N21 family protein, a membrane protein of unknown function, and a senescence related membrane protein were localized in the vacuolar membrane, while a white-brown ATP-binding cassette transporter homolog was shown to reside in the plasma membrane. These results demonstrate that proteomic analysis of highly purified vacuoles from specific tissues allows the identification of new vacuolar proteins and provides an additional view of tonoplastic proteins.
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Affiliation(s)
- Ulrike G Schmidt
- University of Zürich, Institute of Plant Biology, CH-8008 Zurich, Switzerland
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87
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Sarry JE, Chen S, Collum RP, Liang S, Peng M, Lang A, Naumann B, Dzierszinski F, Yuan CX, Hippler M, Rea PA. Analysis of the vacuolar luminal proteome of Saccharomyces cerevisiae. FEBS J 2007; 274:4287-305. [PMID: 17651441 DOI: 10.1111/j.1742-4658.2007.05959.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Despite its large size and the numerous processes in which it is implicated, neither the identity nor the functions of the proteins targeted to the yeast vacuole have been defined comprehensively. In order to establish a methodological platform and protein inventory to address this shortfall, we refined techniques for the purification of 'proteomics-grade' intact vacuoles. As confirmed by retention of the preloaded fluorescent conjugate glutathione-bimane throughout the fractionation procedure, the resistance of soluble proteins that copurify with this fraction to digestion by exogenous extravacuolar proteinase K, and the results of flow cytometric, western and marker enzyme activity analyses, vacuoles prepared in this way retain most of their protein content and are of high purity and integrity. Using this material, 360 polypeptides species associated with the soluble fraction of the vacuolar isolates were resolved reproducibly by 2D gel electrophoresis. Of these, 260 were identified by peptide mass fingerprinting and peptide sequencing by MALDI-MS and liquid chromatography coupled to ion trap or quadrupole TOF tandem MS, respectively. The polypeptides identified in this way, many of which correspond to alternate size and charge states of the same parent translation product, can be assigned to 117 unique ORFs. Most of the proteins identified are canonical vacuolar proteases, glycosidases, phosphohydrolases, lipid-binding proteins or established vacuolar proteins of unknown function, or other proteases, glycosidases, lipid-binding proteins, regulatory proteins or proteins involved in intermediary metabolism, protein synthesis, folding or targeting, or the alleviation of oxidative stress. On the basis of the high purity of the vacuolar preparations, the electrophoretic properties of the proteins identified and the results of quantitative proteinase K protection measurements, many of the noncanonical vacuolar proteins identified are concluded to have entered this compartment for breakdown, processing and/or salvage purposes.
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Affiliation(s)
- Jean-Emmanuel Sarry
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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88
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Leshem Y, Seri L, Levine A. Induction of phosphatidylinositol 3-kinase-mediated endocytosis by salt stress leads to intracellular production of reactive oxygen species and salt tolerance. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 51:185-97. [PMID: 17521408 DOI: 10.1111/j.1365-313x.2007.03134.x] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Salt imposes immediate problems for plant cells, such as osmotic stress, impaired ion homeostasis and sodium toxicity, followed by a secondary oxidative stress caused by generation of reactive oxygen species (ROS). Here, we analyzed the production of ROS during salt stress. We show that salt stress triggered plasma membrane internalization, resulting in the production of ROS within endosomes. The intracellular ROS were produced by NADPH oxidase in response to the ionic but not the osmotic stress. Both endocytosis and ROS production were suppressed in phosphatidylinositol (PtdIns) 3-kinase (PI3K) mutants, PI3K being a key regulator of vesicle trafficking in animals and plants, and by wortmannin, which is a specific inhibitor of PI3K and PI4K. Endocytosis and the production of ROS were rescued by supplementation of seedlings with exogenous PtdIns 3-phosphate (PtdIns3P), less with PtdIns4P, but not with PtdIns(4,5)P(2). Surprisingly, despite reduced oxidative stress, the mutants and the wortmannin-treated plants exhibited a phenotype overly sensitive to salt, as also resulted from treatment with diphenyleneiodonium, a suicide inhibitor of NADPH oxidase, suggesting a positive role for ROS in salt tolerance. In summary, our results show that salt stress responses, such as increased plasma membrane endocytosis and the intracellular production of ROS, are coordinated by phospholipid-regulated signaling pathways, and suggest that ROS act in the signal transduction of the salt tolerance response.
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Affiliation(s)
- Yehoram Leshem
- Department of Plant Sciences, Institute of Life Sciences, The Hebrew University of Jerusalem, Givat-Ram, Jerusalem, Israel
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89
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Robert S, Zouhar J, Carter C, Raikhel N. Isolation of intact vacuoles from Arabidopsis rosette leaf-derived protoplasts. Nat Protoc 2007; 2:259-62. [PMID: 17406583 DOI: 10.1038/nprot.2007.26] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Vacuoles are very prominent compartments within plant cells, and understanding of their function relies on knowledge of their content. Here, we present a simple vacuole purification protocol that was successfully used for large-scale isolation of vacuoles, free of significant contamination from other endomembrane compartments. This method is based on osmotic and thermal disruption of mesophyl-derived Arabidopsis protoplasts, followed by a density gradient fractionation of the cellular content. The whole procedure, including protoplast isolation, takes approximately 6 h.
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Affiliation(s)
- Stéphanie Robert
- Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, Center for Plant Cell Biology, University of California, Riverside, California 92521, USA
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90
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Rentsch D, Schmidt S, Tegeder M. Transporters for uptake and allocation of organic nitrogen compounds in plants. FEBS Lett 2007; 581:2281-9. [PMID: 17466985 DOI: 10.1016/j.febslet.2007.04.013] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 04/10/2007] [Accepted: 04/11/2007] [Indexed: 10/23/2022]
Abstract
Nitrogen is an essential macronutrient for plant growth. Following uptake from the soil or assimilation within the plant, organic nitrogen compounds are transported between organelles, from cell to cell and over long distances in support of plant metabolism and development. These translocation processes require the function of integral membrane transporters. The review summarizes our current understanding of the molecular mechanisms of organic nitrogen transport processes, with a focus on amino acid, ureide and peptide transporters.
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Affiliation(s)
- Doris Rentsch
- University of Bern, Institute of Plant Sciences, Altenbergrain 21, 3011 Bern, Switzerland.
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91
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Bérczi A, Su D, Asard H. An Arabidopsis cytochrome b561 with trans-membrane ferrireductase capability. FEBS Lett 2007; 581:1505-8. [PMID: 17376442 DOI: 10.1016/j.febslet.2007.03.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 02/20/2007] [Accepted: 03/02/2007] [Indexed: 11/26/2022]
Abstract
Ascorbate-reducible cytochromes b561 (Cyts-b561) are a class of intrinsic trans-membrane proteins. Tonoplast Cyt-b561 (TCytb), one of the four Cyt-b561 isoforms in Arabidopsis was localized to the tonoplast. We demonstrate here that the optical spectra, EPR spectra and redox potentials of recombinant TCytb are similar to those of the well characterized bovine chromaffin granule Cyt-b561. We provide evidence for the reduction of ferric-chelates by the reduced TCytb. It is also shown that TCytb is capable of trans-membrane electron transport from intracellular ascorbate to extracellular ferric-chelates in yeast cells.
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Affiliation(s)
- Alajos Bérczi
- Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, PO Box 521, H-6701 Szeged, Hungary.
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92
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Ohnishi M, Mimura T, Tsujimura T, Mitsuhashi N, Washitani-Nemoto S, Maeshima M, Martinoia E. Inorganic phosphate uptake in intact vacuoles isolated from suspension-cultured cells of Catharanthus roseus (L.) G. Don under varying Pi status. PLANTA 2007; 225:711-8. [PMID: 16955272 DOI: 10.1007/s00425-006-0379-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2006] [Accepted: 08/07/2006] [Indexed: 05/11/2023]
Abstract
Inorganic phosphate (Pi) uptake across the vacuolar membrane of intact vacuoles isolated from Catharanthus roseus suspension-cultured cells was measured. Under low Pi status, Pi uptake into the vacuole was strongly activated compared to high Pi status. Since Pi uptake across the vacuolar membrane is correlated with H+ pumping, we examined the dependency of H+ pumping on plant Pi status. Both H+ pumping and the activities of the vacuolar H+-pumps, the V-type H+-ATPase and the H+-PPase were enhanced under low Pi status. Despite this increase in H+ pumping, Western blot analysis showed no distinct increase in the amount of proton pump proteins. Possible mechanisms for the activation of Pi uptake into the vacuole under low Pi status are discussed.
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Affiliation(s)
- Miwa Ohnishi
- Department of Biology, Faculty of Science, Kobe University, Rokkodai 1-1, Nada, Kobe 678-8501, Japan
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93
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94
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Becker B. Function and evolution of the vacuolar compartment in green algae and land plants (Viridiplantae). INTERNATIONAL REVIEW OF CYTOLOGY 2007; 264:1-24. [PMID: 17964920 DOI: 10.1016/s0074-7696(07)64001-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Plant vacuoles perform several different functions and are essential for the plant cell. The large central vacuoles of mature plant cells provide structural support, and they serve other functions, such as protein degradation and turnover, waste disposal, storage of metabolites, and cell growth. A unique feature of the plant vacuolar system is the presence of different types of vacuoles within the same cell. The current knowledge about the vacuolar compartments in plants and green algae is summarized and a hypothesis is presented to explain the origin of multiple types of vacuoles in plants.
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Affiliation(s)
- Burkhard Becker
- Botanical Institute, University of Cologne, 50931 Köln, Germany
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95
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Cho YH, Yoo SD, Sheen J. Regulatory functions of nuclear hexokinase1 complex in glucose signaling. Cell 2006; 127:579-89. [PMID: 17081979 DOI: 10.1016/j.cell.2006.09.028] [Citation(s) in RCA: 299] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 07/18/2006] [Accepted: 09/01/2006] [Indexed: 10/24/2022]
Abstract
Arabidopsis hexokinase1 (HXK1) is a glucose sensor that integrates nutrient and hormone signals to govern gene expression and plant growth in response to environmental cues. How the metabolic enzyme mediates glucose signaling remains a mystery. By coupling proteomic and binary-interaction screens, we discover two nuclear-specific HXK1 unconventional partners: the vacuolar H(+)-ATPase B1 (VHA-B1) and the 19S regulatory particle of proteasome subunit (RPT5B). Remarkably, vha-B1 and rpt5b mutants uniquely share a broad spectrum of glucose response defects with the HXK1 mutant gin2 (glucose-insensitive2). Genetic and chromatin immunoprecipitation analyses suggest that the nuclear HXK1 forms a glucose signaling complex core with VHA-B1 and RPT5B that directly modulates specific target gene transcription independent of glucose metabolism. The findings support a model in which conserved metabolic enzymes and proteins of well-established activities may perform previously unrecognized nuclear functions.
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Affiliation(s)
- Young-Hee Cho
- Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
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96
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Jaquinod M, Villiers F, Kieffer-Jaquinod S, Hugouvieux V, Bruley C, Garin J, Bourguignon J. A proteomics dissection of Arabidopsis thaliana vacuoles isolated from cell culture. Mol Cell Proteomics 2006; 6:394-412. [PMID: 17151019 PMCID: PMC2391258 DOI: 10.1074/mcp.m600250-mcp200] [Citation(s) in RCA: 248] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
To better understand the mechanisms governing cellular traffic, storage of various metabolites, and their ultimate degradation, Arabidopsis thaliana vacuole proteomes were established. To this aim, a procedure was developed to prepare highly purified vacuoles from protoplasts isolated from Arabidopsis cell cultures using Ficoll density gradients. Based on the specific activity of the vacuolar marker alpha-mannosidase, the enrichment factor of the vacuoles was estimated at approximately 42-fold with an average yield of 2.1%. Absence of significant contamination by other cellular compartments was validated by Western blot using antibodies raised against specific markers of chloroplasts, mitochondria, plasma membrane, and endoplasmic reticulum. Based on these results, vacuole preparations showed the necessary degree of purity for proteomics study. Therefore, a proteomics approach was developed to identify the protein components present in both the membrane and soluble fractions of the Arabidopsis cell vacuoles. This approach includes the following: (i) a mild oxidation step leading to the transformation of cysteine residues into cysteic acid and methionine to methionine sulfoxide, (ii) an in-solution proteolytic digestion of very hydrophobic proteins, and (iii) a prefractionation of proteins by short migration by SDS-PAGE followed by analysis by liquid chromatography coupled to tandem mass spectrometry. This procedure allowed the identification of more than 650 proteins, two-thirds of which copurify with the membrane hydrophobic fraction and one-third of which copurifies with the soluble fraction. Among the 416 proteins identified from the membrane fraction, 195 were considered integral membrane proteins based on the presence of one or more predicted transmembrane domains, and 110 transporters and related proteins were identified (91 putative transporters and 19 proteins related to the V-ATPase pump). With regard to function, about 20% of the proteins identified were known previously to be associated with vacuolar activities. The proteins identified are involved in ion and metabolite transport (26%), stress response (9%), signal transduction (7%), and metabolism (6%) or have been described to be involved in typical vacuolar activities, such as protein and sugar hydrolysis. The subcellular localization of several putative vacuolar proteins was confirmed by transient expression of green fluorescent protein fusion constructs.
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Affiliation(s)
- Michel Jaquinod
- Développement de la protéomique comme outil d'investigation fonctionelle et d'annotation des génomes
INSERM : ERM0201CEA17, rue des Martyrs 38054 Grenoble Cedex,FR
- * Correspondence should be adressed to: Michel Jaquinod
| | - Florent Villiers
- LPCV, Laboratoire de physiologie cellulaire végétale
CNRS : UMR5168INRA : UR1200CEA : DSV/IRTSVUniversité Joseph Fourier - Grenoble Ibat. C2
17 Rue des martyrs
38054 GRENOBLE CEDEX 9,FR
| | - Sylvie Kieffer-Jaquinod
- Développement de la protéomique comme outil d'investigation fonctionelle et d'annotation des génomes
INSERM : ERM0201CEA17, rue des Martyrs 38054 Grenoble Cedex,FR
| | - Véronique Hugouvieux
- LPCV, Laboratoire de physiologie cellulaire végétale
CNRS : UMR5168INRA : UR1200CEA : DSV/IRTSVUniversité Joseph Fourier - Grenoble Ibat. C2
17 Rue des martyrs
38054 GRENOBLE CEDEX 9,FR
| | - Christophe Bruley
- Développement de la protéomique comme outil d'investigation fonctionelle et d'annotation des génomes
INSERM : ERM0201CEA17, rue des Martyrs 38054 Grenoble Cedex,FR
| | - Jérôme Garin
- Développement de la protéomique comme outil d'investigation fonctionelle et d'annotation des génomes
INSERM : ERM0201CEA17, rue des Martyrs 38054 Grenoble Cedex,FR
| | - Jacques Bourguignon
- LPCV, Laboratoire de physiologie cellulaire végétale
CNRS : UMR5168INRA : UR1200CEA : DSV/IRTSVUniversité Joseph Fourier - Grenoble Ibat. C2
17 Rue des martyrs
38054 GRENOBLE CEDEX 9,FR
- * Correspondence should be adressed to: Jacques Bourguignon
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97
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Veljanovski V, Vanderbeld B, Knowles VL, Snedden WA, Plaxton WC. Biochemical and molecular characterization of AtPAP26, a vacuolar purple acid phosphatase up-regulated in phosphate-deprived Arabidopsis suspension cells and seedlings. PLANT PHYSIOLOGY 2006; 142:1282-93. [PMID: 16963519 PMCID: PMC1630754 DOI: 10.1104/pp.106.087171] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Accepted: 09/06/2006] [Indexed: 05/11/2023]
Abstract
A vacuolar acid phosphatase (APase) that accumulates during phosphate (Pi) starvation of Arabidopsis (Arabidopsis thaliana) suspension cells was purified to homogeneity. The final preparation is a purple APase (PAP), as it exhibited a pink color in solution (A(max) = 520 nm). It exists as a 100-kD homodimer composed of 55-kD glycosylated subunits that cross-reacted with an anti-(tomato intracellular PAP)-IgG. BLAST analysis of its 23-amino acid N-terminal sequence revealed that this PAP is encoded by At5g34850 (AtPAP26; one of 29 PAP genes in Arabidopsis) and that a 30-amino acid signal peptide is cleaved from the AtPAP26 preprotein during its translocation into the vacuole. AtPAP26 displays much stronger sequence similarity to orthologs from other plants than to other Arabidopsis PAPs. AtPAP26 exhibited optimal activity at pH 5.6 and broad substrate selectivity. The 5-fold increase in APase activity that occurred in Pi-deprived cells was paralleled by a similar increase in the amount of a 55-kD anti-(tomato PAP or AtPAP26)-IgG immunoreactive polypeptide and a >30-fold reduction in intracellular free Pi concentration. Semiquantitative reverse transcription-PCR indicated that Pi-sufficient, Pi-starved, and Pi-resupplied cells contain similar amounts of AtPAP26 transcripts. Thus, transcriptional controls appear to exert little influence on AtPAP26 levels, relative to translational and/or proteolytic controls. APase activity and AtPAP26 protein levels were also up-regulated in shoots and roots of Pi-deprived Arabidopsis seedlings. We hypothesize that AtPAP26 recycles Pi from intracellular P metabolites in Pi-starved Arabidopsis. As AtPAP26 also exhibited alkaline peroxidase activity, a potential additional role in the metabolism of reactive oxygen species is discussed.
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Affiliation(s)
- Vasko Veljanovski
- Department of Biology , Queen's University, Kingston, Ontario, Canada K7L 3N6
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98
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Hynek R, Svensson B, Jensen ON, Barkholt V, Finnie C. Enrichment and Identification of Integral Membrane Proteins from Barley Aleurone Layers by Reversed-Phase Chromatography, SDS-PAGE, and LC−MS/MS. J Proteome Res 2006; 5:3105-13. [PMID: 17081062 DOI: 10.1021/pr0602850] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The plasma membrane of the cereal aleurone layer is the site of perception of germination signals and release of enzymes to the starchy endosperm. Analysis of membrane proteins is challenging due to their hydrophobicity and low abundance; thus, little is known about the membrane proteins involved in seed germination. A membrane fraction highly enriched for the plasma membrane H+-ATPase was prepared from barley aleurone layers by aqueous two-phase partitioning. Because detergent and salt washes did not efficiently remove soluble proteins from the membrane preparations, an alternative procedure was developed, comprising batch reversed-phase chromatography with stepwise elution of hydrophobic proteins by 2-propanol. Proteins in the most hydrophobic fraction were separated by SDS-PAGE and identified by LC-MS/MS and barley EST sequence database search. The method was efficient for enrichment of integral membrane proteins with relatively low levels of soluble contaminating proteins. Forty-six proteins associated with barley aleurone plasma membranes were identified, including proteins with more than 10 transmembrane domains. Among the identified proteins were two new isoforms of the plasma membrane H+-ATPase, two proteins possibly involved in ion-channel regulation, and two proteins of unknown function. This represents the first analysis of membrane proteins involved in seed germination using a proteomics approach.
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Affiliation(s)
- Radovan Hynek
- Enzyme and Protein Chemistry Group, BioCentrum-DTU, Søltofts Plads, Building 224, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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99
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Abstract
With the avalanche of genomic information and improvements in analytical technology, proteomics is becoming increasingly important for the study of many different aspects of plant functions. Since proteins serve as important components of major signaling and biochemical pathways, studies at protein levels are essential to reveal molecular mechanisms underlying plant growth, development, and interactions with the environment. The plant proteome is highly complex and dynamic. Although great strides need to be taken towards the ultimate goal of characterizing all the proteins in a proteome, current technologies have provided immense opportunities for high-throughput proteomic studies that have gone beyond simple protein identification to analyzing various functional aspects, such as quantification, PTM, subcellular localization, and protein-protein interactions. In this review of plant proteomics, advances in protein fractionation, separation, and MS will be outlined. Focus will be on recent development in functional analysis of plant proteins, which paves the way towards the comprehensive integration with transcriptomics, metabolomics, and other large scale "-omics" into systems biology.
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Affiliation(s)
- Sixue Chen
- Department of Botany and Genetics Institute, University of Florida, Gainesville, FL 32611-8526, USA.
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100
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Voelker C, Schmidt D, Mueller-Roeber B, Czempinski K. Members of the Arabidopsis AtTPK/KCO family form homomeric vacuolar channels in planta. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 48:296-306. [PMID: 16984403 DOI: 10.1111/j.1365-313x.2006.02868.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The Arabidopsis thaliana K+ channel family of AtTPK/KCO proteins consists of six members including a 'single-pore' (Kir-type) and five 'tandem-pore' channels. AtTPK4 is currently the only ion channel of this family for which a function has been demonstrated in planta. The protein is located at the plasma membrane forming a voltage-independent K+ channel that is blocked by extracellular calcium ions. In contrast, AtTPK1 is a tonoplast-localized protein, that establishes a K+-selective, voltage-independent ion channel activated by cytosolic calcium when expressed in a heterologous system, i.e. yeast. Here, we provide evidence that other AtTPK/KCO channel subunits, i.e. AtTPK2, AtTPK3, AtTPK5 and AtKCO3, are also targeted to the vacuolar membrane, opening the possibility that they interact at the target membrane to form heteromeric ion channels. However, when testing the cellular expression patterns of AtTPK/KCO genes we observed distinct expression domains that overlap in only a few tissues of the Arabidopsis plant, making it unlikely that different channel subunits interact to form heteromeric channels. This conclusion was substantiated by in planta expression of combinations of selected tonoplast AtTPK/KCO proteins. Fluorescence resonance energy transfer assays indicate that protein interaction occurs between identical channel subunits (most efficiently between AtTPK1 or AtKCO3) but not between different channel subunits. The finding could be confirmed by bimolecular fluorescence complementation assays. We conclude that tonoplast-located AtTPK/KCO subunits form homomeric ion channels in vivo.
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Affiliation(s)
- Camilla Voelker
- Universität Potsdam, Institut für Biochemie und Biologie, Karl-Liebknecht-Str. 24-25, Haus 20, D-14476 Golm, Germany
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