1
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Hosen MJ, Hasan M, Chakraborty S, Abir RA, Zubaer A, Coucke P. Comprehensive in silico Study of GLUT10: Prediction of Possible Substrate Binding Sites and Interacting Molecules. Curr Pharm Biotechnol 2019; 21:117-130. [PMID: 31203799 DOI: 10.2174/1389201020666190613152030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 02/28/2019] [Accepted: 05/14/2019] [Indexed: 11/22/2022]
Abstract
OBJECTIVES The Arterial Tortuosity Syndrome (ATS) is an autosomal recessive connective tissue disorder, mainly characterized by tortuosity and stenosis of the arteries with a propensity towards aneurysm formation and dissection. It is caused by mutations in the SLC2A10 gene that encodes the facilitative glucose transporter GLUT10. The molecules transported by and interacting with GLUT10 have still not been unambiguously identified. Hence, the study attempts to identify both the substrate binding site of GLUT10 and the molecules interacting with this site. METHODS As High-resolution X-ray crystallographic structure of GLUT10 was not available, 3D homology model of GLUT10 in open conformation was constructed. Further, molecular docking and bioinformatics investigation were employed. RESULTS AND DISCUSSION Blind docking of nine reported potential in vitro substrates with this 3D homology model revealed that substrate binding site is possibly made with PRO531, GLU507, GLU437, TRP432, ALA506, LEU519, LEU505, LEU433, GLN525, GLN510, LYS372, LYS373, SER520, SER124, SER533, SER504, SER436 amino acid residues. Virtual screening of all metabolites from the Human Serum Metabolome Database and muscle metabolites from Human Metabolite Database (HMDB) against the GLUT10 revealed possible substrates and interacting molecules for GLUT10, which were found to be involved directly or partially in ATS progression or different arterial disorders. Reported mutation screening revealed that a highly emergent point mutation (c. 1309G>A, p. Glu437Lys) is located in the predicted substrate binding site region. CONCLUSION Virtual screening expands the possibility to explore more compounds that can interact with GLUT10 and may aid in understanding the mechanisms leading to ATS.
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Affiliation(s)
- Mohammad J Hosen
- Department of Genetic Engineering and Biotechnology, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh
| | - Mahmudul Hasan
- Department of Genetic Engineering and Biotechnology, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh.,Department of Pharmaceuticals and Industrial Biotechnology, Sylhet Agricultural University, Sylhet- 3100, Bangladesh.,CANSi Research Institute, Bioinformatics Laboratory, Sylhet, Bangladesh
| | - Sourav Chakraborty
- Department of Genetic Engineering and Biotechnology, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh.,CANSi Research Institute, Bioinformatics Laboratory, Sylhet, Bangladesh
| | - Ruhshan A Abir
- Department of Genetic Engineering and Biotechnology, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh.,CANSi Research Institute, Bioinformatics Laboratory, Sylhet, Bangladesh
| | - Abdullah Zubaer
- CANSi Research Institute, Bioinformatics Laboratory, Sylhet, Bangladesh.,Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Paul Coucke
- Center for Medical Genetics, Ghent University Hospital, Corneel Heymanslaan 10, Ghent 9000, Belgium
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2
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Léveillard T, Philp NJ, Sennlaub F. Is Retinal Metabolic Dysfunction at the Center of the Pathogenesis of Age-related Macular Degeneration? Int J Mol Sci 2019; 20:ijms20030762. [PMID: 30754662 PMCID: PMC6387069 DOI: 10.3390/ijms20030762] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 01/12/2023] Open
Abstract
The retinal pigment epithelium (RPE) forms the outer blood⁻retina barrier and facilitates the transepithelial transport of glucose into the outer retina via GLUT1. Glucose is metabolized in photoreceptors via the tricarboxylic acid cycle (TCA) and oxidative phosphorylation (OXPHOS) but also by aerobic glycolysis to generate glycerol for the synthesis of phospholipids for the renewal of their outer segments. Aerobic glycolysis in the photoreceptors also leads to a high rate of production of lactate which is transported out of the subretinal space to the choroidal circulation by the RPE. Lactate taken up by the RPE is converted to pyruvate and metabolized via OXPHOS. Excess lactate in the RPE is transported across the basolateral membrane to the choroid. The uptake of glucose by cone photoreceptor cells is enhanced by rod-derived cone viability factor (RdCVF) secreted by rods and by insulin signaling. Together, the three cells act as symbiotes: the RPE supplies the glucose from the choroidal circulation to the photoreceptors, the rods help the cones, and both produce lactate to feed the RPE. In age-related macular degeneration this delicate ménage à trois is disturbed by the chronic infiltration of inflammatory macrophages. These immune cells also rely on aerobic glycolysis and compete for glucose and produce lactate. We here review the glucose metabolism in the homeostasis of the outer retina and in macrophages and hypothesize what happens when the metabolism of photoreceptors and the RPE is disturbed by chronic inflammation.
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Affiliation(s)
- Thierry Léveillard
- . Department of Genetics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
| | - Nancy J Philp
- . Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
| | - Florian Sennlaub
- . Department of Therapeutics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
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3
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K Redhu A, Shah AH, Prasad R. MFS transporters of Candida species and their role in clinical drug resistance. FEMS Yeast Res 2016; 16:fow043. [PMID: 27188885 DOI: 10.1093/femsyr/fow043] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2016] [Indexed: 12/14/2022] Open
Abstract
ABC (ATP-binding cassette) and MFS (major facilitator superfamily) exporters, belonging to two different superfamilies, are one of the most prominent contributors of multidrug resistance (MDR) in yeast. While the role of ABC efflux pump proteins in the development of MDR is well documented, the MFS transporters which are also implicated in clinical drug resistance have not received due attention. The MFS superfamily is the largest known family of secondary active membrane carriers, and MFS exporters are capable of transporting a host of substrates ranging from small molecules, including organic and inorganic ions, to complex biomolecules, such as peptide and lipid moieties. A few of the members of the drug/H(+) antiporter family of the MFS superfamily function as multidrug transporters and employ downhill transport of protons to efflux their respective substrates. This review focuses on the recent developments in MFS of Candida and highlights their role in drug transport by using the example of the relatively well characterized promiscuous Mdr1 efflux pump of the pathogenic yeast C. albicans.
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Affiliation(s)
- Archana K Redhu
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Abdul H Shah
- Department of Bioresources, University of Kashmir, Srinagar 190006, India
| | - Rajendra Prasad
- Institute of Integrative Sciences and Health and Institute of Biotechnology, Amity University Haryana, Amity Education Valley, Gurgaon 122413, India
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Hu B, Wang W, Ou S, Tang J, Li H, Che R, Zhang Z, Chai X, Wang H, Wang Y, Liang C, Liu L, Piao Z, Deng Q, Deng K, Xu C, Liang Y, Zhang L, Li L, Chu C. Variation in NRT1.1B contributes to nitrate-use divergence between rice subspecies. Nat Genet 2015; 47:834-8. [PMID: 26053497 DOI: 10.1038/ng.3337] [Citation(s) in RCA: 358] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Accepted: 05/15/2015] [Indexed: 02/07/2023]
Abstract
Asian cultivated rice (Oryza sativa L.) consists of two main subspecies, indica and japonica. Indica has higher nitrate-absorption activity than japonica, but the molecular mechanisms underlying that activity remain elusive. Here we show that variation in a nitrate-transporter gene, NRT1.1B (OsNPF6.5), may contribute to this divergence in nitrate use. Phylogenetic analysis revealed that NRT1.1B diverges between indica and japonica. NRT1.1B-indica variation was associated with enhanced nitrate uptake and root-to-shoot transport and upregulated expression of nitrate-responsive genes. The selection signature of NRT1.1B-indica suggests that nitrate-use divergence occurred during rice domestication. Notably, field tests with near-isogenic and transgenic lines confirmed that the japonica variety carrying the NRT1.1B-indica allele had significantly improved grain yield and nitrogen-use efficiency (NUE) compared to the variety without that allele. Our results show that variation in NRT1.1B largely explains nitrate-use divergence between indica and japonica and that NRT1.1B-indica can potentially improve the NUE of japonica.
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Affiliation(s)
- Bin Hu
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Wei Wang
- 1] State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China. [2] College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shujun Ou
- 1] State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China. [2] Department of Horticulture, Michigan State University, East Lansing, Michigan, USA
| | - Jiuyou Tang
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Hua Li
- 1] State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China. [2] College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Ronghui Che
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Zhihua Zhang
- 1] State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China. [2] College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Xuyang Chai
- College of Life Science, Capital Normal University, Beijing, China
| | - Hongru Wang
- 1] State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China. [2] College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yiqin Wang
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Chengzhen Liang
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Linchuan Liu
- Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai, China
| | - Zhongze Piao
- Crop Breeding and Cultivation Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, China
| | - Qiyun Deng
- China National Hybrid Rice Research and Development Center, Changsha, China
| | - Kun Deng
- School of Agriculture, Henan University of Science and Technology, Luoyang, China
| | - Chi Xu
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yan Liang
- 1] State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China. [2] College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Lianhe Zhang
- School of Agriculture, Henan University of Science and Technology, Luoyang, China
| | - Legong Li
- College of Life Science, Capital Normal University, Beijing, China
| | - Chengcai Chu
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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Reznicek O, Facey S, de Waal P, Teunissen A, de Bont J, Nijland J, Driessen A, Hauer B. Improved xylose uptake in Saccharomyces cerevisiae
due to directed evolution of galactose permease Gal2 for sugar co-consumption. J Appl Microbiol 2015; 119:99-111. [DOI: 10.1111/jam.12825] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 04/01/2015] [Accepted: 04/08/2015] [Indexed: 12/19/2022]
Affiliation(s)
- O. Reznicek
- Institute of Technical Biochemistry; University of Stuttgart; Stuttgart Germany
| | - S.J. Facey
- Institute of Technical Biochemistry; University of Stuttgart; Stuttgart Germany
| | | | | | | | - J.G. Nijland
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology; Zernike Institute for Advanced Materials and Kluyver Centre for Genomics of Industrial Fermentation; University of Groningen; Groningen The Netherlands
| | - A.J.M. Driessen
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology; Zernike Institute for Advanced Materials and Kluyver Centre for Genomics of Industrial Fermentation; University of Groningen; Groningen The Netherlands
| | - B. Hauer
- Institute of Technical Biochemistry; University of Stuttgart; Stuttgart Germany
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Prasad R, Rawal MK. Efflux pump proteins in antifungal resistance. Front Pharmacol 2014; 5:202. [PMID: 25221515 PMCID: PMC4148622 DOI: 10.3389/fphar.2014.00202] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 08/13/2014] [Indexed: 11/13/2022] Open
Abstract
It is now well-known that the enhanced expression of ATP binding cassette (ABC) and major facilitator superfamily (MFS) proteins contribute to the development of tolerance to antifungals in yeasts. For example, the azole resistant clinical isolates of the opportunistic human fungal pathogen Candida albicans show an overexpression of Cdr1p and/or CaMdr1p belonging to ABC and MFS superfamilies, respectively. Hence, azole resistant isolates display reduced accumulation of therapeutic drug due to its rapid extrusion and that facilitates its survival. Considering the importance of major antifungal transporters, the focus of recent research has been to understand the structure and function of these proteins to design inhibitors/modulators to block the pump protein activity so that the drug already in use could again sensitize resistant yeast cells. The review focuses on the structure and function of ABC and MFS transporters of Candida to highlight the recent advancement in the field.
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Affiliation(s)
- Rajendra Prasad
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University New Delhi, India
| | - Manpreet K Rawal
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University New Delhi, India
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7
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Abstract
A major multidrug transporter, MDR1 (multidrug resistance 1), a member of the MFS (major facilitator superfamily), invariably contributes to an increased efflux of commonly used azoles and thus corroborates their direct involvement in MDR in Candida albicans. The Mdr1 protein has two transmembrane domains, each comprising six transmembrane helices, interconnected with extracellular loops and ICLs (intracellular loops). The introduction of deletions and insertions through mutagenesis was used to address the role of the largest interdomain ICL3 of the MDR1 protein. Most of the progressive deletants, when overexpressed, eliminated the drug resistance. Notably, restoration of the length of the ICL3 by insertional mutagenesis did not restore the functionality of the protein. Interestingly, most of the insertion and deletion variants of ICL3 became amenable to trypsinization, yielding peptide fragments. The homology model of the Mdr1 protein showed that the molecular surface-charge distribution was perturbed in most of the ICL3 mutant variants. Taken together, these results provide the first evidence that the CCL (central cytoplasmic loop) of the fungal MFS transporter of the DHA1 (drug/proton antiporter) family is critical for the function of MDR. Unlike other homologous proteins, ICL3 has no apparent role in imparting substrate specificity or in the recruitment of the transporter protein.
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8
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Lalioti VS, Vergarajauregui S, Tsuchiya Y, Hernandez-Tiedra S, Sandoval IV. Daxx functions as a scaffold of a protein assembly constituted by GLUT4, JNK1 and KIF5B. J Cell Physiol 2009; 218:416-26. [DOI: 10.1002/jcp.21614] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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9
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Abstract
GLUT1 deficiency syndrome (GLUT1DS, OMIM 606777) is a treatable epileptic encephalopathy resulting from impaired glucose transport into the brain. The essential biochemical finding is a low glucose concentration in the cerebrospinal fluid (CSF; hypoglycorrhachia; mean 1.7 [SD 0.3mmol/L]) in the setting of normoglycaemia. CSF lactate is normal. Patients present with an early-onset epilepsy resistant to anticonvulsants, developmental delay, and a complex movement disorder. Hypotonic, ataxic, and dystonic features are most prominent. Speech is often severely affected. Some patients develop spasticity and secondary microcephaly. The phenotype is highly variable ranging from severe impairment to children without seizures. Electroencephalography (EEG) may show 2.5-4Hz spike-waves improving on food intake. Neuroimaging is uninformative. Most patients carry heterozygous de novo mutations in the GLUT1 gene (OMIM 138140, gene map locus 1p35-31.3). Autosomal dominant transmission and several mutational hot spots have been identified, but phenotype-genotype correlations are not yet apparent. Homozygous GLUT1 mutations presumably are lethal. The ketogenic diet is the treatment of choice as it provides an alternative fuel to the brain. It should be introduced early and maintained into puberty. Seizures are effectively controlled with the onset of ketosis, but might recur and require comedication. The effect on neurodevelopment appears less impressive. The increasing number of patients, molecular and biochemical analysis, recent research into ketogenic diet mechanisms, and the development of animal models for GLUT1DS have brought substantial insights in disease manifestations and mechanisms. This review summarizes data on 84 published cases and highlights recent advances in understanding this entity.
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Blodgett DM, De Zutter JK, Levine KB, Karim P, Carruthers A. Structural basis of GLUT1 inhibition by cytoplasmic ATP. ACTA ACUST UNITED AC 2007; 130:157-68. [PMID: 17635959 PMCID: PMC2031153 DOI: 10.1085/jgp.200709818] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytoplasmic ATP inhibits human erythrocyte glucose transport protein (GLUT1)–mediated glucose transport in human red blood cells by reducing net glucose transport but not exchange glucose transport (Cloherty, E.K., D.L. Diamond, K.S. Heard, and A. Carruthers. 1996. Biochemistry. 35:13231–13239). We investigated the mechanism of ATP regulation of GLUT1 by identifying GLUT1 domains that undergo significant conformational change upon GLUT1–ATP interaction. ATP (but not GTP) protects GLUT1 against tryptic digestion. Immunoblot analysis indicates that ATP protection extends across multiple GLUT1 domains. Peptide-directed antibody binding to full-length GLUT1 is reduced by ATP at two specific locations: exofacial loop 7–8 and the cytoplasmic C terminus. C-terminal antibody binding to wild-type GLUT1 expressed in HEK cells is inhibited by ATP but binding of the same antibody to a GLUT1–GLUT4 chimera in which loop 6–7 of GLUT1 is substituted with loop 6–7 of GLUT4 is unaffected. ATP reduces GLUT1 lysine covalent modification by sulfo-NHS-LC-biotin by 40%. AMP is without effect on lysine accessibility but antagonizes ATP inhibition of lysine modification. Tandem electrospray ionization mass spectrometry analysis indicates that ATP reduces covalent modification of lysine residues 245, 255, 256, and 477, whereas labeling at lysine residues 225, 229, and 230 is unchanged. Exogenous, intracellular GLUT1 C-terminal peptide mimics ATP modulation of transport whereas C-terminal peptide-directed IgGs inhibit ATP modulation of glucose transport. These findings suggest that transport regulation involves ATP-dependent conformational changes in (or interactions between) the GLUT1 C terminus and the C-terminal half of GLUT1 cytoplasmic loop 6–7.
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Affiliation(s)
- David M Blodgett
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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11
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Jiang W, Ding Y, Su Y, Jiang M, Hu X, Zhang Z. Interaction of glucose transporter 1 with anion exchanger 1 in vitro. Biochem Biophys Res Commun 2006; 339:1255-61. [PMID: 16343432 DOI: 10.1016/j.bbrc.2005.11.138] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Accepted: 11/23/2005] [Indexed: 11/18/2022]
Abstract
The facilitative glucose transporter 1 (GLUT1) mediates the passive diffusion of d-glucose across the cell membrane, providing the energy resource in glycolysis in the erythrocytes. Anion exchanger 1 (band 3) is another important membrane protein that mediates rapid exchange of CO(2) through Cl(-)/HCO(3)(-) exchange across the erythrocyte membrane. For verifying the presumption over a decade that GLUT1 and band 3 in the erythrocyte would be interacting with each other, we cloned and expressed both the cytoplasmic domains of GLUT1 and band 3 in Escherichia coli, and tested their binding ability. By coimmunoprecipitation we found that among the tested N-terminal, C-terminal, and loop fraction of GLUT1, only the C-terminal of GLUT1 can interact with cytoplasmic domain of band 3. The interaction was further verified by coimmunoprecipitation and pull-down assay using both proteins as bait and target. These results showed that GLUT1 and band 3 form a protein complex that can regulate the activities of the proteins within it.
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Affiliation(s)
- Weihua Jiang
- Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China
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12
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Wang D, Pascual JM, Iserovich P, Yang H, Ma L, Kuang K, Zuniga FA, Sun RP, Swaroop KM, Fischbarg J, De Vivo DC. Functional studies of threonine 310 mutations in Glut1: T310I is pathogenic, causing Glut1 deficiency. J Biol Chem 2003; 278:49015-21. [PMID: 13129919 DOI: 10.1074/jbc.m308765200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously reported on a patient with the Glut1 deficiency syndrome (Online Mendelian Inheritance in Man number 606777) carrying a heterozygous T310I missense mutation in the GLUT1 gene (Klepper, J., Wang, D., Fischbarg, J., Vera, J. C., Jarjour, I. T., O'Driscoll, K. R., and De Vivo, D. C. (1999) Neurochem. Res. 24, 587-594). To investigate the molecular basis for the associated functional deficit, we constructed T310A, T310S, and T310I human GLUT1 mutants for expression in Xenopus laevis oocytes via cRNA injection. For all mutants, glucose transport was decreased, and osmotic water permeability (Pf) was increased. Km values for 3-O-methylglucose (3-OMG) uptake under zero-trans influx and equilibrium exchange influx conditions were, respectively, 13 +/- 1 and 68 +/- 5 mm for wild-type Glut1, 5 +/- 1 and 25 +/- 6 mm for T310A, 6 +/- 3 and 30 +/- 6 mm for T310I, and 5 +/- 1 and 48 +/- 5 mm for T310S. Compared with wild-type Glut1, we determined the following. (a). Zero-trans and equilibrium exchange influx values of 3-OMG were significantly decreased, respectively, 15 and 5% in T310A, 8 and 3% in T310I, and 40 and 34% in T310S mutants. (b). Zero-trans efflux of 3-OMG and dehydroascorbic acid uptake were significantly decreased in mutants. (c). The relative Pf values for T310A, T310I, and T310S were increased 3-, 4.8-, and 3.5-fold compared with wild-type values. We found a very high negative correlation between the rate of glucose uptake and Pf (-0.93), and between hydropathy and uptake (-0.92), a moderate correlation between hydropathy and Pf (0.73), and a minimal correlation between uptake, Pf, and molecular weight. These findings are consistent with a central role for hydropathy rather than size at position 310 of this mutation.
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Affiliation(s)
- Dong Wang
- Department of Neurology, Columbia University, New York, New York 10032, USA
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Lange P, Gertsen E, Monden I, Klepper J, Keller K. Functional consequences of an in vivo mutation in exon 10 of the human GLUT1 gene. FEBS Lett 2003; 555:274-8. [PMID: 14644427 DOI: 10.1016/s0014-5793(03)01247-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The functional consequences of an in vivo heterozygous insertion mutation in the human facilitated glucose transporter isoform 1 (GLUT1) gene were investigated. The resulting frameshift in exon 10 changed the primary structure of the C-terminus from 42 in native GLUT1 to 61 amino acid residues in the mutant. Kinetic studies on a patient's erythrocytes were substantiated by expressing the mutant cDNA in Xenopus laevis oocytes. K(m) and V(max) values were clearly decreased explaining pathogenicity. Targeting to the plasma membrane was comparable between mutant and wild-type GLUT1. Transport inhibition by cytochalasin B was more effective in the mutant than in the wild-type transporter. The substrate specificity of GLUT1 remained unchanged.
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Affiliation(s)
- Peter Lange
- Institute of Pharmacology, Freie Universität Berlin, Thielallee 67-73, D-14195 Berlin, Germany
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Reinders A, Schulze W, Thaminy S, Stagljar I, Frommer WB, Ward JM. Intra- and intermolecular interactions in sucrose transporters at the plasma membrane detected by the split-ubiquitin system and functional assays. Structure 2002; 10:763-72. [PMID: 12057192 DOI: 10.1016/s0969-2126(02)00773-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Interaction of two separately expressed halves of sucrose transporter SUT1 was detected by an optimized split-ubiquitin system. The halves reconstitute sucrose transport activity at the plasma membrane with affinities similar to the intact protein. The halves do not function independently, and an intact central loop is not required for membrane insertion, plasma membrane targeting, and transport. Under native conditions, the halves associate into higher molecular mass complexes. Furthermore, the N-terminal half of the low-affinity SUT2 interacts functionally with the C-terminal half of SUT1. Since the N terminus of SUT2 determines affinity for sucrose, the reconstituted chimera has lower affinity than SUT1. The split-ubiquitin system efficiently detects intramolecular interactions in membrane proteins, and can be used to dissect transporter structure.
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Affiliation(s)
- Anke Reinders
- Plant Biology, University of Minnesota, 220 Biological Sciences Center, 1445 Gortner Avenue, St. Paul, MN 55108, USA
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