1
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Mathew IE, Rhein HS, Yang J, Gradogna A, Carpaneto A, Guo Q, Tappero R, Scholz-Starke J, Barkla BJ, Hirschi KD, Punshon T. Sequential removal of cation/H + exchangers reveals their additive role in elemental distribution, calcium depletion and anoxia tolerance. Plant Cell Environ 2024; 47:557-573. [PMID: 37916653 DOI: 10.1111/pce.14756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 09/21/2023] [Accepted: 10/18/2023] [Indexed: 11/03/2023]
Abstract
Multiple Arabidopsis H+ /Cation exchangers (CAXs) participate in high-capacity transport into the vacuole. Previous studies have analysed single and double mutants that marginally reduced transport; however, assessing phenotypes caused by transport loss has proven enigmatic. Here, we generated quadruple mutants (cax1-4: qKO) that exhibited growth inhibition, an 85% reduction in tonoplast-localised H+ /Ca transport, and enhanced tolerance to anoxic conditions compared to CAX1 mutants. Leveraging inductively coupled plasma mass spectrometry (ICP-MS) and synchrotron X-ray fluorescence (SXRF), we demonstrate CAX transporters work together to regulate leaf elemental content: ICP-MS analysis showed that the elemental concentrations in leaves strongly correlated with the number of CAX mutations; SXRF imaging showed changes in element partitioning not present in single CAX mutants and qKO had a 40% reduction in calcium (Ca) abundance. Reduced endogenous Ca may promote anoxia tolerance; wild-type plants grown in Ca-limited conditions were anoxia tolerant. Sequential reduction of CAXs increased mRNA expression and protein abundance changes associated with reactive oxygen species and stress signalling pathways. Multiple CAXs participate in postanoxia recovery as their concerted removal heightened changes in postanoxia Ca signalling. This work showcases the integrated and diverse function of H+ /Cation transporters and demonstrates the ability to improve anoxia tolerance through diminishing endogenous Ca levels.
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Affiliation(s)
- Iny Elizebeth Mathew
- Pediatrics-Nutrition, Children's Nutrition Research, Baylor College of Medicine, Houston, Texas, USA
| | - Hormat Shadgou Rhein
- Pediatrics-Nutrition, Children's Nutrition Research, Baylor College of Medicine, Houston, Texas, USA
| | - Jian Yang
- Pediatrics-Nutrition, Children's Nutrition Research, Baylor College of Medicine, Houston, Texas, USA
| | - Antonella Gradogna
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Armando Carpaneto
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Genova, Italy
| | - Qi Guo
- Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
| | - Ryan Tappero
- Brookhaven National Laboratory, Photon Sciences Department, Upton, New York, USA
| | | | - Bronwyn J Barkla
- Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
| | - Kendal D Hirschi
- Pediatrics-Nutrition, Children's Nutrition Research, Baylor College of Medicine, Houston, Texas, USA
| | - Tracy Punshon
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
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2
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Maniero RA, Picco C, Hartmann A, Engelberger F, Gradogna A, Scholz-Starke J, Melzer M, Künze G, Carpaneto A, von Wirén N, Giehl RFH. Ferric reduction by a CYBDOM protein counteracts increased iron availability in root meristems induced by phosphorus deficiency. Nat Commun 2024; 15:422. [PMID: 38212310 PMCID: PMC10784544 DOI: 10.1038/s41467-023-43912-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 11/23/2023] [Indexed: 01/13/2024] Open
Abstract
To mobilize sparingly available phosphorus (P) in the rhizosphere, many plant species secrete malate to release P sorbed onto (hydr)oxides of aluminum and iron (Fe). In the presence of Fe, malate can provoke Fe over-accumulation in the root apoplast, triggering a series of events that inhibit root growth. Here, we identified HYPERSENSITIVE TO LOW P1 (HYP1), a CYBDOM protein constituted of a DOMON and a cytochrome b561 domain, as critical to maintain cell elongation and meristem integrity under low P. We demonstrate that HYP1 mediates ascorbate-dependent trans-plasma membrane electron transport and can reduce ferric and cupric substrates in Xenopus laevis oocytes and in planta. HYP1 expression is up-regulated in response to P deficiency in the proximal zone of the root apical meristem. Disruption of HYP1 leads to increased Fe and callose accumulation in the root meristem and causes significant transcriptional changes in roots. We further demonstrate that HYP1 activity overcomes malate-induced Fe accumulation, thereby preventing Fe-dependent root growth arrest in response to low P. Collectively, our results uncover an ascorbate-dependent metalloreductase that is critical to protect root meristems of P-deficient plants from increased Fe availability and provide insights into the physiological function of the yet poorly characterized but ubiquitous CYBDOM proteins.
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Affiliation(s)
- Rodolfo A Maniero
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany
| | - Cristiana Picco
- Institute of Biophysics, National Research Council, Via De Marini 16, 16149, Genoa, Italy
| | - Anja Hartmann
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany
| | - Felipe Engelberger
- Institute for Drug Discovery, Leipzig University, SAC 04103, Leipzig, Germany
| | - Antonella Gradogna
- Institute of Biophysics, National Research Council, Via De Marini 16, 16149, Genoa, Italy
| | - Joachim Scholz-Starke
- Institute of Biophysics, National Research Council, Via De Marini 16, 16149, Genoa, Italy
| | - Michael Melzer
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany
| | - Georg Künze
- Institute for Drug Discovery, Leipzig University, SAC 04103, Leipzig, Germany
- Center for Scalable Data Analytics and Artificial Intelligence, Leipzig University, 04105, Leipzig, Germany
- Interdisciplinary Center for Bioinformatics, Leipzig University, 04107, Leipzig, Germany
| | - Armando Carpaneto
- Institute of Biophysics, National Research Council, Via De Marini 16, 16149, Genoa, Italy
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Viale Benedetto XV 5, 16132, Genoa, Italy
| | - Nicolaus von Wirén
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany
| | - Ricardo F H Giehl
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany.
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3
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Khan A, Cheng J, Kitashova A, Fürtauer L, Nägele T, Picco C, Scholz-Starke J, Keller I, Neuhaus HE, Pommerrenig B. Vacuolar sugar transporter EARLY RESPONSE TO DEHYDRATION6-LIKE4 affects fructose signaling and plant growth. Plant Physiol 2023; 193:2141-2163. [PMID: 37427783 DOI: 10.1093/plphys/kiad403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 06/02/2023] [Accepted: 06/11/2023] [Indexed: 07/11/2023]
Abstract
Regulation of intracellular sugar homeostasis is maintained by regulation of activities of sugar import and export proteins residing at the tonoplast. We show here that the EARLY RESPONSE TO DEHYDRATION6-LIKE4 (ERDL4) protein, a member of the monosaccharide transporter family, resides in the vacuolar membrane in Arabidopsis (Arabidopsis thaliana). Gene expression and subcellular fractionation studies indicated that ERDL4 participates in fructose allocation across the tonoplast. Overexpression of ERDL4 increased total sugar levels in leaves due to a concomitantly induced stimulation of TONOPLAST SUGAR TRANSPORTER 2 (TST2) expression, coding for the major vacuolar sugar loader. This conclusion is supported by the finding that tst1-2 knockout lines overexpressing ERDL4 lack increased cellular sugar levels. ERDL4 activity contributing to the coordination of cellular sugar homeostasis is also indicated by 2 further observations. First, ERDL4 and TST genes exhibit an opposite regulation during a diurnal rhythm, and second, the ERDL4 gene is markedly expressed during cold acclimation, representing a situation in which TST activity needs to be upregulated. Moreover, ERDL4-overexpressing plants show larger rosettes and roots, a delayed flowering time, and increased total seed yield. Consistently, erdl4 knockout plants show impaired cold acclimation and freezing tolerance along with reduced plant biomass. In summary, we show that modification of cytosolic fructose levels influences plant organ development and stress tolerance.
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Affiliation(s)
- Azkia Khan
- Plant Physiology, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 22, D-67653 Kaiserslautern, Germany
| | - Jintao Cheng
- College of Horticulture and Forestry Sciences, Huazhong Agricultural University and Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan 430070, China
| | - Anastasia Kitashova
- Plant Evolutionary Cell Biology, Faculty of Biology, Ludwig-Maximilians- Universität München, D-82152 Planegg-Martinsried, Germany
| | - Lisa Fürtauer
- Institute for Biology III, Unit of Plant Molecular Systems Biology, RWTH Aachen University, Aachen, Germany
| | - Thomas Nägele
- Plant Evolutionary Cell Biology, Faculty of Biology, Ludwig-Maximilians- Universität München, D-82152 Planegg-Martinsried, Germany
| | - Cristiana Picco
- Institute of Biophysics, Consiglio Nazionale delle Ricerche (CNR), Via De Marini 6, I-16149 Genova, Italy
| | - Joachim Scholz-Starke
- Institute of Biophysics, Consiglio Nazionale delle Ricerche (CNR), Via De Marini 6, I-16149 Genova, Italy
| | - Isabel Keller
- Plant Physiology, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 22, D-67653 Kaiserslautern, Germany
| | - H Ekkehard Neuhaus
- Plant Physiology, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 22, D-67653 Kaiserslautern, Germany
| | - Benjamin Pommerrenig
- Plant Physiology, RPTU Kaiserslautern-Landau, Paul-Ehrlich Straße 22, D-67653 Kaiserslautern, Germany
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4
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Gradogna A, Lagostena L, Beltrami S, Tosato E, Picco C, Scholz-Starke J, Sparla F, Trost P, Carpaneto A. Tonoplast cytochrome b561 is a transmembrane ascorbate-dependent monodehydroascorbate reductase: functional characterization of electron currents in plant vacuoles. New Phytol 2023; 238:1957-1971. [PMID: 36806214 DOI: 10.1111/nph.18823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 09/01/2022] [Accepted: 02/14/2023] [Indexed: 05/04/2023]
Abstract
Ascorbate (Asc) is a major redox buffer of plant cells, whose antioxidant activity depends on the ratio with its one-electron oxidation product monodehydroascorbate (MDHA). The cytoplasm contains millimolar concentrations of Asc and soluble enzymes that can regenerate Asc from MDHA or fully oxidized dehydroascorbate. Also, vacuoles contain Asc, but no soluble Asc-regenerating enzymes. Here, we show that vacuoles isolated from Arabidopsis mesophyll cells contain a tonoplast electron transport system that works as a reversible, Asc-dependent transmembrane MDHA oxidoreductase. Electron currents were measured by patch-clamp on isolated vacuoles and found to depend on the availability of Asc (electron donor) and ferricyanide or MDHA (electron acceptors) on opposite sides of the tonoplast. Electron currents were catalyzed by cytochrome b561 isoform A (CYB561A), a tonoplast redox protein with cytoplasmic and luminal Asc binding sites. The Km for Asc of the luminal (4.5 mM) and cytoplasmic site (51 mM) reflected the physiological Asc concentrations in these compartments. The maximal current amplitude was similar in both directions. Mutant plants with impaired CYB561A expression showed no detectable trans-tonoplast electron currents and strong accumulation of leaf anthocyanins under excessive illumination, suggesting a redox-modulation exerted by CYB561A on the typical anthocyanin response to high-light stress.
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Affiliation(s)
| | - Laura Lagostena
- Institute of Biophysics - CNR, Via De Marini 6, 16149, Genova, Italy
| | - Sara Beltrami
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Via Irnerio 42, 40126, Bologna, Italy
| | - Edoardo Tosato
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Via Irnerio 42, 40126, Bologna, Italy
| | - Cristiana Picco
- Institute of Biophysics - CNR, Via De Marini 6, 16149, Genova, Italy
| | | | - Francesca Sparla
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Via Irnerio 42, 40126, Bologna, Italy
| | - Paolo Trost
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Via Irnerio 42, 40126, Bologna, Italy
| | - Armando Carpaneto
- Institute of Biophysics - CNR, Via De Marini 6, 16149, Genova, Italy
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Viale Benedetto XV 5, 16132, Genova, Italy
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5
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Boccaccio A, Picco C, Di Zanni E, Scholz-Starke J. Phospholipid scrambling by a TMEM16 homolog of Arabidopsis thaliana. FEBS J 2021; 289:2578-2592. [PMID: 34775680 PMCID: PMC9299152 DOI: 10.1111/febs.16279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 06/18/2021] [Revised: 09/15/2021] [Accepted: 11/12/2021] [Indexed: 12/20/2022]
Abstract
Membrane asymmetry is important for cellular physiology and established by energy‐dependent unidirectional lipid translocases, which have diverse physiological functions in plants. By contrast, the role of phospholipid scrambling (PLS), the passive bidirectional lipid transfer leading to the break‐down of membrane asymmetry, is currently still unexplored. The Arabidopsis thaliana genome contains a single gene (At1g73020) with homology to the eukaryotic TMEM16 family of Ca2+‐activated phospholipid scramblases. Here, we investigated the protein function of this Arabidopsis homolog. Fluorescent AtTMEM16 fusions localized to the ER both in transiently expressing Arabidopsis protoplasts and HEK293 cells. A putative scrambling domain (SCRD) was identified on the basis of sequence conservation and conferred PLS to transfected HEK293 cells, when grafted into the backbone of the non‐scrambling plasma membrane‐localized TMEM16A chloride channel. Finally, AtTMEM16 ‘gain‐of‐function’ variants gave rise to cellular phenotypes typical of aberrant scramblase activity, which were reversed by the additional introduction of a ‘loss‐of‐function’ mutation into the SCRD. In conclusion, our data suggest AtTMEM16 works as an ER‐resident lipid scramblase in Arabidopsis.
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Affiliation(s)
- Anna Boccaccio
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Cristiana Picco
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Eleonora Di Zanni
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
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6
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Gradogna A, Scholz-Starke J, Pardo JM, Carpaneto A. Beyond the patch-clamp resolution: functional activity of nonelectrogenic vacuolar NHX proton/potassium antiporters and inhibition by phosphoinositides. New Phytol 2021; 229:3026-3036. [PMID: 33098586 DOI: 10.1111/nph.17021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 07/29/2020] [Accepted: 10/12/2020] [Indexed: 05/12/2023]
Abstract
We combined the patch-clamp technique with ratiometric fluorescence imaging using the proton-responsive dye BCECF as a luminal probe. Upon application of a steep cytosol-directed potassium ion (K+ ) gradient in Arabidopsis mesophyll vacuoles, a strong and reversible acidification of the vacuolar lumen was detected, whereas no associated electrical currents were observed, in agreement with electroneutral cation/H+ exchange. Our data show that this acidification was generated by NHX antiport activity, because: it did not distinguish between K+ and sodium (Na+ ) ions; it was sensitive to the NHX inhibitor benzamil; and it was completely absent in vacuoles from nhx1 nhx2 double knockout plants. Our data further show that NHX activity could be reversed, was voltage-independent and specifically impaired by the low-abundance signaling lipid PI(3,5)P2 , which may regulate salt accumulation in plants by acting as a common messenger to coordinately shut down secondary active carriers responsible for cation and anion uptake inside the vacuole. Finally, we developed a theory based on thermodynamics, which supports the data obtained by our novel experimental approach. This work, therefore, represents a proof-of-principle that can be applied to the study of proton-dependent exchangers from plants and animals, which are barely detectable using conventional techniques.
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Affiliation(s)
- Antonella Gradogna
- Institute of Biophysics, National Research Council, Via De Marini 6, Genova, 16149, Italy
| | - Joachim Scholz-Starke
- Institute of Biophysics, National Research Council, Via De Marini 6, Genova, 16149, Italy
| | - José M Pardo
- Institute of Plant Biochemistry and Photosynthesis, CSIC-University of Seville, Seville, 41092, Spain
| | - Armando Carpaneto
- Institute of Biophysics, National Research Council, Via De Marini 6, Genova, 16149, Italy
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Viale Benedetto XV 5, Genova, 16132, Italy
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7
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Di Zanni E, Gradogna A, Picco C, Scholz-Starke J, Boccaccio A. TMEM16E/ANO5 mutations related to bone dysplasia or muscular dystrophy cause opposite effects on lipid scrambling. Hum Mutat 2020; 41:1157-1170. [PMID: 32112655 DOI: 10.1002/humu.24006] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 02/21/2020] [Accepted: 02/25/2020] [Indexed: 12/14/2022]
Abstract
Mutations in the human TMEM16E/ANO5 gene are causative for gnathodiaphyseal dysplasia (GDD), a rare bone malformation and fragility disorder, and for two types of muscular dystrophy (MD). Previous studies have demonstrated that TMEM16E/ANO5 is a Ca2+ -activated phospholipid scramblase and that the mutation c.1538C>T (p.Thr513Ile) causing GDD leads to a gain-of-function phenotype. Here, using established HEK293-based functional assays, we investigated the effects of MD-related and further GDD-related amino acid exchanges on TMEM16E/ANO5 function in the same expression system. These experiments also revealed that the gradual changes in HEK293 cell morphology observed upon expression of TMEM16E/ANO5GDD mutants are a consequence of aberrant protein activity. Our results collectively demonstrate that, on the level of protein function, MD mutations are associated to loss-of-function and GDD mutations to gain-of-function phenotypes, confirming conjectures made on the basis of inheritance modes.
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Affiliation(s)
- Eleonora Di Zanni
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Antonella Gradogna
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Cristiana Picco
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | | | - Anna Boccaccio
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
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8
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Primo C, Pizzio GA, Yang J, Gaxiola RA, Scholz-Starke J, Hirschi KD. Plant proton pumping pyrophosphatase: the potential for its pyrophosphate synthesis activity to modulate plant growth. Plant Biol (Stuttg) 2019; 21:989-996. [PMID: 31081197 DOI: 10.1111/plb.13007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [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: 03/21/2019] [Accepted: 05/09/2019] [Indexed: 05/25/2023]
Abstract
Cellular pyrophosphate (PPi) homeostasis is vital for normal plant growth and development. Plant proton-pumping pyrophosphatases (H+ -PPases) are enzymes with different tissue-specific functions related to the regulation of PPi homeostasis. Enhanced expression of plant H+ -PPases increases biomass and yield in different crop species. Here, we emphasise emerging studies utilising heterologous expression in yeast and plant vacuole electrophysiology approaches, as well as phylogenetic relationships and structural analysis, to showcase that the H+ -PPases possess a PPi synthesis function. We postulate this synthase activity contributes to modulating and promoting plant growth both in H+ -PPase-engineered crops and in wild-type plants. We propose a model where the PPi synthase activity of H+ -PPases maintains the PPi pool when cells adopt PPi-dependent glycolysis during high energy demands and/or low oxygen environments. We conclude by proposing experiments to further investigate the H+ -PPase-mediated PPi synthase role in plant growth.
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Affiliation(s)
- C Primo
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA
| | - G A Pizzio
- Center for Research in Agricultural Genomics, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
| | - J Yang
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA
| | - R A Gaxiola
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - J Scholz-Starke
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - K D Hirschi
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA
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9
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Affiliation(s)
- Anna Boccaccio
- a Institute of Biophysics , Consiglio Nazionale delle Ricerche (CNR) , Genova , Italy
| | - Eleonora Di Zanni
- a Institute of Biophysics , Consiglio Nazionale delle Ricerche (CNR) , Genova , Italy
| | - Antonella Gradogna
- a Institute of Biophysics , Consiglio Nazionale delle Ricerche (CNR) , Genova , Italy
| | - Joachim Scholz-Starke
- a Institute of Biophysics , Consiglio Nazionale delle Ricerche (CNR) , Genova , Italy
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10
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Di Zanni E, Gradogna A, Picco C, Scholz-Starke J, Boccaccio A. Phospholipid Scrambling Activity by TMEM16E/Ano5: Opposite Effects of Mutations Causing Bone Dysplasia and Muscular Dystrophy. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.1229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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11
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Rocchi A, Moretti D, Lignani G, Colombo E, Scholz-Starke J, Baldelli P, Tkatch T, Benfenati F. Neurite-Enriched MicroRNA-218 Stimulates Translation of the GluA2 Subunit and Increases Excitatory Synaptic Strength. Mol Neurobiol 2019; 56:5701-5714. [DOI: 10.1007/s12035-019-1492-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 01/10/2019] [Indexed: 12/19/2022]
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12
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Scholz-Starke J, Primo C, Yang J, Kandel R, Gaxiola RA, Hirschi KD. The flip side of the Arabidopsis type I proton-pumping pyrophosphatase (AVP1): Using a transmembrane H + gradient to synthesize pyrophosphate. J Biol Chem 2018; 294:1290-1299. [PMID: 30510138 DOI: 10.1074/jbc.ra118.006315] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/29/2018] [Indexed: 01/19/2023] Open
Abstract
Energy partitioning and plant growth are mediated in part by a type I H+-pumping pyrophosphatase (H+-PPase). A canonical role for this transporter has been demonstrated at the tonoplast where it serves a job-sharing role with V-ATPase in vacuolar acidification. Here, we investigated whether the plant H+-PPase from Arabidopsis also functions in "reverse mode" to synthesize PPi using the transmembrane H+ gradient. Using patch-clamp recordings on Arabidopsis vacuoles, we observed inward currents upon Pi application on the cytosolic side. These currents were strongly reduced in vacuoles from two independent H+-PPase mutant lines (vhp1-1 and fugu5-1) lacking the classical PPi-induced outward currents related to H+ pumping, whereas they were significantly larger in vacuoles with engineered heightened expression of the H+-PPase. Current amplitudes related to reverse-mode H+ transport depended on the membrane potential, cytosolic Pi concentration, and magnitude of the pH gradient across the tonoplast. Of note, experiments on vacuolar membrane-enriched vesicles isolated from yeast expressing the Arabidopsis H+-PPase (AVP1) demonstrated Pi-dependent PPi synthase activity in the presence of a pH gradient. Our work establishes that a plant H+-PPase can operate as a PPi synthase beyond its canonical role in vacuolar acidification and cytosolic PPi scavenging. We propose that the PPi synthase activity of H+-PPase contributes to a cascade of events that energize plant growth.
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Affiliation(s)
- Joachim Scholz-Starke
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Via De Marini 6, 16149 Genova, Italy.
| | - Cecilia Primo
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030
| | - Jian Yang
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030
| | - Raju Kandel
- School of Life Sciences, Arizona State University, Tempe, Arizona 85287
| | - Roberto A Gaxiola
- School of Life Sciences, Arizona State University, Tempe, Arizona 85287
| | - Kendal D Hirschi
- Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030.
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Böhm J, Messerer M, Müller HM, Scholz-Starke J, Gradogna A, Scherzer S, Maierhofer T, Bazihizina N, Zhang H, Stigloher C, Ache P, Al-Rasheid KAS, Mayer KFX, Shabala S, Carpaneto A, Haberer G, Zhu JK, Hedrich R. Understanding the Molecular Basis of Salt Sequestration in Epidermal Bladder Cells of Chenopodium quinoa. Curr Biol 2018; 28:3075-3085.e7. [PMID: 30245105 DOI: 10.1016/j.cub.2018.08.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/20/2018] [Accepted: 08/01/2018] [Indexed: 02/03/2023]
Abstract
Soil salinity is destroying arable land and is considered to be one of the major threats to global food security in the 21st century. Therefore, the ability of naturally salt-tolerant halophyte plants to sequester large quantities of salt in external structures, such as epidermal bladder cells (EBCs), is of great interest. Using Chenopodium quinoa, a pseudo-cereal halophyte of great economic potential, we have shown previously that, upon removal of salt bladders, quinoa becomes salt sensitive. In this work, we analyzed the molecular mechanism underlying the unique salt dumping capabilities of bladder cells in quinoa. The transporters differentially expressed in the EBC transcriptome and functional electrophysiological testing of key EBC transporters in Xenopus oocytes revealed that loading of Na+ and Cl- into EBCs is mediated by a set of tailored plasma and vacuole membrane-based sodium-selective channel and chloride-permeable transporter.
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Affiliation(s)
- Jennifer Böhm
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia
| | - Maxim Messerer
- Plant Genome and Systems Biology, Helmholtz Center Munich, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Heike M Müller
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany
| | - Joachim Scholz-Starke
- Institute of Biophysics, National Research Council (CNR), Via De Marini 6, 16149 Genova, Italy
| | - Antonella Gradogna
- Institute of Biophysics, National Research Council (CNR), Via De Marini 6, 16149 Genova, Italy
| | - Sönke Scherzer
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany
| | - Tobias Maierhofer
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany
| | - Nadia Bazihizina
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia; Department of Agrifood Production and Environmental Sciences, Università degli Studi di Firenze, Viale delle Idee 30, 50019 Sesto Fiorentino, Florence, Italy
| | - Heng Zhang
- Shanghai Center for Plant Stress Biology, and CAS Center for Excellence in Molecular Plant Sciences, 3888 Chenhua Road, Shanghai 201602, China
| | - Christian Stigloher
- Imaging Core Facility, Biocenter, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany
| | - Peter Ache
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany
| | - Khaled A S Al-Rasheid
- Zoology Department, College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia
| | - Klaus F X Mayer
- Plant Genome and Systems Biology, Helmholtz Center Munich, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Sergey Shabala
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia; Department of Horticulture, Foshan University, Foshan 528000, PRC
| | - Armando Carpaneto
- Institute of Biophysics, National Research Council (CNR), Via De Marini 6, 16149 Genova, Italy; Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Viale Benedetto XV 5, 16132 Genova, Italy
| | - Georg Haberer
- Plant Genome and Systems Biology, Helmholtz Center Munich, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology, and CAS Center for Excellence in Molecular Plant Sciences, 3888 Chenhua Road, Shanghai 201602, China; Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA.
| | - Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, University of Wuerzburg, Julius-von-Sachs Platz 2, 97082 Wuerzburg, Germany.
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Di Zanni E, Gradogna A, Scholz-Starke J, Boccaccio A. Gain-of-Function of TMEM16E/ANO5 Scrambling Activity Caused by a Mutation Associated with the Bone Genetic Disease Gnathodiaphyseal Dysplasia. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Di Zanni E, Gradogna A, Scholz-Starke J, Boccaccio A. Gain of function of TMEM16E/ANO5 scrambling activity caused by a mutation associated with gnathodiaphyseal dysplasia. Cell Mol Life Sci 2017; 75:1657-1670. [PMID: 29124309 PMCID: PMC5897490 DOI: 10.1007/s00018-017-2704-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [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: 06/22/2017] [Revised: 10/10/2017] [Accepted: 10/30/2017] [Indexed: 12/31/2022]
Abstract
Mutations in the human TMEM16E (ANO5) gene are associated both with the bone disease gnathodiaphyseal dysplasia (GDD; OMIM: 166260) and muscle dystrophies (OMIM: 611307, 613319). However, the physiological function of TMEM16E has remained unclear. We show here that human TMEM16E, when overexpressed in mammalian cell lines, displayed partial plasma membrane localization and gave rise to phospholipid scrambling (PLS) as well as non-selective ionic currents with slow time-dependent activation at highly depolarized membrane potentials. While the activity of wild-type TMEM16E depended on elevated cytosolic Ca2+ levels, a mutant form carrying the GDD-causing T513I substitution showed PLS and large time-dependent ion currents even at low cytosolic Ca2+ concentrations. Contrarily, mutation of the homologous position in the Ca2+-activated Cl− channel TMEM16B paralog hardly affected its function. In summary, these data provide the first direct demonstration of Ca2+-dependent PLS activity for TMEM16E and suggest a gain-of-function phenotype related to a GDD mutation.
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Affiliation(s)
- Eleonora Di Zanni
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Via de Marini 6, 16149, Genova, Italy
| | - Antonella Gradogna
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Via de Marini 6, 16149, Genova, Italy
| | - Joachim Scholz-Starke
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Via de Marini 6, 16149, Genova, Italy.
| | - Anna Boccaccio
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Via de Marini 6, 16149, Genova, Italy.
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16
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Carpaneto A, Boccaccio A, Lagostena L, Di Zanni E, Scholz-Starke J. The signaling lipid phosphatidylinositol-3,5-bisphosphate targets plant CLC-a anion/H + exchange activity. EMBO Rep 2017; 18:1100-1107. [PMID: 28536248 DOI: 10.15252/embr.201643814] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 04/20/2017] [Accepted: 04/21/2017] [Indexed: 12/21/2022] Open
Abstract
Phosphatidylinositol-3,5-bisphosphate (PI(3,5)P2) is a low-abundance signaling lipid associated with endo-lysosomal and vacuolar membranes in eukaryotic cells. Recent studies on Arabidopsis indicated a critical role of PI(3,5)P2 in vacuolar acidification and morphology during ABA-induced stomatal closure, but the molecular targets in plant cells remained unknown. By using patch-clamp recordings on Arabidopsis vacuoles, we show here that PI(3,5)P2 does not affect the activity of vacuolar H+-pyrophosphatase or vacuolar H+-ATPase. Instead, PI(3,5)P2 at low nanomolar concentrations inhibited an inwardly rectifying conductance, which appeared upon vacuolar acidification elicited by prolonged H+ pumping activity. We provide evidence that this novel conductance is mediated by chloride channel a (CLC-a), a member of the anion/H+ exchanger family formerly implicated in stomatal movements in Arabidopsis H+-dependent currents were absent in clc-a knock-out vacuoles, and canonical CLC-a-dependent nitrate/H+ antiport was inhibited by low concentrations of PI(3,5)P2 Finally, using the pH indicator probe BCECF, we show that CLC-a inhibition contributes to vacuolar acidification. These data provide a mechanistic explanation for the essential role of PI(3,5)P2 and advance our knowledge about the regulation of vacuolar ion transport.
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Affiliation(s)
- Armando Carpaneto
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Anna Boccaccio
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Laura Lagostena
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Eleonora Di Zanni
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
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Scholz-Starke J, Cesca F. Stepping Out of the Shade: Control of Neuronal Activity by the Scaffold Protein Kidins220/ARMS. Front Cell Neurosci 2016; 10:68. [PMID: 27013979 PMCID: PMC4789535 DOI: 10.3389/fncel.2016.00068] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [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: 12/29/2015] [Accepted: 03/01/2016] [Indexed: 12/31/2022] Open
Abstract
The correct functioning of the nervous system depends on the exquisitely fine control of neuronal excitability and synaptic plasticity, which relies on an intricate network of protein-protein interactions and signaling that shapes neuronal homeostasis during development and in adulthood. In this complex scenario, Kinase D interacting substrate of 220 kDa/ankyrin repeat-rich membrane spanning (Kidins220/ARMS) acts as a multi-functional scaffold protein with preferential expression in the nervous system. Engaged in a plethora of interactions with membrane receptors, cytosolic signaling components and cytoskeletal proteins, Kidins220/ARMS is implicated in numerous cellular functions including neuronal survival, neurite outgrowth and maturation and neuronal activity, often in the context of neurotrophin (NT) signaling pathways. Recent studies have highlighted a number of cell- and context-specific roles for this protein in the control of synaptic transmission and neuronal excitability, which are at present far from being completely understood. In addition, some evidence has began to emerge, linking alterations of Kidins220 expression to the onset of various neurodegenerative diseases and neuropsychiatric disorders. In this review, we present a concise summary of our fragmentary knowledge of Kidins220/ARMS biological functions, focusing on the mechanism(s) by which it controls various aspects of neuronal activity. We have tried, where possible, to discuss the available evidence in the wider context of NT-mediated regulation, and to outline emerging roles of Kidins220/ARMS in human pathologies.
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Affiliation(s)
| | - Fabrizia Cesca
- Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia Genova, Italy
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Picco C, Scholz-Starke J, Festa M, Costa A, Sparla F, Trost P, Carpaneto A. Direct Recording of Trans-Plasma Membrane Electron Currents Mediated by a Member of the Cytochrome b561 Family of Soybean. Plant Physiol 2015; 169:986-95. [PMID: 26282237 PMCID: PMC4587454 DOI: 10.1104/pp.15.00642] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 08/12/2015] [Indexed: 05/20/2023]
Abstract
Trans-plasma membrane electron transfer is achieved by b-type cytochromes of different families, and plays a fundamental role in diverse cellular processes involving two interacting redox couples that are physically separated by a phospholipid bilayer, such as iron uptake and redox signaling. Despite their importance, no direct recordings of trans-plasma membrane electron currents have been described in plants. In this work, we provide robust electrophysiological evidence of trans-plasma membrane electron flow mediated by a soybean (Glycine max) cytochrome b561 associated with a dopamine β-monooxygenase redox domain (CYBDOM), which localizes to the plasma membrane in transgenic Arabidopsis (Arabidopsis thaliana) plants and CYBDOM complementary RNA-injected Xenopus laevis oocytes. In oocytes, two-electrode voltage clamp experiments showed that CYBDOM-mediated currents were activated by extracellular electron acceptors in a concentration- and type-specific manner. Current amplitudes were voltage dependent, strongly potentiated in oocytes preinjected with ascorbate (the canonical electron donor for cytochrome b561), and abolished by mutating a highly conserved His residue (H292L) predicted to coordinate the cytoplasmic heme b group. We believe that this unique approach opens new perspectives in plant transmembrane electron transport and beyond.
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Affiliation(s)
- Cristiana Picco
- Institute of Biophysics, Consiglio National Research Council, 16149 Genova, Italy (C.P., J.S.-S., M.F., A.Ca.);Department of Biosciences, University of Milan, 20133 Milan, Italy (A.Co.);Institute of Biophysics, Consiglio Nazionale delle Ricerche, 20133 Milan, Italy (A.Co.); andDepartment of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy (F.S., P.T.)
| | - Joachim Scholz-Starke
- Institute of Biophysics, Consiglio National Research Council, 16149 Genova, Italy (C.P., J.S.-S., M.F., A.Ca.);Department of Biosciences, University of Milan, 20133 Milan, Italy (A.Co.);Institute of Biophysics, Consiglio Nazionale delle Ricerche, 20133 Milan, Italy (A.Co.); andDepartment of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy (F.S., P.T.)
| | - Margherita Festa
- Institute of Biophysics, Consiglio National Research Council, 16149 Genova, Italy (C.P., J.S.-S., M.F., A.Ca.);Department of Biosciences, University of Milan, 20133 Milan, Italy (A.Co.);Institute of Biophysics, Consiglio Nazionale delle Ricerche, 20133 Milan, Italy (A.Co.); andDepartment of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy (F.S., P.T.)
| | - Alex Costa
- Institute of Biophysics, Consiglio National Research Council, 16149 Genova, Italy (C.P., J.S.-S., M.F., A.Ca.);Department of Biosciences, University of Milan, 20133 Milan, Italy (A.Co.);Institute of Biophysics, Consiglio Nazionale delle Ricerche, 20133 Milan, Italy (A.Co.); andDepartment of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy (F.S., P.T.)
| | - Francesca Sparla
- Institute of Biophysics, Consiglio National Research Council, 16149 Genova, Italy (C.P., J.S.-S., M.F., A.Ca.);Department of Biosciences, University of Milan, 20133 Milan, Italy (A.Co.);Institute of Biophysics, Consiglio Nazionale delle Ricerche, 20133 Milan, Italy (A.Co.); andDepartment of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy (F.S., P.T.)
| | - Paolo Trost
- Institute of Biophysics, Consiglio National Research Council, 16149 Genova, Italy (C.P., J.S.-S., M.F., A.Ca.);Department of Biosciences, University of Milan, 20133 Milan, Italy (A.Co.);Institute of Biophysics, Consiglio Nazionale delle Ricerche, 20133 Milan, Italy (A.Co.); andDepartment of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy (F.S., P.T.)
| | - Armando Carpaneto
- Institute of Biophysics, Consiglio National Research Council, 16149 Genova, Italy (C.P., J.S.-S., M.F., A.Ca.);Department of Biosciences, University of Milan, 20133 Milan, Italy (A.Co.);Institute of Biophysics, Consiglio Nazionale delle Ricerche, 20133 Milan, Italy (A.Co.); andDepartment of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy (F.S., P.T.)
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Pottier M, Oomen R, Picco C, Giraudat J, Scholz-Starke J, Richaud P, Carpaneto A, Thomine S. Identification of mutations allowing Natural Resistance Associated Macrophage Proteins (NRAMP) to discriminate against cadmium. Plant J 2015; 83:625-37. [PMID: 26088788 DOI: 10.1111/tpj.12914] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [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: 03/02/2015] [Revised: 06/03/2015] [Accepted: 06/09/2015] [Indexed: 05/18/2023]
Abstract
Each essential transition metal plays a specific role in metabolic processes and has to be selectively transported. Living organisms need to discriminate between essential and non-essential metals such as cadmium (Cd(2+) ), which is highly toxic. However, transporters of the natural resistance-associated macrophage protein (NRAMP) family, which are involved in metal uptake and homeostasis, generally display poor selectivity towards divalent metal cations. In the present study we used a unique combination of yeast-based selection, electrophysiology on Xenopus oocytes and plant phenotyping to identify and characterize mutations that allow plant and mammalian NRAMP transporters to discriminate between their metal substrates. We took advantage of the increased Cd(2+) sensitivity of yeast expressing AtNRAMP4 to select mutations that decrease Cd(2+) sensitivity while maintaining the ability of AtNRAMP4 to transport Fe(2+) in a population of randomly mutagenized AtNRAMP4 cDNAs. The selection identified mutations in three residues. Among the selected mutations, several affect Zn(2+) transport, whereas only one, E401K, impairs Mn(2+) transport by AtNRAMP4. Introduction of the mutation F413I, located in a highly conserved domain, into the mammalian DMT1 transporter indicated that the importance of this residue in metal selectivity is conserved among NRAMP transporters from plant and animal kingdoms. Analyses of overexpressing plants showed that AtNRAMP4 affects the accumulation of metals in roots. Interestingly, the mutations selectively modify Cd(2+) and Zn(2+) accumulation without affecting Fe transport mediated by NRAMP4 in planta. This knowledge may be applicable for limiting Cd(2+) transport by other NRAMP transporters from animals or plants.
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Affiliation(s)
- Mathieu Pottier
- Institute for Integrative Biology of the Cell (I2BC), Saclay Plant Sciences, Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, Gif-sur-Yvette, F-91198, France
| | - Ronald Oomen
- Institute for Integrative Biology of the Cell (I2BC), Saclay Plant Sciences, Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, Gif-sur-Yvette, F-91198, France
| | | | - Jérôme Giraudat
- Institute for Integrative Biology of the Cell (I2BC), Saclay Plant Sciences, Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, Gif-sur-Yvette, F-91198, France
| | | | - Pierre Richaud
- Laboratoire de Bioénergie et Biotechnologie des Bactéries et Microalgues, CEA, DSV, IBEB, Saint-Paul-lès-Durance, F-13108, France
- CNRS, UMR Biol Veget et Microbiol Environ, Saint-Paul-lès-Durance, F-13108, France
- Aix-Marseille Université, Saint-Paul-lès-Durance, F-13108, France
| | | | - Sébastien Thomine
- Institute for Integrative Biology of the Cell (I2BC), Saclay Plant Sciences, Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, Gif-sur-Yvette, F-91198, France
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Cesca F, Satapathy A, Ferrea E, Nieus T, Benfenati F, Scholz-Starke J. Functional Interaction between the Scaffold Protein Kidins220/ARMS and Neuronal Voltage-Gated Na+ Channels. J Biol Chem 2015; 290:18045-18055. [PMID: 26037926 DOI: 10.1074/jbc.m115.654699] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Indexed: 12/19/2022] Open
Abstract
Kidins220 (kinase D-interacting substrate of 220 kDa)/ankyrin repeat-rich membrane spanning (ARMS) acts as a signaling platform at the plasma membrane and is implicated in a multitude of neuronal functions, including the control of neuronal activity. Here, we used the Kidins220(-/-) mouse model to study the effects of Kidins220 ablation on neuronal excitability. Multielectrode array recordings showed reduced evoked spiking activity in Kidins220(-/-) hippocampal networks, which was compatible with the increased excitability of GABAergic neurons determined by current-clamp recordings. Spike waveform analysis further indicated an increased sodium conductance in this neuronal subpopulation. Kidins220 association with brain voltage-gated sodium channels was shown by co-immunoprecipitation experiments and Na(+) current recordings in transfected HEK293 cells, which revealed dramatic alterations of kinetics and voltage dependence. Finally, an in silico interneuronal model incorporating the Kidins220-induced Na(+) current alterations reproduced the firing phenotype observed in Kidins220(-/-) neurons. These results identify Kidins220 as a novel modulator of Nav channel activity, broadening our understanding of the molecular mechanisms regulating network excitability.
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Affiliation(s)
- Fabrizia Cesca
- Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia, 16163 Genova, Italy.
| | - Annyesha Satapathy
- Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Department of Experimental Medicine, University of Genova, 16132 Genova, Italy
| | - Enrico Ferrea
- Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Sensorimotor Group, German Primate Center, 37077 Göttingen, Germany
| | - Thierry Nieus
- Neuro Technology Department, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Department of Experimental Medicine, University of Genova, 16132 Genova, Italy
| | - Joachim Scholz-Starke
- Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Institute of Biophysics, Consiglio Nazionale delle Ricerche, 16149 Genova, Italy.
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Picco C, Scholz-Starke J, Naso A, Preger V, Sparla F, Trost P, Carpaneto A. How are cytochrome b561 electron currents controlled by membrane voltage and substrate availability? Antioxid Redox Signal 2014; 21:384-91. [PMID: 24410448 DOI: 10.1089/ars.2013.5809] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Direct recordings of electron currents mediated by cytochromes b561 (CYB561) are not available yet, despite the importance of these proteins in a variety of physiological functions, including neurotransmitter synthesis and dietary iron uptake. Here, we used the two-electrode voltage-clamp technique applied to Xenopus oocytes to demonstrate, for the first time, the generation of electron currents by a Drosophila member of the CYB561 superfamily named stromal cell-derived receptor 2 (SDR2). This experimental method, along with the theoretical development of a three-state kinetic model, supports the hypothesis that electron donor/acceptor concentrations and transmembrane voltage mutually control SDR2-mediated electron transport activity in a complex but predictable manner.
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Boccaccio A, Scholz-Starke J, Hamamoto S, Larisch N, Festa M, Gutla PVK, Costa A, Dietrich P, Uozumi N, Carpaneto A. The phosphoinositide PI(3,5)P2 mediates activation of mammalian but not plant TPC proteins: functional expression of endolysosomal channels in yeast and plant cells. Cell Mol Life Sci 2014; 71:4275-83. [DOI: 10.1007/s00018-014-1623-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/18/2014] [Accepted: 03/31/2014] [Indexed: 11/29/2022]
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Costa A, Gutla PVK, Boccaccio A, Scholz-Starke J, Festa M, Basso B, Zanardi I, Pusch M, Schiavo FL, Gambale F, Carpaneto A. The Arabidopsis central vacuole as an expression system for intracellular transporters: functional characterization of the Cl-/H+ exchanger CLC-7. J Physiol 2012; 590:3421-30. [PMID: 22641774 DOI: 10.1113/jphysiol.2012.230227] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Functional characterization of intracellular transporters is hampered by the inaccessibility of animal endomembranes to standard electrophysiological techniques. Here, we used Arabidopsis mesophyll protoplasts as a novel heterologous expression system for the lysosomal chloride–proton exchanger CLC-7 from rat. Following transient expression of a rCLC-7:EGFP construct in isolated protoplasts, the fusion protein efficiently targeted to the membrane of the large central vacuole, the lytic compartment of plant cells. Membrane currents recorded from EGFP-positive vacuoles were almost voltage independent and showed time-dependent activation at elevated positive membrane potentials as a hallmark. The shift in the reversal potential of the current induced by a decrease of cytosolic pH was compatible with a 2Cl(-)/1H(+) exchange stoichiometry. Mutating the so-called gating glutamate into alanine (E245A) uncoupled chloride fluxes from the movement of protons, transforming the transporter into a chloride channel-like protein. Importantly, CLC-7 transport activity in the vacuolar expression system was recorded in the absence of the auxiliary subunit Ostm1, differently to recent data obtained in Xenopus oocytes using a CLC-7 mutant with partial plasma membrane expression. We also show that plasma membrane-targeted CLC-7(E245A) is non-functional in Xenopus oocytes when expressed without Ostm1. In summary, our data suggest the existence of an alternative CLC-7 operating mode, which is active when the protein is not in complex with Ostm1. The vacuolar expression system has the potential to become a valuable tool for functional studies on intracellular ion channels and transporters from animal cells.
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Affiliation(s)
- Alex Costa
- University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy
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Scholz-Starke J, Cesca F, Schiavo G, Benfenati F, Baldelli P. Kidins220/ARMS is a novel modulator of short-term synaptic plasticity in hippocampal GABAergic neurons. PLoS One 2012; 7:e35785. [PMID: 22563401 PMCID: PMC3338529 DOI: 10.1371/journal.pone.0035785] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 03/21/2012] [Indexed: 01/09/2023] Open
Abstract
Kidins220 (Kinase D interacting substrate of 220 kDa)/ARMS (Ankyrin Repeat-rich Membrane Spanning) is a scaffold protein highly expressed in the nervous system. Previous work on neurons with altered Kidins220/ARMS expression suggested that this protein plays multiple roles in synaptic function. In this study, we analyzed the effects of Kidins220/ARMS ablation on basal synaptic transmission and on a variety of short-term plasticity paradigms in both excitatory and inhibitory synapses using a recently described Kidins220 full knockout mouse. Hippocampal neuronal cultures prepared from embryonic Kidins220−/− (KO) and wild type (WT) littermates were used for whole-cell patch-clamp recordings of spontaneous and evoked synaptic activity. Whereas glutamatergic AMPA receptor-mediated responses were not significantly affected in KO neurons, specific differences were detected in evoked GABAergic transmission. The recovery from synaptic depression of inhibitory post-synaptic currents in WT cells showed biphasic kinetics, both in response to paired-pulse and long-lasting train stimulation, while in KO cells the respective slow components were strongly reduced. We demonstrate that the slow recovery from synaptic depression in WT cells is caused by a transient reduction of the vesicle release probability, which is absent in KO neurons. These results suggest that Kidins220/ARMS is not essential for basal synaptic transmission and various forms of short-term plasticity, but instead plays a novel role in the mechanisms regulating the recovery of synaptic strength in GABAergic synapses.
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Affiliation(s)
- Joachim Scholz-Starke
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.
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Rocchetti A, Sharma T, Wulfetange C, Scholz-Starke J, Grippa A, Carpaneto A, Dreyer I, Vitale A, Czempinski K, Pedrazzini E. The putative K(+) channel subunit AtKCO3 forms stable dimers in Arabidopsis. Front Plant Sci 2012; 3:251. [PMID: 23162563 PMCID: PMC3495302 DOI: 10.3389/fpls.2012.00251] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 10/22/2012] [Indexed: 05/20/2023]
Abstract
The permeation pore of K(+) channels is formed by four copies of the pore domain. AtKCO3 is the only putative voltage-independent K(+) channel subunit of Arabidopsis thaliana with a single pore domain. KCO3-like proteins recently emerged in evolution and, to date, have been found only in the genus Arabidopsis (A. thaliana and A. lyrata). We show that the absence of KCO3 does not cause marked changes in growth under various conditions. Only under osmotic stress we observed reduced root growth of the kco3-1 null-allele line. This phenotype was complemented by expressing a KCO3 mutant with an inactive pore, indicating that the function of KCO3 under osmotic stress does not depend on its direct ability to transport ions. Constitutively overexpressed AtKCO3 or AtKCO3::GFP are efficiently sorted to the tonoplast indicating that the protein is approved by the endoplasmic reticulum quality control. However, vacuoles isolated from transgenic plants do not have significant alterations in current density. Consistently, both AtKCO3 and AtKCO3::GFP are detected as homodimers upon velocity gradient centrifugation, an assembly state that would not allow for activity. We conclude that if AtKCO3 ever functions as a K(+) channel, active tetramers are held by particularly weak interactions, are formed only in unknown specific conditions and may require partner proteins.
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Affiliation(s)
- Alessandra Rocchetti
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle RicercheMilano, Italy
- Alessandra Rocchetti and Tripti Sharma have contributed equally to the work
| | - Tripti Sharma
- Institute of Biochemistry and Biology, University of PotsdamPotsdam-Golm, Germany
- Alessandra Rocchetti and Tripti Sharma have contributed equally to the work
| | - Camilla Wulfetange
- Institute of Biochemistry and Biology, University of PotsdamPotsdam-Golm, Germany
| | | | - Alexandra Grippa
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle RicercheMilano, Italy
| | - Armando Carpaneto
- Istituto di Biofisica, Consiglio Nazionale delle RicercheGenova, Italy
| | - Ingo Dreyer
- Institute of Biochemistry and Biology, University of PotsdamPotsdam-Golm, Germany
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de MadridMadrid, Spain
| | - Alessandro Vitale
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle RicercheMilano, Italy
| | - Katrin Czempinski
- Institute of Biochemistry and Biology, University of PotsdamPotsdam-Golm, Germany
| | - Emanuela Pedrazzini
- Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle RicercheMilano, Italy
- *Correspondence: Emanuela Pedrazzini, Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, via Bassini 15, 20133 Milano, Italy. e-mail:
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Cesca F, Yabe A, Spencer-Dene B, Scholz-Starke J, Medrihan L, Maden CH, Gerhardt H, Orriss IR, Baldelli P, Al-Qatari M, Koltzenburg M, Adams RH, Benfenati F, Schiavo G. Kidins220/ARMS mediates the integration of the neurotrophin and VEGF pathways in the vascular and nervous systems. Cell Death Differ 2011; 19:194-208. [PMID: 22048155 DOI: 10.1038/cdd.2011.141] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Signaling downstream of receptor tyrosine kinases controls cell differentiation and survival. How signals from different receptors are integrated is, however, still poorly understood. In this work, we have identified Kidins220 (Kinase D interacting substrate of 220 kDa)/ARMS (Ankyrin repeat-rich membrane spanning) as a main player in the modulation of neurotrophin and vascular endothelial growth factor (VEGF) signaling in vivo, and a primary determinant for neuronal and cardiovascular development. Kidins220(-/-) embryos die at late stages of gestation, and show extensive cell death in the central and peripheral nervous systems. Primary neurons from Kidins220(-/-) mice exhibit reduced responsiveness to brain-derived neurotrophic factor, in terms of activation of mitogen-activated protein kinase signaling, neurite outgrowth and potentiation of excitatory postsynaptic currents. In addition, mice lacking Kidins220 display striking cardiovascular abnormalities, possibly due to impaired VEGF signaling. In support of this hypothesis, we demonstrate that Kidins220 constitutively interacts with VEGFR2. These findings, together with the data presented in the accompanying paper, indicate that Kidins220 mediates the integration of several growth factor receptor pathways during development, and mediates the activation of distinct downstream cascades according to the location and timing of stimulation.
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Affiliation(s)
- F Cesca
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, via Morego 30, 16163 Genoa, Italy.
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Meyer S, Scholz-Starke J, De Angeli A, Kovermann P, Burla B, Gambale F, Martinoia E. Malate transport by the vacuolar AtALMT6 channel in guard cells is subject to multiple regulation. Plant J 2011; 67:247-57. [PMID: 21443686 DOI: 10.1111/j.1365-313x.2011.04587.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Gas exchange in plants is controlled by guard cells, specialized cells acting as turgor pressure-driven valves. Malate is one of the major anions accumulated inside the vacuole during stomatal opening counteracting the positive charge of potassium. AtALMT6, a member of the aluminum-activated malate transporter family, is expressed in guard cells of leaves and stems as well as in flower organs of Arabidopsis thaliana. An AtALMT6-GFP fusion protein was targeted to the vacuolar membrane both in transient and stable expression systems. Patch-clamp experiments on vacuoles isolated from AtALMT6-GFP over-expressing Arabidopsis plants revealed large inward-rectifying malate currents only in the presence of micromolar cytosolic calcium concentrations. Further analyses showed that vacuolar pH and cytosolic malate regulate the threshold of activation of AtALMT6-mediated currents. The interplay of these two factors determines the AtALMT6 function as a malate influx or efflux channel depending on the tonoplast potential. Guard cell vacuoles isolated from Atalmt6 knock-out plants displayed reduced malate currents compared with wild-type vacuoles. This reduction, however, was not accompanied by phenotypic differences in the stomatal movements in knock-out plants, probably because of functional redundancy of malate transporters in guard cell vacuoles.
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Affiliation(s)
- Stefan Meyer
- Institute of Plant Biology, University of Zurich, Zurich, Switzerland
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Meyer S, Scholz-Starke J, De Angeli A, Kovermann P, Burla B, Gambale F, Martinoia E. Malate transport by the vacuolar AtALMT6 channel in guard cells is subject to multiple regulation. Plant J 2011. [PMID: 21443686 DOI: 10.1111/j.365-313x.2011.04587.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Gas exchange in plants is controlled by guard cells, specialized cells acting as turgor pressure-driven valves. Malate is one of the major anions accumulated inside the vacuole during stomatal opening counteracting the positive charge of potassium. AtALMT6, a member of the aluminum-activated malate transporter family, is expressed in guard cells of leaves and stems as well as in flower organs of Arabidopsis thaliana. An AtALMT6-GFP fusion protein was targeted to the vacuolar membrane both in transient and stable expression systems. Patch-clamp experiments on vacuoles isolated from AtALMT6-GFP over-expressing Arabidopsis plants revealed large inward-rectifying malate currents only in the presence of micromolar cytosolic calcium concentrations. Further analyses showed that vacuolar pH and cytosolic malate regulate the threshold of activation of AtALMT6-mediated currents. The interplay of these two factors determines the AtALMT6 function as a malate influx or efflux channel depending on the tonoplast potential. Guard cell vacuoles isolated from Atalmt6 knock-out plants displayed reduced malate currents compared with wild-type vacuoles. This reduction, however, was not accompanied by phenotypic differences in the stomatal movements in knock-out plants, probably because of functional redundancy of malate transporters in guard cell vacuoles.
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Affiliation(s)
- Stefan Meyer
- Institute of Plant Biology, University of Zurich, Zurich, Switzerland
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Gradogna A, Scholz-Starke J, Gutla PVK, Carpaneto A. Fluorescence combined with excised patch: measuring calcium currents in plant cation channels. Plant J 2009; 58:175-82. [PMID: 19067975 DOI: 10.1111/j.1365-313x.2008.03762.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Combined application of the patch-clamp technique and fura-2 fluorescence detection enables the study of study calcium fluxes or related increases in cytosolic calcium concentration. Here we used the excised patch configuration, focusing the photomultiplier on the tip of the recording pipette where the fluorescent dye was present (FLEP, fluorescence combined with excised patch). This configuration has several advantages, i.e. a lack of delay in loading the fluorophore, of interference by internal calcium buffers and of photobleaching, due to the quasi-infinite dye reservoir inside the pipette. Upon voltage stimulation of tonoplast patches, sustained and robust fluorescence signals indicated permeation of calcium through the slow vacuolar (SV) channel. Both SV currents and fluorescence signal changes were absent in the presence of SV channel inhibitors and in vacuoles from Arabidopsis tpc1 knockout plants that lack SV channel activity. The fractional calcium currents of this non-selective cation channel were voltage-dependent, and were approximately 10% of the total SV currents at elevated positive potentials. Interestingly, calcium permeation could be recorded as the same time as oppositely directed potassium fluxes. These events would have been impossible to detect using patch-clamp measurements alone. Thus, we propose use of the FLEP technique for the study of divalent ion-selective channels or transporters that may be difficult to access using conventional electrophysiological approaches.
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Affiliation(s)
- Antonella Gradogna
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Via de Marini 6, 16149 Genova, Italy
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Kovermann P, Meyer S, Hörtensteiner S, Picco C, Scholz-Starke J, Ravera S, Lee Y, Martinoia E. The Arabidopsis vacuolar malate channel is a member of the ALMT family. Plant J 2007; 52:1169-80. [PMID: 18005230 DOI: 10.1111/j.1365-313x.2007.03367.x] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In plants, malate is a central metabolite and fulfills a large number of functions. Vacuolar malate may reach very high concentrations and fluctuate rapidly, whereas cytosolic malate is kept at a constant level allowing optimal metabolism. Recently, a vacuolar malate transporter (Arabidopsis thaliana tonoplast dicarboxylate transporter, AttDT) was identified that did not correspond to the well-characterized vacuolar malate channel. We therefore hypothesized that a member of the aluminum-activated malate transporter (ALMT) gene family could code for a vacuolar malate channel. Using GFP fusion constructs, we could show that AtALMT9 (A. thaliana ALMT9) is targeted to the vacuole. Promoter-GUS fusion constructs demonstrated that this gene is expressed in all organs, but is cell-type specific as GUS activity in leaves was detected nearly exclusively in mesophyll cells. Patch-clamp analysis of an Atalmt9 T-DNA insertion mutant exhibited strongly reduced vacuolar malate channel activity. In order to functionally characterize AtALMT9 as a malate channel, we heterologously expressed this gene in tobacco and in oocytes. Overexpression of AtALMT9-GFP in Nicotiana benthamiana leaves strongly enhanced the malate current densities across the mesophyll tonoplasts. Functional expression of AtALMT9 in Xenopus oocytes induced anion currents, which were clearly distinguishable from endogenous oocyte currents. Our results demonstrate that AtALMT9 is a vacuolar malate channel. Deletion mutants for AtALMT9 exhibit only slightly reduced malate content in mesophyll protoplasts and no visible phenotype, indicating that AttDT and the residual malate channel activity are sufficient to sustain the transport activity necessary to regulate the cytosolic malate homeostasis.
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Affiliation(s)
- Peter Kovermann
- Institute for Plant Biology, University of Zürich, CH-8008 Zürich, Switzerland
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32
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Affiliation(s)
- Joachim Scholz-Starke
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Via De Marini 6, 16149 Genoa, Italy
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Abstract
This study investigates the interaction of the aminoglycoside antibiotic neomycin with the slow vacuolar (SV) channel in vacuoles from Arabidopsis thaliana mesophyll cells. Patch-clamp experiments in the excised patch configuration revealed a complex pattern of neomycin effects on the channel: applied at concentrations in the submicromolar to millimolar range neomycin (a) blocked macroscopic SV currents in a voltage- and concentration-dependent manner, (b) slowed down activation and deactivation kinetics of the channel, and most interestingly, (c) at concentrations above 10 μM, neomycin shifted the SV activation threshold towards negative membrane potentials, causing a two-phasic activation at high concentrations. Single channel experiments showed that neomycin causes these macroscopic effects by combining a decrease of the single channel conductance with a concomitant increase of the channel's open probability. Our results clearly demonstrate that the SV channel can be activated at physiologically relevant tonoplast potentials in the presence of an organic effector molecule. We therefore propose the existence of a cellular equivalent regulating the activity of the SV channel in vivo.
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Hoth S, Schneidereit A, Lauterbach C, Scholz-Starke J, Sauer N. Nematode infection triggers the de novo formation of unloading phloem that allows macromolecular trafficking of green fluorescent protein into syncytia. Plant Physiol 2005; 138:383-92. [PMID: 15849304 PMCID: PMC1104191 DOI: 10.1104/pp.104.058800] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 02/11/2005] [Accepted: 02/11/2005] [Indexed: 05/18/2023]
Abstract
Syncytial feeding complexes induced by the cyst nematode Heterodera schachtii represent strong metabolic sinks for photoassimilates. These newly formed structures were described to be symplastically isolated from the surrounding root tissue and their mechanism of carbohydrate import has repeatedly been under investigation. Here, we present analyses of the symplastic connectivity between the root phloem and these syncytia in nematode-infected Arabidopsis (Arabidopsis thaliana) plants expressing the gene of the green fluorescent protein (GFP) or of different GFP fusions under the control of the companion cell (CC)-specific AtSUC2 promoter. In the same plants, phloem differentiation during syncytium formation was monitored using cell-specific antibodies for CCs or sieve elements (SEs). Our results demonstrate that free, CC-derived GFP moved freely from the phloem into the syncytial domain. No or only marginal cell-to-cell passage of GFP was observed into other root cells adjacent to these syncytia. In contrast, membrane-anchored GFP variants as well as soluble GFP fusions with increased molecular masses were restricted to the SE-CC complex. The presented data also show that nematode infection triggers the de novo formation of phloem containing an approximately 3-fold excess of SEs over CCs. This newly formed phloem exhibits typical properties of unloading phloem previously described in other sink tissues. Our results reveal the existence of a symplastic pathway between phloem CCs and nematode-induced syncytia. The plasmodesmata responsible for this symplastic connectivity allow the cell-to-cell movement of macromolecules up to 30 kD and are likely to represent the major or exclusive path for the supply of assimilates from the phloem into the syncytial complex.
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Affiliation(s)
- Stefan Hoth
- Molekulare Pflanzenphysiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
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Schneidereit A, Scholz-Starke J, Sauer N, Büttner M. AtSTP11, a pollen tube-specific monosaccharide transporter in Arabidopsis. Planta 2005; 221:48-55. [PMID: 15565288 DOI: 10.1007/s00425-004-1420-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Accepted: 10/07/2004] [Indexed: 05/24/2023]
Abstract
Pollen development, as well as pollen germination and pollen tube growth, requires a highly regulated supply of sugars. In this paper we describe the molecular, kinetic, and physiological characterization of AtSTP11, a new member of the H+/monosaccharide transporter family in Arabidopsis thaliana (L.) Heynh. Heterologous expression in yeast (Saccharomyces cerevisiae) showed that AtSTP11 is a high-affinity (Km = 25 microM), broad-spectrum, and uncoupler-sensitive monosaccharide transporter of the plasma membrane. In reverse transcription-polymerase chain reaction analyses we found that AtSTP11 expression is restricted to flowers. Furthermore, AtSTP11-promoter::GFP plants revealed that AtSTP11 expression is only found in pollen tubes. Using a specific antibody we could also detect the AtSTP11 protein exclusively in pollen tubes but not in other flower tissues or in pollen grains of any developmental stage. These results suggest that the newly identified AtSTP11 transporter plays a role in the supply of monosaccharides to growing pollen tubes.
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Affiliation(s)
- Alexander Schneidereit
- Molekulare Pflanzenphysiologie, Universität Erlangen-Nürnberg, Staudtstrasse 5, 91058 Erlangen, Germany
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Scholz-Starke J, Gambale F, Carpaneto A. Modulation of plant ion channels by oxidizing and reducing agents. Arch Biochem Biophys 2005; 434:43-50. [PMID: 15629107 DOI: 10.1016/j.abb.2004.06.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2004] [Revised: 06/11/2004] [Indexed: 12/19/2022]
Abstract
Ion channels are proteins forming hydrophilic pathways through the membranes of all living organisms. They play important roles in the electrogenic transport of ions and metabolites. Because of biophysical properties such as high selectivity for the permeant ion, high turnover rate, and modulation by physico-chemical parameters (e.g., membrane potential, calcium concentration), they are involved in several physiological processes in plant cells (e.g., maintenance of the turgor pressure, stomatal movements, and nutrient absorption by the roots). As plants cannot move, plant metabolism must be flexible and dynamic, to cope with environmental changes, to compete with other living species and to prevent pathogen invasion. An example of this flexibility and dynamic behavior is represented by their handling of the so-called reactive oxygen species, inevitable by-products of aerobic metabolism. Plants cope with these species on one side avoiding their toxic effects, on the other utilizing them as signalling molecules and as a means of defence against pathogens. In this review, we present the state-of-the-art of the modulation of plant ion channels by oxidizing and reducing agents.
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Affiliation(s)
- J Scholz-Starke
- Istituto di Biofisica, Genova, C.N.R., Via De Marini 6, 16149 Genova, Italy
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Scholz-Starke J, De Angeli A, Ferraretto C, Paluzzi S, Gambale F, Carpaneto A. Redox-dependent modulation of the carrot SV channel by cytosolic pH. FEBS Lett 2004; 576:449-54. [PMID: 15498579 DOI: 10.1016/j.febslet.2004.09.052] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Revised: 09/14/2004] [Accepted: 09/24/2004] [Indexed: 11/30/2022]
Abstract
Currents mediated by a slow vacuolar (SV) channel were recorded and characterized in vacuoles from cultured carrot cells. The carrot channel shows the typical functional characteristics reported for channels of the SV category previously identified in other plants, i.e., slow voltage-dependent activation kinetics, current activation favoured by cytosolic calcium and permeability to different monovalent cations. The carrot channel is strongly activated by cytosolic reducing agents (such as dithiothreitol, DTT, and glutathione, GSH) and has a peculiar dependence on cytosolic pH, which, in turn, is affected by the concentration of cytosolic reducing agents. Specifically, in 1 mM DTT or GSH the channel displayed a maximum conductance at neutral pH. The normalized conductance did not depend significantly on DTT concentration at acidic pH, while at alkaline pH the attenuation of the normalized conductance declines with increasing DTT concentration. Our results suggest two pH-titratable groups within the carrot SV channel, one of these depending on cysteine residues exposed to the cytosolic side of the vacuole.
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Affiliation(s)
- Joachim Scholz-Starke
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Via De Marini 6, 16149 Genova, Italy.
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38
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Schneidereit A, Scholz-Starke J, Büttner M. Functional characterization and expression analyses of the glucose-specific AtSTP9 monosaccharide transporter in pollen of Arabidopsis. Plant Physiol 2003; 133:182-90. [PMID: 12970485 PMCID: PMC196596 DOI: 10.1104/pp.103.026674] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2003] [Revised: 06/10/2003] [Accepted: 06/17/2003] [Indexed: 05/18/2023]
Abstract
A genomic clone and the corresponding cDNA of a new Arabidopsis monosaccharide transporter AtSTP9 were isolated. Transport analysis of the expressed protein in yeast showed that AtSTP9 is an energy-dependent, uncoupler-sensitive, high-affinity monosaccharide transporter with a K(m) for glucose in the micromolar range. In contrast to all previously characterized monosaccharide transporters, AtSTP9 shows an unusual specificity for glucose. Reverse transcriptase-polymerase chain reaction analyses revealed that AtSTP9 is exclusively expressed in flowers, and a more detailed approach using AtSTP9 promoter/reporter plants clearly showed that AtSTP9 expression is restricted to the male gametophyte. AtSTP9 expression is not found in other floral organs or vegetative tissues. Further localization on the cellular level using a specific antibody revealed that in contrast to the early accumulation of AtSTP9 transcripts in young pollen, the AtSTP9 protein is only found weakly in mature pollen but is most prominent in germinating pollen tubes. This preloading of pollen with mRNAs has been described for genes that are essential for pollen germination and/or pollen tube growth. The pollen-specific expression found for AtSTP9 is also observed for other sugar transporters and indicates that pollen development and germination require a highly regulated supply of sugars.
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MESH Headings
- Amino Acid Sequence
- Arabidopsis/genetics
- Arabidopsis/growth & development
- Arabidopsis/metabolism
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Cloning, Molecular
- DNA, Bacterial/genetics
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Plant
- Genes, Reporter/genetics
- Genes, Reporter/physiology
- Glucose/metabolism
- Molecular Sequence Data
- Monosaccharide Transport Proteins/genetics
- Monosaccharide Transport Proteins/metabolism
- Mutagenesis, Insertional
- Mutation
- Pollen/genetics
- Pollen/growth & development
- Pollen/metabolism
- Promoter Regions, Genetic/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
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Affiliation(s)
- Alexander Schneidereit
- Molekulare Pflanzenphysiologie, Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen, Germany
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39
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Juergensen K, Scholz-Starke J, Sauer N, Hess P, van Bel AJE, Grundler FMW. The companion cell-specific Arabidopsis disaccharide carrier AtSUC2 is expressed in nematode-induced syncytia. Plant Physiol 2003; 131:61-9. [PMID: 12529515 PMCID: PMC166787 DOI: 10.1104/pp.008037] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2002] [Revised: 06/19/2002] [Accepted: 08/25/2002] [Indexed: 05/18/2023]
Abstract
Cyst nematodes induce a metabolically highly active syncytial cell complex in host roots. The syncytia are symplastically isolated. Because they form a strong sink, assimilates must be imported via the apoplast, thus suggesting that specific membrane-bound sugar transport proteins are expressed and activated. To identify possible candidate genes, transgenic Arabidopsis plants expressing different reporter genes under the control of different promoters from Arabidopsis sugar transporter genes were infected with the beet cyst nematode (Heterodera schachtii). With polymerase chain reaction, 13 additional sugar transporters were tested for their presence in the syncytia through the use of a syncytium-specific cDNA library. Analysis of the infected roots showed that the promoter of the sucrose (Suc) transporter AtSUC2 gene that codes for a companion cell-specific Suc transporter in noninfected plants was found to be expressed in syncytia. Its expression patterns in beta-glucuronidase and green fluorescent protein plants were monitored. Syncytium-specific gene expression was confirmed by reverse transcriptase-polymerase chain reaction. Results support the idea that AtSUC2 mediates the transmembrane transfer of Suc. AtSUC2 is the first disaccharide carrier described to be activated by pathogens.
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Affiliation(s)
- Katja Juergensen
- Institut für Phytopathologie, Christian-Albrechts-Universität Kiel, Hermann-Rodewald-Strasse 9, D-24098 Kiel, Germany
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Scholz-Starke J, Büttner M, Sauer N. AtSTP6, a new pollen-specific H+-monosaccharide symporter from Arabidopsis. Plant Physiol 2003; 131:70-7. [PMID: 12529516 PMCID: PMC166788 DOI: 10.1104/pp.012666] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2002] [Revised: 09/23/2002] [Accepted: 09/29/2002] [Indexed: 05/19/2023]
Abstract
This paper describes the molecular, kinetic, and physiological characterization of AtSTP6, a new member of the Arabidopsis H(+)/monosaccharide transporter family. The AtSTP6 gene (At3g05960) is interrupted by two introns and encodes a protein of 507 amino acids containing 12 putative transmembrane helices. Expression in yeast (Saccharomyces cerevisiae) shows that AtSTP6 is a high-affinity (K(m) = 20 microM), broad-spectrum, and uncoupler-sensitive monosaccharide transporter that is targeted to the plasma membrane and that can complement a growth deficiency resulting from the disruption of most yeast hexose transporter genes. Analyses of AtSTP6-promoter::GUS plants and in situ hybridization experiments detected AtSTP6 expression only during the late stages of pollen development. A transposon-tagged Arabidopsis mutant was isolated and homozygous plants were analyzed for potential effects of the Atstp6 mutation on pollen viability, pollen germination, fertilization, and seed production. However, differences between wild-type and mutant plants could not be observed.
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Affiliation(s)
- Joachim Scholz-Starke
- Molekulare Pflanzenphysiologie, Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen, Germany
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