1
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Bavnhøj L, Driller JH, Zuzic L, Stange AD, Schiøtt B, Pedersen BP. Structure and sucrose binding mechanism of the plant SUC1 sucrose transporter. NATURE PLANTS 2023; 9:938-950. [PMID: 37188854 PMCID: PMC10281868 DOI: 10.1038/s41477-023-01421-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 04/19/2023] [Indexed: 05/17/2023]
Abstract
Sucrose import from photosynthetic tissues into the phloem is mediated by transporters from the low-affinity sucrose transporter family (SUC/SUT family). Furthermore, sucrose redistribution to other tissues is driven by phloem sap movement, the product of high turgor pressure created by this import activity. Additionally, sink organs such as fruits, cereals and seeds that accumulate high concentrations of sugar also depend on this active transport of sucrose. Here we present the structure of the sucrose-proton symporter, Arabidopsis thaliana SUC1, in an outward open conformation at 2.7 Å resolution, together with molecular dynamics simulations and biochemical characterization. We identify the key acidic residue required for proton-driven sucrose uptake and describe how protonation and sucrose binding are strongly coupled. Sucrose binding is a two-step process, with initial recognition mediated by the glucosyl moiety binding directly to the key acidic residue in a stringent pH-dependent manner. Our results explain how low-affinity sucrose transport is achieved in plants, and pinpoint a range of SUC binders that help define selectivity. Our data demonstrate a new mode for proton-driven symport with links to cation-driven symport and provide a broad model for general low-affinity transport in highly enriched substrate environments.
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Affiliation(s)
- Laust Bavnhøj
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Jan Heiner Driller
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Lorena Zuzic
- Department of Chemistry, Aarhus University, Aarhus, Denmark
| | | | - Birgit Schiøtt
- Department of Chemistry, Aarhus University, Aarhus, Denmark
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2
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Sanchez-Arcos C, Paris D, Mazzella V, Mutalipassi M, Costantini M, Buia MC, von Elert E, Cutignano A, Zupo V. Responses of the Macroalga Ulva prolifera Müller to Ocean Acidification Revealed by Complementary NMR- and MS-Based Omics Approaches. Mar Drugs 2022; 20:md20120743. [PMID: 36547890 PMCID: PMC9783899 DOI: 10.3390/md20120743] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
Ocean acidification (OA) is a dramatic perturbation of seawater environments due to increasing anthropogenic emissions of CO2. Several studies indicated that OA frequently induces marine biota stress and a reduction of biodiversity. Here, we adopted the macroalga Ulva prolifera as a model and applied a complementary multi-omics approach to investigate the metabolic profiles under normal and acidified conditions. Our results show that U. prolifera grows at higher rates in acidified environments. Consistently, we observed lower sucrose and phosphocreatine concentrations in response to a higher demand of energy for growth and a higher availability of essential amino acids, likely related to increased protein biosynthesis. In addition, pathways leading to signaling and deterrent compounds appeared perturbed. Finally, a remarkable shift was observed here for the first time in the fatty acid composition of triglycerides, with a decrease in the relative abundance of PUFAs towards an appreciable increase of palmitic acid, thus suggesting a remodeling in lipid biosynthesis. Overall, our studies revealed modulation of several biosynthetic pathways under OA conditions in which, besides the possible effects on the marine ecosystem, the metabolic changes of the alga should be taken into account considering its potential nutraceutical applications.
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Affiliation(s)
- Carlos Sanchez-Arcos
- Institute for Zoology, Cologne Biocenter University of Cologne, 50674 Köln, Germany
| | - Debora Paris
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Chimica Biomolecolare (ICB), 80078 Pozzuoli, Italy
| | - Valerio Mazzella
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Ischia Marine Center, 80077 Ischia, Italy
| | - Mirko Mutalipassi
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Calabria Marine Centre, 87071 Amendolara, Italy
| | - Maria Costantini
- Department of Ecosustainable Marine Biotechnology, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
| | - Maria Cristina Buia
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Ischia Marine Center, 80077 Ischia, Italy
| | - Eric von Elert
- Institute for Zoology, Cologne Biocenter University of Cologne, 50674 Köln, Germany
| | - Adele Cutignano
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Chimica Biomolecolare (ICB), 80078 Pozzuoli, Italy
- Department of Ecosustainable Marine Biotechnology, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
- Correspondence: (A.C.); (V.Z.); Tel.: +39-081-8675313 (A.C.); +39-081-5833503 (V.Z.)
| | - Valerio Zupo
- Department of Ecosustainable Marine Biotechnology, Stazione Zoologica Anton Dohrn, 80077 Ischia, Italy
- Correspondence: (A.C.); (V.Z.); Tel.: +39-081-8675313 (A.C.); +39-081-5833503 (V.Z.)
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3
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Rottmann TM, Fritz C, Lauter A, Schneider S, Fischer C, Danzberger N, Dietrich P, Sauer N, Stadler R. Protoplast-Esculin Assay as a New Method to Assay Plant Sucrose Transporters: Characterization of AtSUC6 and AtSUC7 Sucrose Uptake Activity in Arabidopsis Col-0 Ecotype. FRONTIERS IN PLANT SCIENCE 2018; 9:430. [PMID: 29740457 PMCID: PMC5925572 DOI: 10.3389/fpls.2018.00430] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/20/2018] [Indexed: 05/20/2023]
Abstract
The best characterized function of sucrose transporters of the SUC family in plants is the uptake of sucrose into the phloem for long-distance transport of photoassimilates. This important step is usually performed by one specific SUC in every species. However, plants possess small families of several different SUCs which are less well understood. Here, we report on the characterization of AtSUC6 and AtSUC7, two members of the SUC family in Arabidopsis thaliana. Heterologous expression in yeast (Saccharomyces cerevisiae) revealed that AtSUC6Col-0 is a high-affinity H+-symporter that mediates the uptake of sucrose and maltose across the plasma membrane at exceptionally low pH values. Reporter gene analyses revealed a strong expression of AtSUC6Col-0 in reproductive tissues, where the protein product might contribute to sugar uptake into pollen tubes and synergid cells. A knockout of AtSUC6 did not interfere with vegetative development or reproduction, which points toward physiological redundancy of AtSUC6Col-0 with other sugar transporters. Reporter gene analyses showed that AtSUC7Col-0 is expressed in roots and pollen tubes and that this sink specific expression of AtSUC7Col-0 is regulated by intragenic regions. Transport activity of AtSUC7Col-0 could not be analyzed in baker's yeast or Xenopus oocytes because the protein was not correctly targeted to the plasma membrane in both heterologous expression systems. Therefore, a novel approach to analyze sucrose transporters in planta was developed. Plasma membrane localized SUCs including AtSUC6Col-0 and also sucrose specific SWEETs were able to mediate transport of the fluorescent sucrose analog esculin in transformed mesophyll protoplasts. In contrast, AtSUC7Col-0 is not able to mediate esculin transport across the plasma membrane which implicates that AtSUC7Col-0 might be a non-functional pseudogene. The novel protoplast assay provides a useful tool for the quick and quantitative analysis of sucrose transporters in an in planta expression system.
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4
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Yamada K, Osakabe Y. Sugar compartmentation as an environmental stress adaptation strategy in plants. Semin Cell Dev Biol 2017; 83:106-114. [PMID: 29287835 DOI: 10.1016/j.semcdb.2017.12.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 12/15/2017] [Accepted: 12/21/2017] [Indexed: 10/18/2022]
Abstract
The sessile nature of plants has driven their evolution to cope flexibly with ever-changing surrounding environments. The development of stress tolerance traits is complex, and a broad range of cellular processes are involved. Recent studies have revealed that sugar transporters contribute to environmental stress tolerance in plants, suggesting that sugar flow is dynamically fluctuated towards optimization of cellular conditions in adverse environments. Here, we highlight sugar compartmentation mediated by sugar transporters as an adaptation strategy against biotic and abiotic stresses. Competition for sugars between host plants and pathogens shapes their evolutionary arms race. Pathogens, which rely on host-derived carbon, manipulate plant sugar transporters to access sugars easily, while plants sequester sugars from pathogens by enhancing sugar uptake activity. Furthermore, we discuss pathogen tactics to circumvent sugar competition with host plants. Sugar transporters also play a role in abiotic stress tolerance. Exposure to abiotic stresses such as cold or drought stress induces sugar accumulation in various plants. We also discuss how plants allocate sugars under such conditions. Collectively, these findings are relevant to basic plant biology as well as potential applications in agriculture, and provide opportunities to improve crop yield for a growing population.
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Affiliation(s)
- Kohji Yamada
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Japan; PRESTO, Japan Science and Technology Agency, Japan.
| | - Yuriko Osakabe
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Japan.
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5
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Wittek A, Dreyer I, Al-Rasheid KAS, Sauer N, Hedrich R, Geiger D. The fungal UmSrt1 and maize ZmSUT1 sucrose transporters battle for plant sugar resources. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2017; 59:422-435. [PMID: 28296205 DOI: 10.1111/jipb.12535] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 03/10/2017] [Indexed: 06/06/2023]
Abstract
The biotrophic fungus Ustilago maydis causes corn smut disease, inducing tumor formation in its host Zea mays. Upon infection, the fungal hyphae invaginate the plasma membrane of infected maize cells, establishing an interface where pathogen and host are separated only by their plasma membranes. At this interface the fungal and maize sucrose transporters, UmSrt1 and ZmSUT1, compete for extracellular sucrose in the corn smut/maize pathosystem. Here we biophysically characterized ZmSUT1 and UmSrt1 in Xenopus oocytes with respect to their voltage-, pH- and substrate-dependence and determined affinities toward protons and sucrose. In contrast to ZmSUT1, UmSrt1 has a high affinity for sucrose and is relatively pH- and voltage-independent. Using these quantitative parameters, we developed a mathematical model to simulate the competition for extracellular sucrose at the contact zone between the fungus and the host plant. This approach revealed that UmSrt1 exploits the apoplastic sucrose resource, which forces the plant transporter into a sucrose export mode providing the fungus with sugar from the phloem. Importantly, the high sucrose concentration in the phloem appeared disadvantageous for the ZmSUT1, preventing sucrose recovery from the apoplastic space in the fungus/plant interface.
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Affiliation(s)
- Anke Wittek
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, Biocenter, University of Würzburg, 97082 Würzburg, Germany
| | - Ingo Dreyer
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | | | - Norbert Sauer
- Molecular Plant Physiology, University Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, Biocenter, University of Würzburg, 97082 Würzburg, Germany
| | - Dietmar Geiger
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, Biocenter, University of Würzburg, 97082 Würzburg, Germany
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6
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Secchi F, Pagliarani C, Zwieniecki MA. The functional role of xylem parenchyma cells and aquaporins during recovery from severe water stress. PLANT, CELL & ENVIRONMENT 2017; 40:858-871. [PMID: 27628165 DOI: 10.1111/pce.12831] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/09/2016] [Accepted: 08/27/2016] [Indexed: 05/05/2023]
Abstract
Xylem parenchyma cells [vessel associated cells (VACs)] constitute a significant fraction of the xylem in woody plants. These cells are often closely connected with xylem vessels or tracheids via simple pores (remnants of plasmodesmata fields). The close contact and biological activity of VACs during times of severe water stress and recovery from stress suggest that they are involved in the maintenance of xylem transport capacity and responsible for the restoration of vessel/tracheid functionality following embolism events. As recovery from embolism requires the transport of water across xylem parenchyma cell membranes, an understanding of stem-specific aquaporin expression patterns, localization and activity is a crucial part of any biological model dealing with embolism recovery processes in woody plants. In this review, we provide a short overview of xylem parenchyma cell biology with a special focus on aquaporins. In particular we address their distributions and activity during the development of drought stress, during the formation of embolism and the subsequent recovery from stress that may result in refilling. Complemented by the current biological model of parenchyma cell function during recovery from stress, this overview highlights recent breakthroughs on the unique ability of long-lived perennial plants to undergo cycles of embolism-recovery related to drought/rewetting or freeze/thaw events.
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Affiliation(s)
- Francesca Secchi
- Department of Agricultural, Forest and Food Sciences (DISAFA), University of Turin, Grugliasco, 10095, Italy
| | - Chiara Pagliarani
- Department of Agricultural, Forest and Food Sciences (DISAFA), University of Turin, Grugliasco, 10095, Italy
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7
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Secchi F, Zwieniecki MA. Accumulation of sugars in the xylem apoplast observed under water stress conditions is controlled by xylem pH. PLANT, CELL & ENVIRONMENT 2016; 39:2350-2360. [PMID: 27187245 DOI: 10.1111/pce.12767] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 05/05/2016] [Accepted: 05/09/2016] [Indexed: 05/25/2023]
Abstract
Severe water stress constrains, or even stops, water transport in the xylem due to embolism formation. Previously, the xylem of poplar trees was shown to respond to embolism formation by accumulating carbohydrates in the xylem apoplast and dropping xylem sap pH. We hypothesize that these two processes may be functionally linked as lower pH activates acidic invertases degrading sucrose and inducing accumulation of monosaccharides in xylem apoplast. Using a novel in vivo method to measure xylem apoplast pH, we show that pH drops from ~6.2 to ~5.6 in stems of severely stressed plants and rises following recovery of stem water status. We also show that in a lower pH environment, sugars are continuously accumulating in the xylem apoplast. Apoplastic carbohydrate accumulation was reduced significantly in the presence of a proton pump blocker (orthovanadate). These observations suggest that a balance in sugar concentrations exists between the xylem apoplast and symplast that can be controlled by xylem pH and sugar concentration. We conclude that lower pH is related to loss of xylem transport function, eventually resulting in accumulation of sugars that primes stems for recovery from embolism when water stress is relieved.
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Affiliation(s)
- Francesca Secchi
- Department of Agricultural, Forest and Food Sciences (DISAFA), University of Torino, Italy.
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8
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Vatsa-Portugal P, Walker AS, Jacquens L, Clément C, Barka EA, Vaillant-Gaveau N. Inflorescences vs leaves: a distinct modulation of carbon metabolism process during Botrytis infection. PHYSIOLOGIA PLANTARUM 2015; 154:162-177. [PMID: 25251162 DOI: 10.1111/ppl.12287] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 07/30/2014] [Accepted: 08/21/2014] [Indexed: 06/03/2023]
Abstract
Plant growth and survival depends critically on photo assimilates. Pathogen infection leads to changes in carbohydrate metabolism of plants. In this study, we monitored changes in the carbohydrate metabolism in the grapevine inflorescence and leaves using Botrytis cinerea and Botrytis pseudo cinerea. Fluctuations in gas exchange were correlated with variations in chlorophyll a fluorescence. During infection, the inflorescences showed an increase in net photosynthesis (Pn) with a stomatal limitation. In leaves, photosynthesis decreased, with a non-stomatal limitation. A decrease in the effective photosystem II (PSII) quantum yield (ΦPSII) was accompanied by an increase in photochemical quenching (qP) and non-photochemical quenching (qN). The enhancement of qP and ΦPSII could explain the observed increase in Pn. In leaves, the significant decline in ΦPSII and qP, and increase in qN suggest that energy was mostly oriented toward heat dissipation instead of CO2 fixation. The accumulation of glucose and sucrose in inflorescences and glucose and fructose in the leaves during infection indicate that the plant's carbon metabolism is differently regulated in these two organs. While a strong accumulation of starch was observed at 24 and 48 hours post-inoculation (hpi) with both species of Botrytis in the inflorescences, a significant decrease with B. cinerea at 24 hpi and a significant increase with B. pseudo cinerea at 48 hpi were observed in the leaves. On the basis of these results, it can be said that during pathogen attack, the metabolism of grapevine inflorescence and leaf is modified suggesting distinct mechanisms modifying gas exchange, PSII activity and sugar contents in these two organs.
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Affiliation(s)
- Parul Vatsa-Portugal
- Laboratoire de Stress, Défenses et Reproduction des Plantes, Unité de Recherche Vigne et Vin de Champagne URVVC EA 4707, Université de Reims Champagne-Ardenne, UFR Sciences Exactes et Naturelles, Reims, F-51687, France
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9
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Hu Y, Fernández V, Ma L. Nitrate transporters in leaves and their potential roles in foliar uptake of nitrogen dioxide. FRONTIERS IN PLANT SCIENCE 2014; 5:360. [PMID: 25126090 PMCID: PMC4115617 DOI: 10.3389/fpls.2014.00360] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 07/04/2014] [Indexed: 05/07/2023]
Abstract
While plant roots are specialized organs for the uptake and transport of water and nutrients, the absorption of gaseous or liquid mineral elements by aerial plant parts has been recognized since more than one century. Nitrogen (N) is an essential macronutrient which generally absorbed either as nitrate (NO(-) 3) or ammonium (NH(+) 4) by plant roots. Gaseous nitrogen pollutants like N dioxide (NO2) can also be absorbed by plant surfaces and assimilated via the NO(-) 3 assimilation pathway. The subsequent NO(-) 3 flux may induce or repress the expression of various NO(-) 3-responsive genes encoding for instance, the transmembrane transporters, NO(-) 3/NO(-) 2 (nitrite) reductase, or assimilatory enzymes involved in N metabolism. Based on the existing information, the aim of this review was to theoretically analyze the potential link between foliar NO2 absorption and N transport and metabolism. For such purpose, an overview of the state of knowledge on the NO(-) 3 transporter genes identified in leaves or shoots of various species and their roles for NO(-) 3 transport across the tonoplast and plasma membrane, in addition to the process of phloem loading is briefly provided. It is assumed that a NO2-induced accumulation of NO(-) 3/NO(-) 2 may alter the expression of such genes, hence linking transmembrane NO(-) 3 transporters and foliar uptake of NO2. It is likely that NRT1/NRT2 gene expression and species-dependent apoplastic buffer capacity may be also related to the species-specific foliar NO2 uptake process. It is concluded that further work focusing on the expression of NRT1 (NRT1.1, NRT1.7, NRT1.11, and NRT1.12), NRT2 (NRT2.1, NRT2.4, and NRT2.5) and chloride channel family genes (CLCa and CLCd) may help us elucidate the physiological and metabolic response of plants fumigated with NO2.
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Affiliation(s)
- Yanbo Hu
- College of Life Science, Northeast Forestry UniversityHarbin, China
| | - Victoria Fernández
- Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of MadridMadrid, Spain
| | - Ling Ma
- School of Forestry, Northeast Forestry UniversityHarbin, China
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10
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Site directed mutagenesis of StSUT1 reveals target amino acids of regulation and stability. Biochimie 2013; 95:2132-44. [PMID: 23954800 DOI: 10.1016/j.biochi.2013.07.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 07/25/2013] [Indexed: 12/15/2022]
Abstract
Plant sucrose transporters (SUTs) are functional as sucrose-proton-cotransporters with an optimal transport activity in the acidic pH range. Recently, the pH optimum of the Solanum tuberosum sucrose transporter StSUT1 was experimentally determined to range at an unexpectedly low pH of 3 or even below. Various research groups have confirmed these surprising findings independently and in different organisms. Here we provide further experimental evidence for a pH optimum at physiological extrema. Site directed mutagenesis provides information about functional amino acids, which are highly conserved and responsible for this extraordinary increase in transport capacity under extreme pH conditions. Redox-dependent dimerization of the StSUT1 protein was described earlier. Here the ability of StSUT1 to form homodimers was demonstrated by heterologous expression in Lactococcus lactis and Xenopus leavis using Western blots, and in plants by bimolecular fluorescence complementation. Mutagenesis of highly conserved cysteine residues revealed their importance in protein stability. The accessibility of regulatory amino acid residues in the light of StSUT1's compartmentalization in membrane microdomains is discussed.
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11
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Derrer C, Wittek A, Bamberg E, Carpaneto A, Dreyer I, Geiger D. Conformational changes represent the rate-limiting step in the transport cycle of maize sucrose transporter1. THE PLANT CELL 2013; 25:3010-21. [PMID: 23964025 PMCID: PMC3784595 DOI: 10.1105/tpc.113.113621] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Proton-driven Suc transporters allow phloem cells of higher plants to accumulate Suc to more than 1 M, which is up to ~1000-fold higher than in the surrounding extracellular space. The carrier protein can accomplish this task only because proton and Suc transport are tightly coupled. This study provides insights into this coupling by resolving the first step in the transport cycle of the Suc transporter SUT1 from maize (Zea mays). Voltage clamp fluorometry measurements combining electrophysiological techniques with fluorescence-based methods enable the visualization of conformational changes of SUT1 expressed in Xenopus laevis oocytes. Using the Suc derivate sucralose, binding of which hinders conformational changes of SUT1, the association of protons to the carrier could be dissected from transport-associated movements of the protein. These combined approaches enabled us to resolve the binding of protons to the carrier and its interrelationship with the alternating movement of the protein. The data indicate that the rate-limiting step of the reaction cycle is determined by the accessibility of the proton binding site. This, in turn, is determined by the conformational change of the SUT1 protein, alternately exposing the binding pockets to the inward and to the outward face of the membrane.
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Affiliation(s)
- Carmen Derrer
- Julius-von-Sachs-Institute, Molecular Plant Physiology and Biophysics, University Würzburg, D-97082 Wuerzburg, Germany
| | - Anke Wittek
- Julius-von-Sachs-Institute, Molecular Plant Physiology and Biophysics, University Würzburg, D-97082 Wuerzburg, Germany
| | - Ernst Bamberg
- Max-Plant-Institute for Biophysics, Department of Biophysical Chemistry, D-60438 Frankfurt/Main, Germany
| | - Armando Carpaneto
- Instituto di Biofisica–Consiglio Nazionale delle Richerche, I-16149 Genova, Italy
| | - Ingo Dreyer
- Centre for Plant Biotechnology and Genomics, Universidad Politécnica de Madrid, Campus de Montegancedo, E-28223 Pozuelo de Alarcón (Madrid), Spain
| | - Dietmar Geiger
- Julius-von-Sachs-Institute, Molecular Plant Physiology and Biophysics, University Würzburg, D-97082 Wuerzburg, Germany
- Address correspondence to
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12
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Lemoine R, Camera SL, Atanassova R, Dédaldéchamp F, Allario T, Pourtau N, Bonnemain JL, Laloi M, Coutos-Thévenot P, Maurousset L, Faucher M, Girousse C, Lemonnier P, Parrilla J, Durand M. Source-to-sink transport of sugar and regulation by environmental factors. FRONTIERS IN PLANT SCIENCE 2013; 4:272. [PMID: 23898339 PMCID: PMC3721551 DOI: 10.3389/fpls.2013.00272] [Citation(s) in RCA: 539] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 07/02/2013] [Indexed: 05/18/2023]
Abstract
Source-to-sink transport of sugar is one of the major determinants of plant growth and relies on the efficient and controlled distribution of sucrose (and some other sugars such as raffinose and polyols) across plant organs through the phloem. However, sugar transport through the phloem can be affected by many environmental factors that alter source/sink relationships. In this paper, we summarize current knowledge about the phloem transport mechanisms and review the effects of several abiotic (water and salt stress, mineral deficiency, CO2, light, temperature, air, and soil pollutants) and biotic (mutualistic and pathogenic microbes, viruses, aphids, and parasitic plants) factors. Concerning abiotic constraints, alteration of the distribution of sugar among sinks is often reported, with some sinks as roots favored in case of mineral deficiency. Many of these constraints impair the transport function of the phloem but the exact mechanisms are far from being completely known. Phloem integrity can be disrupted (e.g., by callose deposition) and under certain conditions, phloem transport is affected, earlier than photosynthesis. Photosynthesis inhibition could result from the increase in sugar concentration due to phloem transport decrease. Biotic interactions (aphids, fungi, viruses…) also affect crop plant productivity. Recent breakthroughs have identified some of the sugar transporters involved in these interactions on the host and pathogen sides. The different data are discussed in relation to the phloem transport pathways. When possible, the link with current knowledge on the pathways at the molecular level will be highlighted.
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Affiliation(s)
- Remi Lemoine
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Sylvain La Camera
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Rossitza Atanassova
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Fabienne Dédaldéchamp
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Thierry Allario
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Nathalie Pourtau
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Jean-Louis Bonnemain
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Maryse Laloi
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Pierre Coutos-Thévenot
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Laurence Maurousset
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Mireille Faucher
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Christine Girousse
- Diversité et Ecophysiologie des Céréales, Unités Mixtes de RechercheClermont Ferrand, France
| | - Pauline Lemonnier
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Jonathan Parrilla
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
| | - Mickael Durand
- Unités Mixtes de Recherche, Ecologie et Biologie des Interactions, Université of Poitiers/Centre National de la Recherche ScientifiquePoitiers, France
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Doidy J, Grace E, Kühn C, Simon-Plas F, Casieri L, Wipf D. Sugar transporters in plants and in their interactions with fungi. TRENDS IN PLANT SCIENCE 2012; 17:413-22. [PMID: 22513109 DOI: 10.1016/j.tplants.2012.03.009] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 03/06/2012] [Accepted: 03/17/2012] [Indexed: 05/18/2023]
Abstract
Sucrose and monosaccharide transporters mediate long distance transport of sugar from source to sink organs and constitute key components for carbon partitioning at the whole plant level and in interactions with fungi. Even if numerous families of plant sugar transporters are defined; efflux capacities, subcellular localization and association to membrane rafts have only been recently reported. On the fungal side, the investigation of sugar transport mechanisms in mutualistic and pathogenic interactions is now emerging. Here, we review the essential role of sugar transporters for distribution of carbohydrates inside plant cells, as well as for plant-fungal interaction functioning. Altogether these data highlight the need for a better comprehension of the mechanisms underlying sugar exchanges between fungi and their host plants.
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Affiliation(s)
- Joan Doidy
- UMR INRA 1347, Agrosup, Université de Bourgogne, Agroécologie, Pôle Interactions Plantes Microorganismes ERL CNRS 6300, BP 86510, 21065 Dijon Cedex, France
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14
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Wippel K, Sauer N. Arabidopsis SUC1 loads the phloem in suc2 mutants when expressed from the SUC2 promoter. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:669-79. [PMID: 22021573 PMCID: PMC3254675 DOI: 10.1093/jxb/err255] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 07/18/2011] [Accepted: 07/27/2011] [Indexed: 05/18/2023]
Abstract
Active loading of sucrose into phloem companion cells (CCs) is an essential process in apoplastic loaders, such as Arabidopsis or tobacco (Nicotiana sp.), and is even used by symplastic loaders such as melon (Cucumis melo) under certain stress conditions. Reduction of the amount or complete removal of the transporters catalysing this transport step results in severe developmental defects. Here we present analyses of two Arabidopsis lines, suc2-4 and suc2-5, that carry a null allele of the SUC2 gene which encodes the Arabidopsis phloem loader. These lines were complemented with constructs expressing either the Arabidopsis SUC1 or the Ustilago maydis srt1 cDNA from the SUC2 promoter. Both SUC1 and Srt1 are energy-dependent sucrose/H(+) symporters and differ in specific kinetic properties from the SUC2 protein. Transgene expression was confirmed by RT-PCRs, the subcellular localization of Srt1 in planta with an Srt1-RFP fusion, and the correct CC-specific localization of the recombinant proteins by immunolocalization with anti-Srt1 and anti-SUC1 antisera. The transport capacity of Srt1 was studied in Srt1-GFP expressing Arabidopsis protoplasts. Although both proteins were found exclusively in CCs, only SUC1 complemented the developmental defects of suc2-4 and suc2-5 mutants. As SUC1 and Srt1 are well characterized, this result provides an insight into the properties that are essential for sucrose transporters to load the phloem successfully.
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Affiliation(s)
- Kathrin Wippel
- Molekulare Pflanzenphysiologie, Universität Erlangen-Nürnberg, Staudtstraße 5, D-91058 Erlangen, Germany
| | - Norbert Sauer
- Molekulare Pflanzenphysiologie, Universität Erlangen-Nürnberg, Staudtstraße 5, D-91058 Erlangen, Germany
- Erlangen Center of Plant Science (ECROPS), Universität Erlangen-Nürnberg, Staudtstraße 5, D-91058 Erlangen, Germany
- To whom correspondence should be addressed. E-mail:
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Chen LQ, Qu XQ, Hou BH, Sosso D, Osorio S, Fernie AR, Frommer WB. Sucrose efflux mediated by SWEET proteins as a key step for phloem transport. Science 2011; 335:207-11. [PMID: 22157085 DOI: 10.1126/science.1213351] [Citation(s) in RCA: 786] [Impact Index Per Article: 60.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Plants transport fixed carbon predominantly as sucrose, which is produced in mesophyll cells and imported into phloem cells for translocation throughout the plant. It is not known how sucrose migrates from sites of synthesis in the mesophyll to the phloem, or which cells mediate efflux into the apoplasm as a prerequisite for phloem loading by the SUT sucrose-H(+) (proton) cotransporters. Using optical sucrose sensors, we identified a subfamily of SWEET sucrose efflux transporters. AtSWEET11 and 12 localize to the plasma membrane of the phloem. Mutant plants carrying insertions in AtSWEET11 and 12 are defective in phloem loading, thus revealing a two-step mechanism of SWEET-mediated export from parenchyma cells feeding H(+)-coupled import into the sieve element-companion cell complex. We discuss how restriction of intercellular transport to the interface of adjacent phloem cells may be an effective mechanism to limit the availability of photosynthetic carbon in the leaf apoplasm in order to prevent pathogen infections.
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Affiliation(s)
- Li-Qing Chen
- Carnegie Institution for Science, 260 Panama Street, Stanford, CA 94305, USA
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Abstract
The majority of higher plants use sucrose as their main mobile carbohydrate. Proton-driven sucrose transporters play a crucial role in cell-to-cell and long-distance distribution of sucrose throughout the plant. A very negative plant membrane potential and the ability of sucrose transporters to accumulate sucrose concentrations of more than 1 M indicate that plants evolved transporters with unique structural and functional features. The knowledge about the transport mechanism and structural/functional domains of these nano-machines is, however, still fragmentary. In this review, the current knowledge about the biophysical properties of plant sucrose transporters is summarized and discussed.
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Affiliation(s)
- Dietmar Geiger
- Julius-von-Sachs Institute, Molecular Plant Physiology and Biophysics, University Würzburg, Julius-von-Sachs Platz 2, D-97082 Würzburg, Germany.
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