The Experts below are selected from a list of 18018 Experts worldwide ranked by ideXlab platform
Yongling Ruan - One of the best experts on this subject based on the ideXlab platform.
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understanding and manipulating sucrose phloem loading unloading metabolism and signalling to enhance crop yield and food security
Journal of Experimental Botany, 2014Co-Authors: David M Braun, Lu Wang, Yongling RuanAbstract:Sucrose is produced in, and translocated from, photosynthetically active leaves (sources) to support non-photosynthetic tissues (sinks), such as developing seeds, fruits, and tubers. Different plants can utilize distinct mechanisms to Transport sucrose into the phloem sieve tubes in source leaves. While phloem loading mechanisms have been extensively studied in dicot plants, there is less information about phloem loading in monocots. Maize and rice are major dietary staples, which have previously been proposed to use different cellular routes to Transport sucrose from photosynthetic cells into the translocation stream. The anatomical, physiological, and genetic evidence supporting these conflicting hypotheses is examined. Upon entering sink cells, sucrose often is degraded into hexoses for a wide range of metabolic and storage processes, including biosynthesis of starch, protein, and cellulose, which are all major constituents for food, fibre, and fuel. Sucrose, glucose, fructose, and their derivate, trehalose-6-phosphate, also serve as signalling molecules to regulate gene expression either directly or through cross-talk with other signalling pathways. As such, Sugar Transport and metabolism play pivotal roles in plant development and realization of crop yield that needs to be increased substantially to meet the projected population demand in the foreseeable future. This review will discuss the current understanding of the control of carbon partitioning from the cellular to whole-plant levels, focusing on (i) the pathways employed for phloem loading in source leaves, particularly in grasses, and the routes used in sink organs for phloem unloading; (ii) the Transporter proteins responsible for Sugar efflux and influx across plasma membranes; and (iii) the key enzymes regulating sucrose metabolism, signalling, and utilization. Examples of how Sugar Transport and metabolism can be manipulated to improve crop productivity and stress tolerance are discussed.
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understanding and manipulating sucrose phloem loading unloading metabolism and signalling to enhance crop yield and food security
Journal of Experimental Botany, 2014Co-Authors: David M Braun, Lu Wang, Yongling RuanAbstract:Sucrose is produced in, and translocated from, photosynthetically active leaves (sources) to support non-photosynthetic tissues (sinks), such as developing seeds, fruits, and tubers. Different plants can utilize distinct mechanisms to Transport sucrose into the phloem sieve tubes in source leaves. While phloem loading mechanisms have been extensively studied in dicot plants, there is less information about phloem loading in monocots. Maize and rice are major dietary staples, which have previously been proposed to use different cellular routes to Transport sucrose from photosynthetic cells into the translocation stream. The anatomical, physiological, and genetic evidence supporting these conflicting hypotheses is examined. Upon entering sink cells, sucrose often is degraded into hexoses for a wide range of metabolic and storage processes, including biosynthesis of starch, protein, and cellulose, which are all major constituents for food, fibre, and fuel. Sucrose, glucose, fructose, and their derivate, trehalose-6-phosphate, also serve as signalling molecules to regulate gene expression either directly or through cross-talk with other signalling pathways. As such, Sugar Transport and metabolism play pivotal roles in plant development and realization of crop yield that needs to be increased substantially to meet the projected population demand in the foreseeable future. This review will discuss the current understanding of the control of carbon partitioning from the cellular to whole-plant levels, focusing on (i) the pathways employed for phloem loading in source leaves, particularly in grasses, and the routes used in sink organs for phloem unloading; (ii) the Transporter proteins responsible for Sugar efflux and influx across plasma membranes; and (iii) the key enzymes regulating sucrose metabolism, signalling, and utilization. Examples of how Sugar Transport and metabolism can be manipulated to improve crop productivity and stress tolerance are discussed.
David M Braun - One of the best experts on this subject based on the ideXlab platform.
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understanding and manipulating sucrose phloem loading unloading metabolism and signalling to enhance crop yield and food security
Journal of Experimental Botany, 2014Co-Authors: David M Braun, Lu Wang, Yongling RuanAbstract:Sucrose is produced in, and translocated from, photosynthetically active leaves (sources) to support non-photosynthetic tissues (sinks), such as developing seeds, fruits, and tubers. Different plants can utilize distinct mechanisms to Transport sucrose into the phloem sieve tubes in source leaves. While phloem loading mechanisms have been extensively studied in dicot plants, there is less information about phloem loading in monocots. Maize and rice are major dietary staples, which have previously been proposed to use different cellular routes to Transport sucrose from photosynthetic cells into the translocation stream. The anatomical, physiological, and genetic evidence supporting these conflicting hypotheses is examined. Upon entering sink cells, sucrose often is degraded into hexoses for a wide range of metabolic and storage processes, including biosynthesis of starch, protein, and cellulose, which are all major constituents for food, fibre, and fuel. Sucrose, glucose, fructose, and their derivate, trehalose-6-phosphate, also serve as signalling molecules to regulate gene expression either directly or through cross-talk with other signalling pathways. As such, Sugar Transport and metabolism play pivotal roles in plant development and realization of crop yield that needs to be increased substantially to meet the projected population demand in the foreseeable future. This review will discuss the current understanding of the control of carbon partitioning from the cellular to whole-plant levels, focusing on (i) the pathways employed for phloem loading in source leaves, particularly in grasses, and the routes used in sink organs for phloem unloading; (ii) the Transporter proteins responsible for Sugar efflux and influx across plasma membranes; and (iii) the key enzymes regulating sucrose metabolism, signalling, and utilization. Examples of how Sugar Transport and metabolism can be manipulated to improve crop productivity and stress tolerance are discussed.
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understanding and manipulating sucrose phloem loading unloading metabolism and signalling to enhance crop yield and food security
Journal of Experimental Botany, 2014Co-Authors: David M Braun, Lu Wang, Yongling RuanAbstract:Sucrose is produced in, and translocated from, photosynthetically active leaves (sources) to support non-photosynthetic tissues (sinks), such as developing seeds, fruits, and tubers. Different plants can utilize distinct mechanisms to Transport sucrose into the phloem sieve tubes in source leaves. While phloem loading mechanisms have been extensively studied in dicot plants, there is less information about phloem loading in monocots. Maize and rice are major dietary staples, which have previously been proposed to use different cellular routes to Transport sucrose from photosynthetic cells into the translocation stream. The anatomical, physiological, and genetic evidence supporting these conflicting hypotheses is examined. Upon entering sink cells, sucrose often is degraded into hexoses for a wide range of metabolic and storage processes, including biosynthesis of starch, protein, and cellulose, which are all major constituents for food, fibre, and fuel. Sucrose, glucose, fructose, and their derivate, trehalose-6-phosphate, also serve as signalling molecules to regulate gene expression either directly or through cross-talk with other signalling pathways. As such, Sugar Transport and metabolism play pivotal roles in plant development and realization of crop yield that needs to be increased substantially to meet the projected population demand in the foreseeable future. This review will discuss the current understanding of the control of carbon partitioning from the cellular to whole-plant levels, focusing on (i) the pathways employed for phloem loading in source leaves, particularly in grasses, and the routes used in sink organs for phloem unloading; (ii) the Transporter proteins responsible for Sugar efflux and influx across plasma membranes; and (iii) the key enzymes regulating sucrose metabolism, signalling, and utilization. Examples of how Sugar Transport and metabolism can be manipulated to improve crop productivity and stress tolerance are discussed.
Ernest M Wright - One of the best experts on this subject based on the ideXlab platform.
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stochastic steps in secondary active Sugar Transport
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Joshua L Adelman, Ernest M Wright, Chiara Ghezzi, Paola Bisignano, Donald D F Loo, Seungho Choe, Jeff Abramson, John M Rosenberg, Michael GrabeAbstract:Secondary active Transporters, such as those that adopt the leucine-Transporter fold, are found in all domains of life, and they have the unique capability of harnessing the energy stored in ion gradients to accumulate small molecules essential for life as well as expel toxic and harmful compounds. How these proteins couple ion binding and Transport to the concomitant flow of substrates is a fundamental structural and biophysical question that is beginning to be answered at the atomistic level with the advent of high-resolution structures of Transporters in different structural states. Nonetheless, the dynamic character of the Transporters, such as ion/substrate binding order and how binding triggers conformational change, is not revealed from static structures, yet it is critical to understanding their function. Here, we report a series of molecular simulations carried out on the Sugar Transporter vSGLT that lend insight into how substrate and ions are released from the inward-facing state of the Transporter. Our simulations reveal that the order of release is stochastic. Functional experiments were designed to test this prediction on the human homolog, hSGLT1, and we also found that cytoplasmic release is not ordered, but we confirmed that substrate and ion binding from the extracellular space is ordered. Our findings unify conflicting published results concerning cytoplasmic release of ions and substrate and hint at the possibility that other Transporters in the superfamily may lack coordination between ions and substrate in the inward-facing state.
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active Sugar Transport in health and disease
Journal of Internal Medicine, 2007Co-Authors: Ernest M Wright, Bruce A HirayamaAbstract:Secondary active glucose Transport occurs by at least four members of the SLC5 gene family. This review considers the structure and function of two premier members, SGLT1 and SGLT2, and their role in intestinal glucose absorption and renal glucose reabsorption. Genetics disorders of SGLTs include Glucose-Galactose Malabsorption, and Familial Renal Glucosuria. SGLT1 plays a central role in Oral Rehydration Therapy used so effectively to treat secretory diarrhoea such as cholera. Increasing attention is being focused on SGLTs as drug targets for the therapy of diabetes.
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molecular basis for glucose galactose malabsorption
Cell Biochemistry and Biophysics, 2002Co-Authors: Ernest M Wright, Eric Turk, Martin G MartinAbstract:Glucose-galactose malabsorption (GGM) is an autosomal recessive disease that presents in newborn infants as a life-threatening diarrhea. The diarrhea ceases within 1 h of removing oral intake of lactose, glucose, and galactose, but promptly returns with the introduction of one or more of the offending Sugars into the diet. Our goal is to determine whether or not mutations in the sodium-glucose coTransporter gene (SGLT1) are responsible for GGM. We first isolated the human cDNA (hSGLT1), mapped the gene, and identified its chromosomal location (22q13.1). Our approach was then to screen GGM patients for mutations in hSGLT1 and then determine if these caused defects in Sugar Transport using the Xenopus laevis oocyte expression system. In 46 patients we have identified the mutations responsible for GGM. These included missense, nonsense, frame shift, splice site, and promoter mutations. In 30 patients, the same mutations were on both alleles, and the remaining 16 had different mutations on each allele (compound heterozygotes). Several mutations (e.g., C355S) were found in unrelated patients. The nonsense, frame shift, and splice site mutations all produce nonfunctional truncated proteins. In 22 out of the 23 missense mutations tested in the oocyte expression system, the proteins were translated and were stable in the cell, but did not reach the plasma membrane. In four of these mutants, an alanine residue was replaced by a valine, and in two, the trafficking defect was rescued by changing the valine to cysteine. One mutant protein (Q457R) did reach the plasma membrane, but it was unable to Transport the Sugar across the cell membrane. We conclude that mutations in the SGLT1 gene are the cause of glucose-galactose malabsorption, and Sugar Transport is impaired mainly because the mutant proteins are either truncated or are not targeted properly to the cell membrane.
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defects in na glucose coTransporter sglt1 trafficking and function cause glucose galactose malabsorption
Nature Genetics, 1996Co-Authors: Martin G Martin, M P Lostao, Eric Turk, Cynthia Kerner, Ernest M WrightAbstract:CoTransporters harness ion gradients to drive ‘active’ Transport of substrates into cells, for example, the Na+/glucose coTransporter (SGLT1) couples Sugar Transport to Na+ gradients across the intestinal brush border1. Glucose-Galactose Malabsorption (GGM) is caused by a defect in SGLT1. The phenotype is neonatal onset of diarrhea that results in death unless these Sugars are removed from the diet2–4. Previously we showed that two sisters with GGM had a missense mutation in the SGLT1 gene5. The gene has now been screened in 30 new patients, and a heterologous expression system has been used to link the mutations to the phenotype.
Annette Schurmann - One of the best experts on this subject based on the ideXlab platform.
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characterization of human glucose Transporter glut 11 encoded by slc2a11 a novel Sugar Transport facilitator specifically expressed in heart and skeletal muscle
Biochemical Journal, 2001Co-Authors: Holger Doege, Andrea Scheepers, Hans-georg Joost, Andreas Bocianski, Jurgen Eckel, Hubertus Axer, Annette SchurmannAbstract:Human GLUT11 (encoded by the solute carrier 2A11 gene, SLC2A11) is a novel Sugar Transporter which exhibits significant sequence similarity with the members of the GLUT family. The amino acid sequence deduced from its cDNAs predicts 12 putative membrane-spanning helices and all the motifs (Sugar-Transporter signatures) that have previously been shown to be essential for Sugar-Transport activity. The closest relative of GLUT11 is the fructose Transporter GLUT5 (sharing 41.7% amino acid identity with GLUT11). The human GLUT11 gene (SLC2A11) consists of 12 exons and is located on chromosome 22q11.2. In human tissues, a 7.2 kb transcript of GLUT11 was detected exclusively in heart and skeletal muscle. Transfection of COS-7 cells with GLUT11 cDNA significantly increased the glucose-Transport activity reconstituted from membrane extracts as well as the specific binding of the Sugar-Transporter ligand cytochalasin B. In contrast to that of GLUT4, the glucose-Transport activity of GLUT11 was markedly inhibited by fructose. It is concluded that GLUT11 is a novel, muscle-specific Transport facilitator that is a member of the extended GLUT family of Sugar/polyol-Transport facilitators.
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activity and genomic organization of human glucose Transporter 9 glut9 a novel member of the family of Sugar Transport facilitators predominantly expressed in brain and leucocytes
Biochemical Journal, 2000Co-Authors: Holger Doege, Hans-georg Joost, Andreas Bocianski, Annette SchurmannAbstract:The GLUT9 gene encodes a cDNA which exhibits significant sequence similarity with members of the glucose Transporter (GLUT) family. The gene is located on chromosome 9q34 and consists of 10 exons separated by short introns. The amino acid sequence deduced from its cDNA predicts 12 putative membrane-spanning helices and all the motifs (Sugar-Transporter signatures) that have previously been shown to be essential for Transport activity. A striking characteristic of GLUT9 is the presence of two arginines in the putative helices 7 and 8 at positions where the organic anion Transporters harbour basic residues. The next relative of GLUT9 is the glucose Transporter GLUT8/GLUTX1 (44.8% amino acid identity with GLUT9). A 2.6-kb transcript of GLUT9 was detected in spleen, peripheral leucocytes and brain. Transfection of COS-7 cells with GLUT9 produced expression of a 46-kDa membrane protein which exhibited reconstitutable glucose-Transport activity and low-affinity cytochalasin-B binding. It is concluded that GLUT9 is a novel member of the family of Sugar-Transport facilitators with a tissue-specific function.
Lu Wang - One of the best experts on this subject based on the ideXlab platform.
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understanding and manipulating sucrose phloem loading unloading metabolism and signalling to enhance crop yield and food security
Journal of Experimental Botany, 2014Co-Authors: David M Braun, Lu Wang, Yongling RuanAbstract:Sucrose is produced in, and translocated from, photosynthetically active leaves (sources) to support non-photosynthetic tissues (sinks), such as developing seeds, fruits, and tubers. Different plants can utilize distinct mechanisms to Transport sucrose into the phloem sieve tubes in source leaves. While phloem loading mechanisms have been extensively studied in dicot plants, there is less information about phloem loading in monocots. Maize and rice are major dietary staples, which have previously been proposed to use different cellular routes to Transport sucrose from photosynthetic cells into the translocation stream. The anatomical, physiological, and genetic evidence supporting these conflicting hypotheses is examined. Upon entering sink cells, sucrose often is degraded into hexoses for a wide range of metabolic and storage processes, including biosynthesis of starch, protein, and cellulose, which are all major constituents for food, fibre, and fuel. Sucrose, glucose, fructose, and their derivate, trehalose-6-phosphate, also serve as signalling molecules to regulate gene expression either directly or through cross-talk with other signalling pathways. As such, Sugar Transport and metabolism play pivotal roles in plant development and realization of crop yield that needs to be increased substantially to meet the projected population demand in the foreseeable future. This review will discuss the current understanding of the control of carbon partitioning from the cellular to whole-plant levels, focusing on (i) the pathways employed for phloem loading in source leaves, particularly in grasses, and the routes used in sink organs for phloem unloading; (ii) the Transporter proteins responsible for Sugar efflux and influx across plasma membranes; and (iii) the key enzymes regulating sucrose metabolism, signalling, and utilization. Examples of how Sugar Transport and metabolism can be manipulated to improve crop productivity and stress tolerance are discussed.
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understanding and manipulating sucrose phloem loading unloading metabolism and signalling to enhance crop yield and food security
Journal of Experimental Botany, 2014Co-Authors: David M Braun, Lu Wang, Yongling RuanAbstract:Sucrose is produced in, and translocated from, photosynthetically active leaves (sources) to support non-photosynthetic tissues (sinks), such as developing seeds, fruits, and tubers. Different plants can utilize distinct mechanisms to Transport sucrose into the phloem sieve tubes in source leaves. While phloem loading mechanisms have been extensively studied in dicot plants, there is less information about phloem loading in monocots. Maize and rice are major dietary staples, which have previously been proposed to use different cellular routes to Transport sucrose from photosynthetic cells into the translocation stream. The anatomical, physiological, and genetic evidence supporting these conflicting hypotheses is examined. Upon entering sink cells, sucrose often is degraded into hexoses for a wide range of metabolic and storage processes, including biosynthesis of starch, protein, and cellulose, which are all major constituents for food, fibre, and fuel. Sucrose, glucose, fructose, and their derivate, trehalose-6-phosphate, also serve as signalling molecules to regulate gene expression either directly or through cross-talk with other signalling pathways. As such, Sugar Transport and metabolism play pivotal roles in plant development and realization of crop yield that needs to be increased substantially to meet the projected population demand in the foreseeable future. This review will discuss the current understanding of the control of carbon partitioning from the cellular to whole-plant levels, focusing on (i) the pathways employed for phloem loading in source leaves, particularly in grasses, and the routes used in sink organs for phloem unloading; (ii) the Transporter proteins responsible for Sugar efflux and influx across plasma membranes; and (iii) the key enzymes regulating sucrose metabolism, signalling, and utilization. Examples of how Sugar Transport and metabolism can be manipulated to improve crop productivity and stress tolerance are discussed.
