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Ramos AC, Melo J, de Souza SB, Bertolazi AA, Silva RA, Rodrigues WP, Campostrini E, Olivares FL, Eutrópio FJ, Cruz C, Dias T. Inoculation with the endophytic bacterium Herbaspirillum seropedicae promotes growth, nutrient uptake and photosynthetic efficiency in rice. Planta 2020; 252:87. [PMID: 33057912 DOI: 10.1007/s00425-020-03496-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/09/2020] [Indexed: 06/11/2023]
Abstract
Higher vacuolar proton pump activity may increase plant energy and nutrient use efficiency and provide the nexus between plant inoculation with Herbaspirillum seropedicae and growth promotion. Global change and growing human population are exhausting arable land and resources, including water and fertilizers. We present inoculation with the endophytic plant-growth promoting bacterium (PGPB) Herbaspirillum seropedicae as a strategy for promoting growth, nutrient uptake and photosynthetic efficiency in rice (Oryza sativa L.). Because plant nutrient acquisition is coordinated with photosynthesis and the plant carbon status, we hypothesize that inoculation with H. seropedicae will stimulate proton (H+) pumps, increasing plant growth nutrient uptake and photosynthetic efficiency at low nutrient levels. Plants were inoculated and grown in pots with sterile soil for 90 days. Herbaspirillum seropedicae endophytic colonization was successful and, as hypothesized, inoculation (1) stimulated root vacuolar H+ pumps (vacuolar H+-ATPase and vacuolar H+-PPase), and (2) increased plant growth, nutrient contents and photosynthetic efficiency. The results showed that inoculation with the endophytic bacterium H. seropedicae can promote plant growth, nutrient uptake and photosynthetic efficiency, which will likely result in a more efficient use of resources (nutrients and water) and higher production of nutrient-rich food at reduced economic and environmental costs.
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Affiliation(s)
- Alessandro C Ramos
- Environmental Microbiology and Biotechnology Lab, Universidade Vila Velha (UVV), Vila Velha, ES, Brazil
| | - Juliana Melo
- Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Sávio B de Souza
- Environmental Microbiology and Biotechnology Lab, Universidade Vila Velha (UVV), Vila Velha, ES, Brazil
| | - Amanda A Bertolazi
- Environmental Microbiology and Biotechnology Lab, Universidade Vila Velha (UVV), Vila Velha, ES, Brazil
| | - Renderson A Silva
- Environmental Microbiology and Biotechnology Lab, Universidade Vila Velha (UVV), Vila Velha, ES, Brazil
| | - Weverton P Rodrigues
- Plant Physiology Lab, Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, RJ, Brazil
| | - Eliemar Campostrini
- Plant Physiology Lab, Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, RJ, Brazil
| | - Fábio L Olivares
- Cell Tissue and Biology Lab, Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, RJ, Brazil
| | - Frederico J Eutrópio
- Environmental Microbiology and Biotechnology Lab, Universidade Vila Velha (UVV), Vila Velha, ES, Brazil
| | - Cristina Cruz
- Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Teresa Dias
- Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal.
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Bertolazi AA, de Souza SB, Ruas KF, Campostrini E, de Rezende CE, Cruz C, Melo J, Colodete CM, Varma A, Ramos AC. Inoculation With Piriformospora indica Is More Efficient in Wild-Type Rice Than in Transgenic Rice Over-Expressing the Vacuolar H +-PPase. Front Microbiol 2019; 10:1087. [PMID: 31156595 PMCID: PMC6530341 DOI: 10.3389/fmicb.2019.01087] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/30/2019] [Indexed: 12/19/2022] Open
Abstract
Achieving food security in a context of environmental sustainability is one of the main challenges of the XXI century. Two competing strategies to achieve this goal are the use of genetically modified plants and the use of plant growth promoting microorganisms (PGPMs). However, few studies assess the response of genetically modified plants to PGPMs. The aim of this study was to compare the response of over-expressing the vacuolar H+-PPase (AVP) and wild-type rice types to the endophytic fungus; Piriformospora indica. Oryza sativa plants (WT and AVP) were inoculated with P. indica and 30 days later, morphological, ecophysiological and bioenergetic parameters, and nutrient content were assessed. AVP and WT plant heights were strongly influenced by inoculation with P. indica, which also promoted increases in fresh and dry matter of shoot in both genotypes. This may be related with the stimulatory effect of P. indica on ecophysiological parameters, especially photosynthetic rate, stomatal conductance, intrinsic water use efficiency and carboxylation efficiency. However, there were differences between the genotypes concerning the physiological mechanisms leading to biomass increment. In WT plants, inoculation with P. indica stimulated all H+ pumps. However, in inoculated AVP plants, H+-PPase was stimulated, but P- and V-ATPases were inhibited. Fungal inoculation enhanced nutrient uptake in both shoots and roots of WT and AVP plants, compared to uninoculated plants; but among inoculated genotypes, the nutrient uptake was lower in AVP than in WT plants. These results clearly demonstrate that the symbiosis between P. indica and AVP plants did not benefit those plants, which may be related to the inefficient colonization of this fungus on the transgenic plants, demonstrating an incompatibility of this symbiosis, which needs to be further studied.
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Affiliation(s)
- Amanda Azevedo Bertolazi
- Laboratory of Environmental Microbiology and Biotechnology, Universidade Vila Velha (UVV), Vila Velha, Brazil
| | - Sávio Bastos de Souza
- Laboratory of Plant Physiology, CCTA, Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, Brazil
| | - Katherine Fraga Ruas
- Laboratory of Plant Physiology, CCTA, Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, Brazil
| | - Eliemar Campostrini
- Laboratory of Plant Physiology, CCTA, Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, Brazil
| | - Carlos Eduardo de Rezende
- Laboratory of Environmental Sciences, CBB, Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, Brazil
| | - Cristina Cruz
- Centre for Ecology, Evolution and Environmental Changes (Ce3C), Faculty of Sciences, Universidade de Lisboa, Campo Grande, Portugal
| | - Juliana Melo
- Centre for Ecology, Evolution and Environmental Changes (Ce3C), Faculty of Sciences, Universidade de Lisboa, Campo Grande, Portugal
| | - Carlos Moacir Colodete
- Laboratory of Environmental Microbiology and Biotechnology, Universidade Vila Velha (UVV), Vila Velha, Brazil
| | - Ajit Varma
- Amity Institute of Microbial Technology, Amity University, Noida, India
| | - Alessandro Coutinho Ramos
- Laboratory of Environmental Microbiology and Biotechnology, Universidade Vila Velha (UVV), Vila Velha, Brazil
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Passamani LZ, Bertolazi AA, Ramos AC, Santa-Catarina C, Thelen JJ, Silveira V. Embryogenic Competence Acquisition in Sugar Cane Callus Is Associated with Differential H+-Pump Abundance and Activity. J Proteome Res 2018; 17:2767-2779. [DOI: 10.1021/acs.jproteome.8b00213] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Lucas Z. Passamani
- Laboratório de Biotecnologia, Centro de Biociências e Biotecnologia (CBB), Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Avenue Alberto Lamego 2000, Campos dos Goytacazes, Rio de Janeiro 28013-602, Brazil
- Unidade de Biologia Integrativa, Setor de Genômica e Proteômica, UENF, Avenue Alberto Lamego 2000, Campos dos Goytacazes, Rio de Janeiro 28013-602, Brazil
| | - Amanda A. Bertolazi
- Laboratório de Fisiologia e Bioquímica de Microrganismos, CBB-UENF, Avenue Alberto Lamego 2000, Campos dos Goytacazes, Rio de Janeiro 28013-602, Brazil
| | - Alessandro C. Ramos
- Laboratório de Fisiologia e Bioquímica de Microrganismos, CBB-UENF, Avenue Alberto Lamego 2000, Campos dos Goytacazes, Rio de Janeiro 28013-602, Brazil
| | - Claudete Santa-Catarina
- Laboratório de Biologia Celular e Tecidual, CBB-UENF, Avenue Alberto Lamego 2000, Campos dos Goytacazes, Rio de Janeiro 28013-602, Brazil
| | | | - Vanildo Silveira
- Laboratório de Biotecnologia, Centro de Biociências e Biotecnologia (CBB), Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Avenue Alberto Lamego 2000, Campos dos Goytacazes, Rio de Janeiro 28013-602, Brazil
- Unidade de Biologia Integrativa, Setor de Genômica e Proteômica, UENF, Avenue Alberto Lamego 2000, Campos dos Goytacazes, Rio de Janeiro 28013-602, Brazil
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Zhan X, Yi X, Yue L, Fan X, Xu G, Xing B. Cytoplasmic pH-Stat during Phenanthrene Uptake by Wheat Roots: A Mechanistic Consideration. Environ Sci Technol 2015; 49:6037-6044. [PMID: 25923043 DOI: 10.1021/acs.est.5b00697] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Dietary intake of plant-based foods is a major contribution to the total exposure of polycyclic aromatic hydrocarbons (PAHs). However, the mechanisms underlying PAH uptake by roots remain poorly understood. This is the first study, to our knowledge, to reveal cytoplasmic pH change and regulation in response to PAH uptake by wheat roots. An initial drop of cytoplasmic pH, which is concentration-dependent upon exposure to phenanthrene (a model PAH), was followed by a slow recovery, indicating the operation of a powerful cytoplasmic pH regulating system. Intracellular buffers are prevalent and act in the first few minutes of acidification. Phenanthrene activates plasmalemma and tonoplast H(+) pump. Cytolasmic acidification is also accompanied by vacuolar acidification. In addition, phenanthrene decreases the activity of phosphoenolpyruvate carboxylase and malate concentration. Moreover, phenanthrene stimulates nitrate reductase. Therefore, it is concluded that phenanthrene uptake induces cytoplasmic acidification, and cytoplasmic pH recovery is achieved via physicochemical buffering, proton transport outside cytoplasm into apoplast and vacuole, and malate decarboxylation along with nitrate reduction. Our results provide a novel insight into PAH uptake by wheat roots, which is relevant to strategies for reducing PAH accumulation in wheat for food safety and improving phytoremediation of PAH-contaminated soils or water by agronomic practices.
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Affiliation(s)
- Xinhua Zhan
- †College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Xiu Yi
- †College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Le Yue
- †College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
- ‡Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Xiaorong Fan
- †College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Guohua Xu
- †College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Baoshan Xing
- ‡Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
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Venancio JB, Catunda MG, Ogliari J, Rima JAH, Okorokova-Facanha AL, Okorokov LA, Facanha AR. A vacuolar H(+)-pyrophosphatase differential activation and energy coupling integrate the responses of weeds and crops to drought stress. Biochim Biophys Acta Gen Subj 2013; 1840:1987-92. [PMID: 24365406 DOI: 10.1016/j.bbagen.2013.12.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 12/04/2013] [Accepted: 12/15/2013] [Indexed: 11/24/2022]
Abstract
BACKGROUND Cyperus rotundus L. is a C4 weed of large vegetative and reproductive vigor endowed with competitive advantages over most crop species mainly under adverse environmental conditions. Vacuole functions are critical for the mechanisms of drought resistance, and here the modulation of the primary system of vacuolar ion transport is investigated during a transient water stress imposed to this weed and to C4 crop species (Zea mays L.). METHODS The vacuolar H(+) pumps, the H(+)-ATPase and H(+)-PPiase, expression, activities and the energy coupling were spectrophotometrically investigated as key elements in the differential drought-resistance mechanisms developed by weeds and crops. RESULTS In C. rotundus tonoplasts, ATP hydrolysis was more sensitive to drought than its coupled H(+) transport, which was in turn at least 3-folds faster than that mediated by the H(+)-PPiase. Its PPi hydrolysis was only slightly affected by severe water deficit, contrasting with the disruption induced in the PPi-dependent H(+)-gradient. This effect was antagonized by plant rehydration as the H(+)-PPiase activity was highly stimulated, reassuming a coupled PPi-driven H(+) pumping. Maize tonoplasts exhibited 2-4 times lower hydrolytic activities than that of C. rotundus, but were able to overactivate specifically PPi-dependent H(+) pumping in response to stress relief, resulting in an enhanced H(+)-pumps coupling efficiency. CONCLUSION These results together with immunoanalysis revealed profiles consistent with pre- and post-translational changes occurring on the tonoplast H(+)-pumps, which differ between weeds and crops upon water deficit. GENERAL SIGNIFICANCE The evidences highlight an unusual modulation of the H(+)-PPiase energy coupling as a key biochemical change related to environmental stresses adaptive capacity of plants.
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Affiliation(s)
- Josimara Barcelos Venancio
- Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil; Núcleo de Desenvolvimento de Insumos Biológicos para Agricultura (NUDIBA), Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil
| | | | - Juarez Ogliari
- Instituto Federal Fluminense, Bom Jesus do Itabapoana, RJ, Brazil
| | - Janaína Aparecida Hottz Rima
- Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil; Núcleo de Desenvolvimento de Insumos Biológicos para Agricultura (NUDIBA), Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil
| | - Anna Lvovna Okorokova-Facanha
- Laboratório de Fisiologia e Bioquímica de Microorganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil
| | - Lev Alexandrovitich Okorokov
- Laboratório de Fisiologia e Bioquímica de Microorganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil
| | - Arnoldo Rocha Facanha
- Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil; Núcleo de Desenvolvimento de Insumos Biológicos para Agricultura (NUDIBA), Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil.
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Dutra NT, Silveira V, de Azevedo IG, Gomes-Neto LR, Façanha AR, Steiner N, Guerra MP, Floh EIS, Santa-Catarina C. Polyamines affect the cellular growth and structure of pro-embryogenic masses in Araucaria angustifolia embryogenic cultures through the modulation of proton pump activities and endogenous levels of polyamines. Physiol Plant 2013; 148:121-132. [PMID: 22998677 DOI: 10.1111/j.1399-3054.2012.01695.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/05/2012] [Accepted: 07/05/2012] [Indexed: 06/01/2023]
Abstract
Polyamines (PAs) are abundant polycationic compounds involved in many physiological processes in plants, including somatic embryogenesis. This study investigates the role of PAs on cellular growth and structure of pro-embryogenic masses (PEMs), endogenous PA and proton pump activities in embryogenic suspension cultures of Araucaria angustifolia. The embryogenic suspension cultures were incubated with putrescine (Put), spermidine (Spd), spermine (Spm) and the inhibitor methylglyoxal-bis(guanylhydrazone) (MGBG), respectively (1 mM). After 24 h and 21 days, the cellular growth and structure of PEMs, endogenous PA contents and proton pump activities were analyzed. The addition of Spm reduced the cellular growth and promoted the development of PEMs in embryogenic cultures, which could be associated with a reduction in the activities of proton pumps, such as H(+) -ATPase P- and V-types and H(+) -PPases, and alterations in the endogenous PA contents. Spm significantly affected the physiology of the A. angustifolia somatic embryogenesis suspension, as it potentially affects cellular growth and structure of PEMs through the modulation of proton pump activities. This work demonstrates the involvement of exogenous PAs in the modulation of cellular growth and structure of PEMs, endogenous PA levels and proton pump activities during somatic embryogenesis. To our knowledge, this study is the first to report a relationship between PAs and proton pump activities in these processes. The results obtained in this study offer new perspectives for studies addressing the role of PAs and proton pump on somatic embryogenesis in this species.
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Affiliation(s)
- Nathalia Torres Dutra
- Cell Biology and Tissue Laboratory (LBCT), Bioscience and Biotechnology Center (CBB), State University of Norte Fluminense "Darcy Ribeiro" (UENF), Campos dos Goytacazes, RJ, 28013-602, Brazil
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Zhang M, Fang Y, Liang Z, Huang L. Enhanced expression of vacuolar H+-ATPase subunit E in the roots is associated with the adaptation of Broussonetia papyrifera to salt stress. PLoS One 2012; 7:e48183. [PMID: 23133565 DOI: 10.1371/journal.pone.0048183] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Accepted: 09/21/2012] [Indexed: 02/07/2023] Open
Abstract
Vacuolar H+-ATPase (V-H+-ATPase) may play a pivotal role in maintenance of ion homeostasis inside plant cells. In the present study, the expression of V-H+-ATPase genes was analyzed in the roots and leaves of a woody plant, Broussonetia papyrifera, which was stressed with 50, 100 and 150 mM NaCl. Moreover, the expression and distribution of the subunit E protein were investigated by Western blot and immunocytochemistry. These showed that treatment of B. papyrifera with NaCl distinctly changed the hydrolytic activity of V-H+-ATPase in the roots and leaves. Salinity induced a dramatic increase in V-H+-ATPase hydrolytic activity in the roots. However, only slight changes in V-H+-ATPase hydrolytic activity were observed in the leaves. In contrast, increased H+ pumping activity of V-H+-ATPase was observed in both the roots and leaves. In addition, NaCl treatment led to an increase in H+-pyrophosphatase (V-H+-PPase) activity in the roots. Moreover, NaCl treatment triggered the enhancement of mRNA levels for subunits A, E and c of V-H+-ATPase in the roots, whereas only subunit c mRNA was observed to increase in the leaves. By Western blot and immunocytological analysis, subunit E was shown to be augmented in response to salinity stress in the roots. These findings provide evidence that under salt stress, increased V-H+-ATPase activity in the roots was positively correlated with higher transcript and protein levels of V-H+-ATPase subunit E. Altogether, our results suggest an essential role for V-H+-ATPase subunit E in the response of plants to salinity stress.
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Amoroso S, Clarke RJ, Larkum A, Quinnell R. Electrogenic plasma membrane H+-ATPase activity using voltage sensitive dyes. J Bioenerg Biomembr 2010; 42:387-93. [PMID: 20734224 DOI: 10.1007/s10863-010-9306-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 07/28/2010] [Indexed: 10/19/2022]
Abstract
Fast responding voltage sensitive dyes, RH421 and di-4-ASPBS, were used to study the electrogenic properties of plant plasma membrane proton pumps on sealed plasma membrane vesicles extracted by two-phase partitioning from Beta vulgaris and Avena sativa cv Swan root material. Fluorescence spectroscopy in the presence of the dye RH421 (10.8 nM) was sufficiently sensitive to detect electrogenic activity of the extracted plant vesicles. The dye detection system could detect inhibition of electrogenic activity of vesicles by vanadate (75 μM) and stimulation by nigericin (0.5 μM). The newly developed dye di-4-ASPBS was less sensitive to detecting the electrogenic proton pump activity. This study represents an important innovation in plant biophysics as this class of fast responding voltage sensitive dyes have never to our knowledge been used to study electrogenic proton pump activity derived from plant membranes and represents a novel approach for carrying out such studies.
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Qiu QS, Guo Y, Quintero FJ, Pardo JM, Schumaker KS, Zhu JK. Regulation of Vacuolar Na+/H+ Exchange in Arabidopsis thaliana by the Salt-Overly-Sensitive (SOS) Pathway. J Biol Chem 2004; 279:207-15. [PMID: 14570921 DOI: 10.1074/jbc.m307982200] [Citation(s) in RCA: 228] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
For plants growing in highly saline environments, accumulation of sodium in the cell cytoplasm leads to disruption of metabolic processes and reduced growth. Maintaining low levels of cytoplasmic sodium requires the coordinate regulation of transport proteins on numerous cellular membranes. Our previous studies have linked components of the Salt-Overly-Sensitive pathway (SOS1-3) to salt tolerance in Arabidopsis thaliana and demonstrated that the activity of the plasma membrane Na+/H+ exchanger (SOS1) is regulated by SOS2 (a protein kinase) and SOS3 (a calcium-binding protein). Current studies were undertaken to determine if the Na+/H+ exchanger in the vacuolar membrane (tonoplast) of Arabidopsis is also a target for the SOS regulatory pathway. Characterization of tonoplast Na+/H+ exchange demonstrated that it represents activity originating from the AtNHX proteins since it could be inhibited by 5-(N-methyl-N-isobutyl)amiloride and by anti-NHX1 antibodies. Transport activity was selective for sodium (apparent Km=31 mm) and electroneutral (one sodium ion for each proton). When compared with tonoplast Na+/H+-exchange activity in wild type, activity was significantly higher, greatly reduced, and unchanged in sos1, sos2, and sos3, respectively. Activated SOS2 protein added in vitro increased tonoplast Na+/H+-exchange activity in vesicles isolated from sos2 but did not have any effect on activity in vesicles isolated from wild type, sos1, or sos3. These results demonstrate that (i) the tonoplast Na+/H+ exchanger in Arabidopsis is a target of the SOS regulatory pathway, (ii) there are branches to the SOS pathway, and (iii) there may be coordinate regulation of the exchangers in the tonoplast and plasma membrane.
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Affiliation(s)
- Quan-Sheng Qiu
- Department of Plant Sciences, University of Arizona, Tucson, Arizona 85721, USA
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Abstract
In plants, Na+/H+ exchangers in the plasma membrane are critical for growth in high levels of salt, removing toxic Na+ from the cytoplasm by transport out of the cell. The molecular identity of a plasma membrane Na+/H+ exchanger in Arabidopsis (SOS1) has recently been determined. In this study, immunological analysis provided evidence that SOS1 localizes to the plasma membrane of leaves and roots. To characterize the transport activity of this protein, purified plasma membrane vesicles were isolated from leaves of Arabidopsis. Na+/H+ exchange activity, monitored as the ability of Na to dissipate an established pH gradient, was absent in plants grown without salt. However, exchange activity was induced when plants were grown in 250 mm NaCl and increased with prolonged salt exposure up to 8 d. H+-coupled exchange was specific for Na, because chloride salts of other monovalent cations did not dissipate the pH gradient. Na+/H+ exchange activity was dependent on Na (substrate) concentration, and kinetic analysis indicated that the affinity (apparent Km) of the transporter for Na+ is 22.8 mm. Data from two experimental approaches supports electroneutral exchange (one Na+ exchanged for one proton): (a) no change in membrane potential was measured during the exchange reaction, and (b) Na+/H+ exchange was unaffected by the presence or absence of a membrane potential. Results from this research provide a framework for future studies into the regulation of the plant plasma membrane Na+/H+ exchanger and its relative contribution to the maintenance of cellular Na+ homeostasis during plant growth in salt.
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Affiliation(s)
- Quan-Sheng Qiu
- Department of Plant Sciences, University of Arizona, Tucson 85721, USA
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Rocha Facanha A, de Meis L. Reversibility of H+-ATPase and H+-pyrophosphatase in tonoplast vesicles from maize coleoptiles and seeds. Plant Physiol 1998; 116:1487-95. [PMID: 9536067 DOI: 10.1104/pp.116.4.1487] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/1997] [Accepted: 12/04/1997] [Indexed: 05/17/2023]
Abstract
Tonoplast-enriched vesicles isolated from maize (Zea mays L.) coleoptiles and seeds synthesize ATP from ADP and inorganic phosphate (Pi) and inorganic pyrophosphate from Pi. The synthesis is consistent with reversal of the catalytic cycle of the H+-ATPase and H+-pyrophosphatase (PPase) vacuolar membrane-bound enzymes. This was monitored by measuring the exchange reaction that leads to 32Pi incorporation into ATP or inorganic pyrophosphate. The reversal reactions of these enzymes were dependent on the proton gradient formed across the vesicle membrane and were susceptible to the uncoupler carbonyl cyanide p(trifluoromethoxy)-phenylhydrazone and the detergent Triton X-100. Comparison of the two H+ pumps showed that the H+-ATPase was more active than H+-PPase in coleoptile tonoplast vesicles, whereas in seed vesicles H+-PPase activity was clearly dominant. These findings may reflect the physiological significance of these enzymes in different tissues at different stages of development and/or differentiation.
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Abstract
The role of the plant plasma membrane H+-ATPase in K+ uptake was examined using red beet (Beta vulgaris L.) plasma membrane vesicles and a partially purified preparation of the red beet plasma membrane H+-ATPase reconstituted in proteoliposomes and planar bilayers. For plasma membrane vesicles, ATP-dependent K+ efflux was only partially inhibited by 100 [mu]M vanadate or 10 [mu]M carbonyl cyanide-p-trifluoromethoxyphenylhydrazone. However, full inhibition of ATP-dependent K+ efflux by these reagents occurred when the red beet plasma membrane H+-ATPase was partially purified and reconstituted in proteoliposomes. When reconstituted in a planar bilayer membrane, the current/voltage relationship for the plasma membrane H+-ATPase showed little effect of K+ gradients imposed across the bilayer membrane. When taken together, the results of this study demonstrate that the plant plasma membrane H+-ATPase does not mediate direct K+ transport chemically linked to ATP hydrolysis. Rather, this enzyme provides a driving force for cellular K+ uptake by secondary mechanisms, such as K+ channels or H+/K+ symporters. Although the presence of a small, protonophore-insensitive component of ATP-dependent K+ transport in a plasma membrane fraction might be mediated by an ATP-activated K+ channel, the possibility of direct K+ transport by other ATPases (i.e. K+-ATPases) associated with either the plasma membrane or other cellular membranes cannot be ruled out.
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Affiliation(s)
- D. P. Briskin
- Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801
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Abstract
Plasma membrane H+-ATPase was studied in maize (Zea mays L.) roots induced for NO3- uptake. Membrane vesicles were isolated by means of Suc density gradient from roots exposed for 24 h either to 1.5 mM NO3- or 1.5 mM SO4-. The two populations of vesicles had similar composition as shown by diagnostic inhibitors of membrane-associated ATPases. However, both ATP-dependent intravesicular H+ accumulation and ATP hydrolysis were considerably enhanced (60-100%) in vesicles isolated from NO3--induced roots. Km for Mg:ATP and pH dependency were not influenced by NO3- treatment of the roots. ATP hydrolysis in plasma membrane vesicles for both control and NO3--induced roots was not affected by 10 to 150 mM NO3- or Cl-. On the other hand, kinetics of NO3-- or Cl--stimulated ATP-dependent intravesicular H+ accumulation were modified in plasma membrane vesicles isolated from NO3-- induced roots. Immunoassays carried out with polyclonal antibodies against plasma membrane H+-ATPase revealed an increased steady-state level of the enzyme in plasma membrane vesicles isolated from NO3--induced roots. Results are consistent with the idea of an involvement of plasma membrane H+-ATPase in the overall response of roots to NO3-.
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Affiliation(s)
- S. Santi
- Dipartimento di Produzione Vegetale e Tecnologie Agrarie, University of Udine, Via Delle Scienze 208, I-33100 Udine, Italy
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14
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Briskin DP, Basu S, Assmann SM. Characterization of the Red Beet Plasma Membrane H+-ATPase Reconstituted in a Planar Bilayer System. Plant Physiol 1995; 108:393-398. [PMID: 12228483 PMCID: PMC157346 DOI: 10.1104/pp.108.1.393] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The transport activity of the red beet (Beta vulgaris L.) plasma membrane H+-ATPase was examined following reconstitution into a planar bilayer membrane. Fusion of partially purified plasma membrane H+-ATPase with the bilayer membrane was accomplished by perfusion of proteoliposomes against the bilayer under hypoosmotic conditions. Following incorporation into the bilayer, an ATP-dependent current was measured that demonstrated properties consistent with those of the plasma membrane H+-ATPase. Current production was substrate specific for ATP, inhibited by orthovanadate, and insensitive to 200 nM erythrosin B but inhibited by 100 [mu]M erythrosin B. When current production was measured as a function of Mg:ATP concentration, a simple Michaelis-Menten relationship was observed and a Km of 0.62 mM was estimated. Current-voltage analysis of ATP-dependent current in the presence of 0.5 mM ATP, 20 mM ADP, 40 mM orthophosphate, and an opposing 2.5-unit [delta]pH revealed a reversal potential of about -149 mV. Based on the free energy available from ATP hydrolysis, this reversal potential is consistent with an H+/ATP stoichiometry of 1. This study demonstrates the usefulness of a planar bilayer system for investigation of energy coupling to H+ transport by the plasma membrane H+-ATPase.
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Affiliation(s)
- D. P. Briskin
- Department of Agronomy, University of Illinois, Urbana, Illinois 61801 (D.P.B., S.B.)
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15
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Ros R, Romieu C, Gibrat R, Grignon C. The plant inorganic pyrophosphatase does not transport K+ in vacuole membrane vesicles multilabeled with fluorescent probes for H+, K+, and membrane potential. J Biol Chem 1995; 270:4368-74. [PMID: 7876200 DOI: 10.1074/jbc.270.9.4368] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
It has been claimed that the inorganic pyrophosphatase (PPase) of the plant vacuolar membrane transports K+ in addition to H+ in intact vacuoles (Davies, J. M., Poole, R. J., Rea, P. A., and Sanders, D. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 11701-11705). Since this was not confirmed using the purified and reconstituted PPase consisting of a 75-kDa polypeptide (Sato, M.H., Kasahara, M., Ishii, N., Homareda, H., Matsui, H., and Yoshida, M. (1994) J. Biol. Chem. 269, 6725-6728), these authors proposed that K+ transport by the PPase is dependent on its association with other membrane components lost during purification. We have examined the hypothesis of K+ translocation by the PPase using native vacuolar membrane vesicles from Vitis vinifera suspension cells, multilabeled with fluorescent probes for K+, H+, and membrane potential. This material contained a high proportion of right-side-out, tightly sealed vesicles, exhibiting high PPase activity which was strongly stimulated by uncouplers and K+. Proton pumping occurred in response to pyrophosphate addition in the absence of K+. No K+ incorporation into the vesicles could be observed after PPase energization in the presence of K+, although H+ transport was highly stimulated. The hydrolytic activity was stimulated by a protonophore and by a H+/K+ exchanger but not by the K+ ionophore valinomycin. No evidence could be obtained supporting the operation of an endogenous K+/H+ exchanger capable to dissipate the putative active K+ flux generated by the PPase. We conclude that PPase in native vacuolar membrane vesicles does not transport K+.
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Affiliation(s)
- R Ros
- Departament de Biologia Vegetal, Facultat de Ciències Biològiques, Universitat de València, Burjassot (València), Spain
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16
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Petrov VV, Smirnova VV, Okorokov LA. Mercaptoethanol and dithiothreitol decrease the difference of electrochemical proton potentials across the yeast plasma and vacuolar membranes and activate their H(+)-ATPases. Yeast 1992; 8:589-98. [PMID: 1441739 DOI: 10.1002/yea.320080803] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Mercaptoethanol and dithiothreitol (DTT) inhibited the acidification of external medium by Saccharomyces carlsbergensis cells and protoplasts during glucose oxidation. The inhibition was also observed when cells were incubated with mercaptoethanol or when mercaptoethanol and DTT were used to prepare protoplasts. Experiments with S. carlsbergensis plasma membrane vesicles and vacuoles showed these thiol reagents to inhibit ATP-dependent generation of delta pH and Em across plasma membrane vesicles and vacuoles but to activate their H(+)-ATPases. Mercaptoethanol and DTT are suggested to de-energize plasmalemma as well as tonoplast by increasing their H(+)-permeability and to disturb the cell ion homeostasis.
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Affiliation(s)
- V V Petrov
- Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region
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17
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Briskin DP. The plasma membrane H+-ATPase of higher plant cells: biochemistry and transport function. Biochimica et Biophysica Acta (BBA) - Bioenergetics 1990; 1019:95-109. [DOI: 10.1016/0005-2728(90)90129-r] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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18
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Suhayda CG, Giannini JL, Briskin DP, Shannon MC. Electrostatic Changes in Lycopersicon esculentum Root Plasma Membrane Resulting from Salt Stress. Plant Physiol 1990; 93:471-8. [PMID: 16667490 PMCID: PMC1062536 DOI: 10.1104/pp.93.2.471] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Salinity-induced alterations in tomato (Lypersicon esculentum Mill. cv Heinz 1350) root plasma membrane properties were studied and characterized using a membrane vesicle system. Equivalent rates of MgATP-dependent H(+)-transport activity were measured by quinacrine fluorescence (DeltapH) in plasma membrane vesicles isolated from control or salt-stressed (75 millimolar salt) tomato roots. However, when bis-[3-phenyl-5-oxoisoxazol-4-yl] pentamethine was used to measure MgATP-dependent membrane potential (DeltaPsi) formation, salt-stressed vesicles displayed a 50% greater initial quench rate and a 30% greater steady state quench than control vesicles. This differential probe response suggested a difference in surface properties between control and salt-stressed membranes. Fluorescence titration of vesicles with the surface potential probe, 8-anilino-1-napthalenesulphonic acid (ANS) provided dissociation constants (K(d)) of 120 and 76 micromolar for dye binding to control and salt-stressed vesicles, respectively. Membrane surface potentials (Psi(o)) of-26.0 and -13.7 millivolts were calculated for control and salt-stressed membrane vesicles from the measured K(d) values and the calculated intrinsic affinity constant, K(i). The concentration of cations and anions at the surface of control and salt-stressed membranes was estimated using Psi(o) values and the Boltzmann equation. The observed difference in membrane surface electrostatic properties was consistent with the measured differences in K(+)-stimulated kinetics of ATPase activity between control and salt-stressed vesicles and by the differential ability of Cl(-) ions to stimulate H(+)-transport activity. Salinity-induced changes in plasma membrane electrostatic properties may influence ion transport across the plasma membrane.
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Affiliation(s)
- C G Suhayda
- Department of Crop Science and Plant Ecology, University of Saskatchewan, Saskatoon, Saskatchewan S7N OWO Canada
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19
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White PJ, Smith JA. Proton and anion transport at the tonoplast in crassulacean-acid-metabolism plants: specificity of the malate-influx system in Kalanchoë daigremontiana. Planta 1989; 179:265-274. [PMID: 24201527 DOI: 10.1007/bf00393698] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/1989] [Accepted: 05/25/1989] [Indexed: 06/02/2023]
Abstract
Tonoplast vesicles were prepared from leaf mesophyll homogenates of the crassulacean-acid-metabolism plant Kalanchoë daigremontiana Hamet et Perrier de la Bâthie to study the effects of anions on ATP- and inorganic-pyrophosphate (PPi)-dependent H(+) transport. In the presence of gramicidin, substrate hydrolysis by the tonoplast ATPase was characteristically stimulated by chloride and inhibited by nitrate, but was unaffected by malate and a wide range of other organic-acid anions; the PPiase was anion-insensitive. Malate was more effective than chloride both in stimulating ATP- and PPi-dependent vesicle acidification (measured as quinacrine-fluorescence quenching) and in dissipating a pre-existing inside-positive membrane potential (measured as oxonol-V-fluorescence quenching), indicating that malate was more readily transported across the tonoplast. Certain other four-carbon dicarboxylates also supported high rates of vesicle acidification, their order of effectiveness being fumarate ≫ malate ∼-succinate > oxalacetate ∼- tartrate; the five-carbon dicarboxylates 2-oxoglutarate and glutarate were also transported, although at lower rates. Experiments with non-naturally occurring anions indicated that the malate transporter was not stereospecific, but that it required the trans-carboxyl configuration for transport. Shorter-chain or longer-chain dicarboxylates were not transported, and neither were monocarboxylates, the amino-acid anions aspartate and glutamate, nor the tricarboxylate isocitrate. The non-permeant anions maleate and tartronate appeared to be competitive inhibitors of malate transport but did not affect chloride transport, indicating that malate and chloride influx at the tonoplast might be mediated by separate transporters.
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Affiliation(s)
- P J White
- Department of Botany, University of Edinburgh, The King's Buildings, Mayfield Road, EH9 3JH, Edinburgh, UK
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20
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Brauer D, Tu SL, Hsu AF, Thomas CE. Kinetic analysis of proton transport by the vanadate-sensitive ATPase from maize root microsomes. Plant Physiol 1989; 89:464-71. [PMID: 16666566 PMCID: PMC1055864 DOI: 10.1104/pp.89.2.464] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Proton transport by the nitrate-insensitive, vanadate-sensitive ATPase in Kl-washed microsomes and reconstituted vesicles from maize (Zea mays L.) roots was followed by changes in acridine orange absorbance in the presence of either KNO(3) or KCl. Data from such studies obeyed a kinetic model in which net proton transport by the pump is the difference between the rate of proton transport by the action of the ATPase and the leak of protons from the vesicles in the direction opposite from the pump. After establishing the steady state proton gradient, the rate of return of transported protons was found to obey first-order kinetics when the activity of the ATPase was completely and rapidly stopped. The rate of return of these protons varied with the quencher used. When the substrate Mg:ATP was depleted by the addition of either EDTA or hexokinase, the rate at which the proton gradient collapsed was faster than when vanadate was used as the quencher. These trends were independent of the anion accompanying the K and the transport assay used.
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Affiliation(s)
- D Brauer
- Plant and Soil Biophysics Research Unit, Eastern Regional Research Center, Philadelphia, Pennsylvania 19118
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21
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Abstract
A microscale method for the isolation of selectively sealed microsomal membrane fractions from plant tissue is presented. The method is based on differential centrifugation in a table top microcentrifuge to accommodate small sample size (10-25 g tissue) and the addition of KI or KCl in the homogenization medium for isolating selectively sealed plasma membrane or tonoplast vesicles. This microscale procedure was found to be useful in isolating membranes from red beet (Beta vulgaris) storage tissue, sugar beet (Beta vulgaris) storage tissue, corn (Zea mays) roots, and soybean (Glycine max) roots. This paper also describes the ability to further purify an enriched red beet plasma membrane fraction on a discontinuous sucrose density gradient, in a microcentrifuge, that is highly competent in ATP-dependent H+-transport. The speed and wide applicability of this procedure make it ideal when a large number of samples need to be processed.
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Affiliation(s)
- J L Giannini
- Department of Agronomy, University of Illinois, Urbana 61801
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Giannini JL, Holt JS, Briskin DP. Isolation of sealed plasma membrane vesicles from Phytophthora megasperma f. sp. glycinea: II. Partial characterization of Ca2+ transport and glyceollin effects. Arch Biochem Biophys 1988; 266:644-9. [PMID: 3142364 DOI: 10.1016/0003-9861(88)90298-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Calcium uptake was examined in sealed plasma membrane vesicles isolated from the plant pathogenic fungus, Phytophthora megasperma f. sp. glycinea. Calcium uptake was ATP-dependent and by the addition of various ionophores in the presence of ATP, it was shown that Ca2+ transport was mediated by a nH+/Ca2+ antiport. Further evidence for this antiport mechanism included Ca2+ uptake driven by an imposed pH gradient and the observation that calcium could dissipate a steady-state pH gradient across the vesicle membrane. Transport mediated by the nH+/Ca2+ antiport was optimal at pH 7.0, and demonstrated saturation kinetics for Ca2+ with a Km of about 7 microM. Glyceollin, a soybean phytoalexin, was found to inhibit Ca2+ transport consistent with its ability to increase H+ conductance. In the presence of glyceollin, calcium leakage from Phytophthora membrane vesicles also increased. This study provides basic information about calcium transport in a plant pathogenic fungus as well as demonstrating a possible mode of action of a phytoalexin.
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Affiliation(s)
- J L Giannini
- Department of Agronomy, University of Illinois, Urbana 61801
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Giannini JL, Holt JS, Briskin DP. Isolation of sealed plasma membrane vesicles from Phytophthora megasperma f. sp. glycinea. I. Characterization of proton pumping and ATPase activity. Arch Biochem Biophys 1988; 265:337-45. [PMID: 2844118 DOI: 10.1016/0003-9861(88)90136-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Sealed vesicles were isolated from a plant pathogenic fungus Phytophthora megasperma f. sp. glycinea using a modification of a method previously developed for plant plasma membrane vesicle isolation. Vanadate-sensitive, proton pumping microsomal membrane vesicles were resolved on a linear sucrose density gradient and found to comigrate with a vanadate-sensitive ATPase. Both the proton pumping and ATPase activity of these vesicles had a pH optimum of 6.5 and demonstrated similar properties with respect to substrate specificity and inhibitor sensitivity. These properties were in agreement with previously published data on the Phytophthora plasma membrane ATPase. In contrast with previous reports there was no K+ stimulation of the plasma membrane ATPase and the Km for Mg:ATP (1:1 concentration ratio) was higher (2.5 mM). A comparison of anion (potassium salts) effects upon delta pH and delta psi formation in sealed Phytophthora plasma membrane vesicles revealed a correspondence between the relative ability of anions to stimulate proton transport and to reduce delta psi. The relative order for this effect was KCl greater than KBr much greater than KMes, KNO3, KClO3, K2SO4. This study presents a method for the isolation of sealed vesicles from Phytophthora hyphae. It also provides basic information on the plasma membrane H+-ATPase and its associated proton pumping activity.
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Affiliation(s)
- J L Giannini
- Department of Agronomy, University of Illinois, Urbana 61801
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Abstract
The potential role of pyridine nucleotide oxidation in the energization and/or regulation of membrane transport was examined using sealed plasma membrane vesicles isolated from red beet (Beta vulgaris L.) storage tissue. In this system, pyridine nucleotide oxidation, which was enhanced in the presence of ferricyanide, occurred. In the presence or absence of ferricyanide, the oxidation of NADH was several-fold greater than the oxidation of NADPH, indicating that it was the preferred substrate for oxidation in this system. Ferricyanide reduction coupled to NADH oxidation did not require the transmembrane movement of reducing equivalents since ferricyanide incorporated inside the vesicles could not be reduced by NADH added externally to the vesicles, unless the vesicles were made leaky by the addition of 0.05% (v/v) Triton X-100. Using fluorescent probes for the measurement of transmembrane pH gradients and membrane potentials, it was determined that NADH oxidation did not result in the production of a proton electrochemical gradient or have any effect upon the proton electrochemical gradient produced by the plasma membrane H+-ATPase. The oxidation of NADH in the presence of ferricyanide did result in the acidification of the reaction medium. This acidification was unaffected by the addition of Gramicidin D and stimulated by the addition of 0.05% (v/v) Triton X-100, suggesting a scalar (nonvectorial) production of protons in the oxidation/reduction reaction. The results of this study suggest that the oxidation of pyridine nucleotides by plasma membrane vesicles is not related to energization of transport at the plasma membrane or modulation of the activity of the plasma membrane H+-ATPase.
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Affiliation(s)
- J L Giannini
- Department of Agronomy, University of Illinois, Urbana 61801
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Giannini JL, Gildensoph LH, Reynolds-Niesman I, Briskin DP. Calcium Transport in Sealed Vesicles from Red Beet (Beta vulgaris L.) Storage Tissue : I. Characterization of a Ca-Pumping ATPase Associated with the Endoplasmic Reticulum. Plant Physiol 1987; 85:1129-36. [PMID: 16665816 PMCID: PMC1054406 DOI: 10.1104/pp.85.4.1129] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Calcium transport was examined in microsomal membrane vesicles from red beet (Beta vulgaris L.) storage tissue using chlorotetracycline as a fluorescent probe. This probe demonstrates an increase in fluorescence corresponding to calcium accumulation within the vesicles which can be collapsed by the addition of the calcium ionophore A23187. Calcium uptake in the microsomal vesicles was ATP dependent and completely inhibited by orthovanadate. Centrifugation of the microsomal membrane fraction on a linear 15 to 45% (w/w) sucrose density gradient revealed the presence of a single peak of calcium uptake which comigrated with the marker for endoplasmic reticulum. The calcium transport system associated with endoplasmic reticulum vesicles was then further characterized in fractions produced by centrifugation on discontinous sucrose density gradients. Calcium transport was insensitive to carbonylcyanide m-chlorophenylhydrazone indicating the presence of a primary transport system directly linked to ATP utilization. The endoplasmic reticulum vesicles contained an ATPase activity that was calcium dependent and further stimulated by A23187 (Ca(2+), A23187 stimulated-ATPase). Both calcium uptake and Ca(2+), A23187 stimulated ATPase demonstrated similar properties with respect to pH optimum, inhibitor sensitivity, substrate specificity, and substrate kinetics. Treatment of the red beet endoplasmic reticulum vesicles with [gamma-(32)P]-ATP over short time intervals revealed the presence of a rapidly turning over 96 kilodalton radioactive peptide possibly representing a phosphorylated intermediate of this endoplasmic reticulum associated ATPase. It is proposed that this ATPase activity may represent the enzymic machinery responsible for mediating primary calcium transport in the endoplasmic reticulum linked to ATP utilization.
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Affiliation(s)
- J L Giannini
- Department of Agronomy, University of Illinois, Urbana, Illinois 61801
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