1
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Sun W, Ding D, Bai D, Lin Y, Zhu Y, Zhang C, Zhang D. Transcriptomics and metabolomics analysis of L-phenylalanine overproduction in Escherichia coli. Microb Cell Fact 2023; 22:65. [PMID: 37024921 PMCID: PMC10080781 DOI: 10.1186/s12934-023-02070-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 03/24/2023] [Indexed: 04/08/2023] Open
Abstract
BACKGROUND Highly efficient production of L-phenylalanine (L-Phe) in E. coli has been achieved by multiple rounds of random mutagenesis and modification of key genes of the shikimate (SHIK) and L-Phe branch pathways. In this study, we performed transcriptomic (16, 24 and 48 h) and metabolomic analyses (8, 16, 24, 32,40, and 48 h) based on time sequences in an engineered E. coli strain producing L-Phe, aiming to reveal the overall changes of metabolic activities during the fermentation process. RESULTS The largest biomass increase rate and the highest production rate were seen at 16 h and 24 h of fermentation, respectively reaching 5.9 h-1 and 2.76 g/L/h, while the maximal L-Phe titer of 60 g/L was accumulated after 48 h of fermentation. The DEGs and metabolites involved in the EMP, PP, TCA, SHIIK and L-Phe-branch pathways showed significant differences at different stages of fermentation. Specifically, the significant upregulation of genes encoding rate-limiting enzymes (aroD and yidB) and key genes (aroF, pheA and aspC) pushed more carbon flux toward the L-Phe synthesis. The RIA changes of a number of important metabolites (DAHP, DHS, DHQ, Glu and PPN) enabled the adequate supply of precursors for high-yield L-Phe production. In addition, other genes related to Glc transport and phosphate metabolism increased the absorption of Glc and contributed to rerouting the carbon flux into the L-Phe-branch. CONCLUSIONS Transcriptomic and metabolomic analyses of an L-Phe overproducing strain of E. coli confirmed that precursor supply was not a major limiting factor in this strain, whereas the rational distribution of metabolic fluxes was achieved by redistributing the carbon flux (for example, the expression intensity of the genes tyrB, aspC, aroL and aroF/G/H or the activity of these enzymes is increased to some extent), which is the optimal strategy for enhancing L-Phe production.
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Affiliation(s)
- Wei Sun
- School of Biological Engineering, Tianjin University of Science and Technology, Tianjin, 300457, China
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Dongqin Ding
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Danyang Bai
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Yang Lin
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Yaru Zhu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Cuiying Zhang
- School of Biological Engineering, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Dawei Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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2
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Jia R, Bradshaw RT, Calvaresi V, Politis A. Integrating Hydrogen Deuterium Exchange-Mass Spectrometry with Molecular Simulations Enables Quantification of the Conformational Populations of the Sugar Transporter XylE. J Am Chem Soc 2023; 145:7768-7779. [PMID: 36976935 PMCID: PMC10103171 DOI: 10.1021/jacs.2c06148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
A yet unresolved challenge in structural biology is to quantify the conformational states of proteins underpinning function. This challenge is particularly acute for membrane proteins owing to the difficulties in stabilizing them for in vitro studies. To address this challenge, we present an integrative strategy that combines hydrogen deuterium exchange-mass spectrometry (HDX-MS) with ensemble modeling. We benchmark our strategy on wild-type and mutant conformers of XylE, a prototypical member of the ubiquitous Major Facilitator Superfamily (MFS) of transporters. Next, we apply our strategy to quantify conformational ensembles of XylE embedded in different lipid environments. Further application of our integrative strategy to substrate-bound and inhibitor-bound ensembles allowed us to unravel protein-ligand interactions contributing to the alternating access mechanism of secondary transport in atomistic detail. Overall, our study highlights the potential of integrative HDX-MS modeling to capture, accurately quantify, and subsequently visualize co-populated states of membrane proteins in association with mutations and diverse substrates and inhibitors.
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Affiliation(s)
- Ruyu Jia
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, U.K
| | - Richard T Bradshaw
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, U.K
| | - Valeria Calvaresi
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, U.K
| | - Argyris Politis
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, U.K
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester M13 9PT, U.K
- Manchester Institute of Biotechnology, University of Manchester, Princess Street, Manchester M1 7DN, U.K
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3
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Chen LY. Quantitative characterization of the path of glucose diffusion facilitated by human glucose transporter 1. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183975. [PMID: 35654150 DOI: 10.1016/j.bbamem.2022.183975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Glucose transporter GLUT1 is ubiquitously expressed in the human body from the red cells to the blood-brain barrier to the skeletal muscles. It is physiologically relevant to understand how GLUT1 facilitates diffusion of glucose across the cell membrane. It is also pathologically relevant because GLUT1 deficiency causes neurological disorders and anemia and because GLUT1 overexpression fuels the abnormal growth of cancer cells. This article presents a quantitative investigation of GLUT1 based on all-atom molecular-dynamics (MD) simulations of the transporter embedded in lipid bilayers of asymmetric inner-and-outer-leaflet lipid compositions, subject to asymmetric intra-and-extra-cellular environments. This is in contrast with the current literature of MD studies that have not considered both of the aforementioned asymmetries of the cell membrane. The equilibrium (unbiased) dynamics of GLUT1 shows that it can facilitate glucose diffusion across the cell membrane without undergoing large-scale conformational motions. The Gibbs free-energy profile, which is still lacking in the current literature of GLUT1, quantitatively characterizes the diffusion path of glucose from the periplasm, through an extracellular gate of GLUT1, on to the binding site, and off to the cytoplasm. This transport mechanism is validated by the experimental data that GLUT1 has low water-permeability, uptake-efflux symmetry, and 10 kcal/mol Arrhenius activation barrier around 37 °C.
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Affiliation(s)
- Liao Y Chen
- Department of Physics, The University of Texas at San Antonio, San Antonio, TX 78249, USA.
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4
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Li Y, Gong H. Identifying a Feasible Transition Pathway between Two Conformational States for a Protein. J Chem Theory Comput 2022; 18:4529-4543. [PMID: 35723447 DOI: 10.1021/acs.jctc.2c00390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Proteins usually need to transit between different conformational states to fulfill their biological functions. In the mechanistic study of such transition processes by molecular dynamics simulations, identification of the minimum free energy path (MFEP) can substantially reduce the sampling space, thus enabling rigorous thermodynamic evaluation of the process. Conventionally, the MFEP is derived by iterative local optimization from an initial path, which is typically generated by simple brute force techniques like the targeted molecular dynamics (tMD). Therefore, the quality of the initial path determines the successfulness of MFEP estimation. In this work, we propose a method to improve derivation of the initial path. Through iterative relaxation-biasing simulations in a bidirectional manner, this method can construct a feasible transition pathway connecting two known states for a protein. Evaluation on small, fast-folding proteins against long equilibrium trajectories supports the good sampling efficiency of our method. When applied to larger proteins including the catalytic domain of human c-Src kinase as well as the converter domain of myosin VI, the paths generated by our method deviate significantly from those computed with the generic tMD approach. More importantly, free energy profiles and intermediate states obtained from our paths exhibit remarkable improvements over those from tMD paths with respect to both physical rationality and consistency with a priori knowledge.
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Affiliation(s)
- Yao Li
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Haipeng Gong
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
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5
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Chen H, Ogden D, Pant S, Cai W, Tajkhorshid E, Moradi M, Roux B, Chipot C. A Companion Guide to the String Method with Swarms of Trajectories: Characterization, Performance, and Pitfalls. J Chem Theory Comput 2022; 18:1406-1422. [PMID: 35138832 PMCID: PMC8904302 DOI: 10.1021/acs.jctc.1c01049] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The string method with swarms of trajectories (SMwST) is an algorithm that identifies a physically meaningful transition pathway─a one-dimensional curve, embedded within a high-dimensional space of selected collective variables. The SMwST algorithm leans on a series of short, unbiased molecular dynamics simulations spawned at different locations of the discretized path, from whence an average dynamic drift is determined to evolve the string toward an optimal pathway. However conceptually simple in both its theoretical formulation and practical implementation, the SMwST algorithm is computationally intensive and requires a careful choice of parameters for optimal cost-effectiveness in applications to challenging problems in chemistry and biology. In this contribution, the SMwST algorithm is presented in a self-contained manner, discussing with a critical eye its theoretical underpinnings, applicability, inherent limitations, and use in the context of path-following free-energy calculations and their possible extension to kinetics modeling. Through multiple simulations of a prototypical polypeptide, combining the search of the transition pathway and the computation of the potential of mean force along it, several practical aspects of the methodology are examined with the objective of optimizing the computational effort, yet without sacrificing accuracy. In light of the results reported here, we propose some general guidelines aimed at improving the efficiency and reliability of the computed pathways and free-energy profiles underlying the conformational transitions at hand.
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Affiliation(s)
- Haochuan Chen
- Research Center for Analytical Sciences, College of Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Nankai University, Tianjin 300071, China
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, Unité Mixte de Recherche no 7019, Université de Lorraine, B.P. 70239, 54506 Vandœuvre-lès-Nancy Cedex, France
| | - Dylan Ogden
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Shashank Pant
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Wensheng Cai
- Research Center for Analytical Sciences, College of Chemistry, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Nankai University, Tianjin 300071, China
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Biochemistry and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Benoît Roux
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, United States
| | - Christophe Chipot
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, Unité Mixte de Recherche no 7019, Université de Lorraine, B.P. 70239, 54506 Vandœuvre-lès-Nancy Cedex, France
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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6
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Bavnhøj L, Paulsen PA, Flores-Canales JC, Schiøtt B, Pedersen BP. Molecular mechanism of sugar transport in plants unveiled by structures of glucose/H + symporter STP10. NATURE PLANTS 2021; 7:1409-1419. [PMID: 34556835 DOI: 10.1038/s41477-021-00992-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 07/27/2021] [Indexed: 05/28/2023]
Abstract
Sugars are essential sources of energy and carbon and also function as key signalling molecules in plants. Sugar transport proteins (STP) are proton-coupled symporters responsible for uptake of glucose from the apoplast into plant cells. They are integral to organ development in symplastically isolated tissues such as seed, pollen and fruit. Additionally, STPs play a vital role in plant responses to stressors such as dehydration and prevalent fungal infections like rust and mildew. Here we present a structure of Arabidopsis thaliana STP10 in the inward-open conformation at 2.6 Å resolution and a structure of the outward-occluded conformation at improved 1.8 Å resolution, both with glucose and protons bound. The two structures describe key states in the STP transport cycle. Together with molecular dynamics simulations that establish protonation states and biochemical analysis, they pinpoint structural elements, conserved in all STPs, that clarify the basis of proton-to-glucose coupling. These results advance our understanding of monosaccharide uptake, which is essential for plant organ development, and set the stage for bioengineering strategies in crops.
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Affiliation(s)
- Laust Bavnhøj
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Peter Aasted Paulsen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | | | - Birgit Schiøtt
- Department of Chemistry, Aarhus University, Aarhus, Denmark
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7
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Drew D, North RA, Nagarathinam K, Tanabe M. Structures and General Transport Mechanisms by the Major Facilitator Superfamily (MFS). Chem Rev 2021; 121:5289-5335. [PMID: 33886296 PMCID: PMC8154325 DOI: 10.1021/acs.chemrev.0c00983] [Citation(s) in RCA: 165] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Indexed: 12/12/2022]
Abstract
The major facilitator superfamily (MFS) is the largest known superfamily of secondary active transporters. MFS transporters are responsible for transporting a broad spectrum of substrates, either down their concentration gradient or uphill using the energy stored in the electrochemical gradients. Over the last 10 years, more than a hundred different MFS transporter structures covering close to 40 members have provided an atomic framework for piecing together the molecular basis of their transport cycles. Here, we summarize the remarkable promiscuity of MFS members in terms of substrate recognition and proton coupling as well as the intricate gating mechanisms undergone in achieving substrate translocation. We outline studies that show how residues far from the substrate binding site can be just as important for fine-tuning substrate recognition and specificity as those residues directly coordinating the substrate, and how a number of MFS transporters have evolved to form unique complexes with chaperone and signaling functions. Through a deeper mechanistic description of glucose (GLUT) transporters and multidrug resistance (MDR) antiporters, we outline novel refinements to the rocker-switch alternating-access model, such as a latch mechanism for proton-coupled monosaccharide transport. We emphasize that a full understanding of transport requires an elucidation of MFS transporter dynamics, energy landscapes, and the determination of how rate transitions are modulated by lipids.
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Affiliation(s)
- David Drew
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Rachel A. North
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Kumar Nagarathinam
- Center
of Structural and Cell Biology in Medicine, Institute of Biochemistry, University of Lübeck, D-23538, Lübeck, Germany
| | - Mikio Tanabe
- Structural
Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan
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8
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Tian Y, Shen S, Gu L, Zhou J, Li Y, Zheng X. Computer-aided design of glucoside brain-targeted molecules based on 4PYP. J Mol Graph Model 2021; 103:107819. [DOI: 10.1016/j.jmgm.2020.107819] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 12/13/2022]
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9
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Hydrogen-deuterium exchange mass spectrometry captures distinct dynamics upon substrate and inhibitor binding to a transporter. Nat Commun 2020; 11:6162. [PMID: 33268777 PMCID: PMC7710758 DOI: 10.1038/s41467-020-20032-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 10/15/2020] [Indexed: 11/13/2022] Open
Abstract
Proton-coupled transporters use transmembrane proton gradients to power active transport of nutrients inside the cell. High-resolution structures often fail to capture the coupling between proton and ligand binding, and conformational changes associated with transport. We combine HDX-MS with mutagenesis and MD simulations to dissect the molecular mechanism of the prototypical transporter XylE. We show that protonation of a conserved aspartate triggers conformational transition from outward-facing to inward-facing state. This transition only occurs in the presence of substrate xylose, while the inhibitor glucose locks the transporter in the outward-facing state. MD simulations corroborate the experiments by showing that only the combination of protonation and xylose binding, and not glucose, sets up the transporter for conformational switch. Overall, we demonstrate the unique ability of HDX-MS to distinguish between the conformational dynamics of inhibitor and substrate binding, and show that a specific allosteric coupling between substrate binding and protonation is a key step to initiate transport. XylE is a bacterial xylose transporter and homologue of human glucose transporters GLUTs 1-4. HDX-MS, mutagenesis and MD simulations suggest that protonation of a conserved aspartate triggers conformational transition from outward- to inward facing state only in the presence of substrate xylose. In contrast, inhibitor glucose locks the transporter in the outward facing state.
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10
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Transporters of glucose and other carbohydrates in bacteria. Pflugers Arch 2020; 472:1129-1153. [PMID: 32372286 DOI: 10.1007/s00424-020-02379-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 12/18/2022]
Abstract
Glucose arguably is the most important energy carrier, carbon source for metabolites and building block for biopolymers in all kingdoms of life. The proper function of animal organs and tissues depends on the continuous supply of glucose from the bloodstream. Most animals can resorb only a small number of monosaccharides, mostly glucose, galactose and fructose, while all other sugars oligosaccharides and dietary fibers are degraded and metabolized by the microbiota of the lower intestine. Bacteria, in contrast, are omnivorous. They can import and metabolize structurally different sugars and, as a consortium of different species, utilize almost any sugar, sugar derivative and oligosaccharide occurring in nature. Bacteria have membrane transport systems for the uptake of sugars against steep concentration gradients energized by ATP, the proton motive force and the high energy glycolytic intermediate phosphoenolpyruvate (PEP). Different uptake mechanisms and the broad range of overlapping substrate specificities allow bacteria to quickly adapt to and colonize changing environments. Here, we review the structures and mechanisms of bacterial representatives of (i) ATP-dependent cassette (ABC) transporters, (ii) major facilitator (MFS) superfamily proton symporters, (iii) sodium solute symporters (SSS) and (iv) enzyme II integral membrane subunits of the bacterial PEP-dependent phosphotransferase system (PTS). We give a short overview on the distribution of transporter genes and their phylogenetic relationship in different bacterial species. Some sugar transporters are hijacked for import of bacteriophage DNA and antibacterial toxins (bacteriocins) and they facilitate the penetration of polar antibiotics. Finally, we describe how the expression and activity of certain sugar transporters are controlled in response to the availability of sugars and how the presence and uptake of sugars may affect pathogenicity and host-microbiota interactions.
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11
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Tamura K, Sugita Y. Free Energy Analysis of a Conformational Change of Heme ABC Transporter BhuUV-T. J Phys Chem Lett 2020; 11:2824-2829. [PMID: 32202796 PMCID: PMC10961826 DOI: 10.1021/acs.jpclett.0c00547] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The heme ATP-binding cassette (ABC) transporter BhuUV-T of bacterial pathogen Burkholderia cenocepacia is required to transport heme across the inner cell membrane. The current hypothesis is that the binding of two ATPs to the nucleotide-binding domains of the transporter drives the initial steps of the transport cycle in which the empty transport sites are reoriented from the cytosol to the periplasm. Molecular details are missing because the structure of a key occluded intermediate remains hypothetical. Here we perform molecular simulations to analyze the free energy surface (FES) of the first step of the reorientation, namely the transition from an open inward-facing (IF) transport site to an occluded (Occ) conformation. We have modeled the latter structure in silico in a previous study. A simple annealing procedure removes residual bias originating from non-equilibrium targeted molecular dynamics. The calculated FES reveals the role of the ATPs in inducing the IF → Occ conformational change and validates the modeled Occ conformation.
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Affiliation(s)
- Koichi Tamura
- Computational Biophysics
Research
Team, RIKEN Center for Computational Science, 6-7-1 minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Yuji Sugita
- Computational Biophysics
Research
Team, RIKEN Center for Computational Science, 6-7-1 minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Laboratory for Biomolecular Function
Simulation, RIKEN Center for Biosystems
Dynamics Research, 6-7-1
minatojima-Minamimachi,
Chuo-ku, Kobe, Hyogo 650-0047, Japan
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12
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Zhao L, Zhang H, Wang X, Han G, Ma W, Hu X, Li Y. Transcriptomic analysis of an l-threonine-producing Escherichia coli TWF001. Biotechnol Appl Biochem 2020; 67:414-429. [PMID: 31976571 DOI: 10.1002/bab.1890] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 01/21/2020] [Indexed: 01/10/2023]
Abstract
Wild-type Escherichia coli usually does not accumulate l-threonine, but E. coli strain TWF001 could produce 30.35 g/L l-threonine after 23-H fed-batch fermentation. To understand the mechanism for the high yield of l-threonine production in TWF001, transcriptomic analyses of the TWF001 cell samples collected at the logarithmic and stationary phases were performed, using the wild-type E. coli strain W3110 as the control. Compared with W3110, 1739 and 2361 genes were differentially transcribed in the logarithmic and stationary phases, respectively. Most genes related to the biosynthesis of l-threonine were significantly upregulated. Some key genes related to the NAD(P)H regeneration were upregulated. Many genes relevant to glycolysis and TCA cycle were downregulated. The key genes involved in the l-threonine degradation were downregulated. The gene rhtA encoding the l-threonine exporter was upregulated, whereas the genes sstT and tdcC encoding the l-threonine importer were downregulated. The upregulated genes in the glutamate pathway might form an amino-providing loop, which is beneficial for the high yield of l-threonine production. Many genes encoding the 30S and 50S subunits of ribosomes were also upregulated. The findings are useful for gene engineering to increase l-threonine production in E. coli.
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Affiliation(s)
- Lei Zhao
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Hailing Zhang
- Department of Biological Engineering, College of Life Science, Yantai University, Shandong, 408100, China
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Guoqiang Han
- College of Modern Agriculture and Biological Engineering, Yangtze Normal University, Chongqing, 264005, China
| | - Wenjian Ma
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Xiaoqing Hu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Ye Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
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13
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Chen LY, Phelix CF. Extracellular gating of glucose transport through GLUT 1. Biochem Biophys Res Commun 2019; 511:573-578. [PMID: 30824189 PMCID: PMC6452493 DOI: 10.1016/j.bbrc.2019.02.067] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 02/13/2019] [Indexed: 11/18/2022]
Abstract
The ubiquitous glucose transporter 1 (GLUT1) is physiologically and pathologically relevant in energy metabolism of the CNS, skeletal muscles, cancer cells etc. Extensive experiments on GLUT1 produced thorough understandings of its expressions, functions, and structures which were recently resolved to atomic accuracy. However, theoretical understandings are still controversial about how GLUT1 facilitates glucose diffusion across the cell membrane. Molecular dynamics (MD) simulations of the current literature have GLUT1 embedded in a symmetric bilayer of a single lipid type. They provide atomistic illustrations of the alternating access theory (AAT), but the simulation results are inconsistent with the undisputed experimental data of kinetics showing rapid transport of glucose at near-physiological temperatures, high Arrhenius activation barrier in zero-trans uptake, and large trans-acceleration at sub-physiological temperatures. In this research, we embedded GLUT1 in an asymmetric bilayer of multiple lipids to better mimic the erythrocyte membrane. We ran unbiased MD simulations at 37 °C and at 5 °C and found a new mechanism of glucose transport via GLUT1: The extracellular (EC) gate opened wide for EC glucopyranose at 37 °C and, only in the presence of intracellular (IC) glucose, at 5 °C. In the absence of IC glucose at 5 °C, the EC gate opened narrowly for acyclic glucose, gating out glucopyranose. This EC-gating mechanism is simpler than AAT and yet it well explains for the rapid glucose transport at near-physiological temperatures and large trans-acceleration at sub-physiological temperatures. It also explains why zero-trans uptake (involving the pyranose-to-aldehyde transformation) has an Arrhenius barrier ∼20 kcal/mol higher than the equilibrium exchange transport.
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Affiliation(s)
- Liao Y Chen
- Department of Physics, University of Texas at San Antonio, San Antonio, TX, 78249, USA.
| | - Clyde F Phelix
- Department of Biology, University of Texas at San Antonio, San Antonio, TX, 78249, USA
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14
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Galochkina T, Ng Fuk Chong M, Challali L, Abbar S, Etchebest C. New insights into GluT1 mechanics during glucose transfer. Sci Rep 2019; 9:998. [PMID: 30700737 PMCID: PMC6353926 DOI: 10.1038/s41598-018-37367-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 11/28/2018] [Indexed: 11/17/2022] Open
Abstract
Glucose plays a crucial role in the mammalian cell metabolism. In the erythrocytes and endothelial cells of the blood-brain barrier, glucose uptake is mediated by the glucose transporter type 1 (GluT1). GluT1 deficiency or mutations cause severe physiological disorders. GluT1 is also an important target in cancer therapy as it is overexpressed in tumor cells. Previous studies have suggested that GluT1 mediates solute transfer through a cycle of conformational changes. However, the corresponding 3D structures adopted by the transporter during the transfer process remain elusive. In the present work, we first elucidate the whole conformational landscape of GluT1 in the absence of glucose, using long molecular dynamics simulations and show that the transitions can be accomplished through thermal fluctuations. Importantly, we highlight a strong coupling between intracellular and extracellular domains of the protein that contributes to the transmembrane helices reorientation during the transition. The conformations adopted during the simulations differ from the known 3D bacterial homologs structures resolved in similar states. In holo state simulations, we find that glucose transits along the pathway through significant rotational motions, while maintaining hydrogen bonds with the protein. These persistent motions affect side chains orientation, which impacts protein mechanics and allows glucose progression.
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Affiliation(s)
- Tatiana Galochkina
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR S1134, DSIMB, Laboratoire d'Excellence GR-Ex, Paris, 75739, France
| | - Matthieu Ng Fuk Chong
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR S1134, DSIMB, Laboratoire d'Excellence GR-Ex, Paris, 75739, France
| | - Lylia Challali
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR S1134, DSIMB, Laboratoire d'Excellence GR-Ex, Paris, 75739, France
| | - Sonia Abbar
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR S1134, DSIMB, Laboratoire d'Excellence GR-Ex, Paris, 75739, France
| | - Catherine Etchebest
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR S1134, DSIMB, Laboratoire d'Excellence GR-Ex, Paris, 75739, France.
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15
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Liao YY, Li JL, Pan RL, Chiou TJ. Structure-Function Analysis Reveals Amino Acid Residues of Arabidopsis Phosphate Transporter AtPHT1;1 Crucial for Its Activity. FRONTIERS IN PLANT SCIENCE 2019; 10:1158. [PMID: 31608095 PMCID: PMC6761603 DOI: 10.3389/fpls.2019.01158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/26/2019] [Indexed: 05/05/2023]
Abstract
Phosphorus (P), an essential plant macronutrient, is acquired in the form of inorganic phosphate (Pi) by transporters located at the plasma membrane of root cells. To decipher the Pi transport mechanism, Arabidopsis thaliana Pi transporter 1;1 (AtPHT1;1), the most predominantly H+-coupled Pi co-transporter in the root, was selected for structure-function analysis. We first predicted its secondary and tertiary structures on the basis of the Piriformospora indica Pi transporter (PiPT) and identified 28 amino acid residues potentially engaged in the activity of AtPHT1;1. We then mutagenized these residues into alanine and expressed them in the yeast pam2 mutant defective in high-affinity Pi transporters and Arabidopsis pht1;1 mutant, respectively, for functional complementation validation. We further incorporated the functional characterization and structure analyses to propose a mechanistic model for the function of AtPHT1;1. We showed that D35, D38, R134, and D144, implicated in H+ transfer across the membrane, and Y312 and N421, involved in initial interaction and translocation of Pi, are all essential for its transport activity. When Pi enters the binding pocket, the two aromatic moieties of Y145 and F169 and the hydrogen bonds generated from Q172, W304, Y312, D308, and K449 can build a scaffold to stabilize the structure. Subsequent interaction between Pi and the positive residue of K449 facilitates its release. Furthermore, D38, D93, R134, D144, D212, R216, R233, D367, K373, and E504 may form internal electrostatic interactions for structure ensemble and adaptability. This study offers a comprehensive model for elucidating the transport mechanism of a plant Pi transporter.
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Affiliation(s)
- Ya-Yun Liao
- Department of Life Science, Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsin Chu, Taiwan
| | - Jia-Ling Li
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
| | - Rong-Long Pan
- Department of Life Science, Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsin Chu, Taiwan
- *Correspondence: Tzyy-Jen Chiou, ; Rong-Long Pan,
| | - Tzyy-Jen Chiou
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
- *Correspondence: Tzyy-Jen Chiou, ; Rong-Long Pan,
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16
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Henderson RK, Fendler K, Poolman B. Coupling efficiency of secondary active transporters. Curr Opin Biotechnol 2018; 58:62-71. [PMID: 30502621 DOI: 10.1016/j.copbio.2018.11.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 11/14/2018] [Indexed: 10/27/2022]
Abstract
Secondary active transporters are fundamental to a myriad of biological processes. They use the electrochemical gradient of one solute to drive transport of another solute against its concentration gradient. Central to this mechanism is that the transport of one does not occur in the absence of the other. However, like in most of biology, imperfections in the coupling mechanism exist and we argue that these are innocuous and may even be beneficial for the cell. We discuss the energetics and kinetics of alternating-access in secondary transport and focus on the mechanistic aspects of imperfect coupling that give rise to leak pathways. Additionally, inspection of available transporter structures gives valuable insight into coupling mechanics, and we review literature where proteins have been altered to change their coupling efficiency.
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Affiliation(s)
- Ryan K Henderson
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Klaus Fendler
- Department of Biophysical Chemistry, Max-Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Bert Poolman
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
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17
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Liang H, Bourdon AK, Chen LY, Phelix CF, Perry G. Gibbs Free-Energy Gradient along the Path of Glucose Transport through Human Glucose Transporter 3. ACS Chem Neurosci 2018; 9:2815-2823. [PMID: 29865792 PMCID: PMC6256350 DOI: 10.1021/acschemneuro.8b00223] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
![]()
Fourteen
glucose transporters (GLUTs) play essential roles in human
physiology by facilitating glucose diffusion across the cell membrane.
Due to its central role in the energy metabolism of the central nervous
system, GLUT3 has been thoroughly investigated. However, the Gibbs
free-energy gradient (what drives the facilitated diffusion of glucose)
has not been mapped out along the transport path. Some fundamental
questions remain. Here we present a molecular dynamics study of GLUT3
embedded in a lipid bilayer to quantify the free-energy profile along
the entire transport path of attracting a β-d-glucose
from the interstitium to the inside of GLUT3 and, from there, releasing
it to the cytoplasm by Arrhenius thermal activation. From the free-energy
profile, we elucidate the unique Michaelis–Menten characteristics
of GLUT3, low KM and high VMAX, specifically suitable for neurons’ high and
constant demand of energy from their low-glucose environments. We
compute GLUT3’s binding free energy for β-d-glucose
to be −4.6 kcal/mol in agreement with the experimental value
of −4.4 kcal/mol (KM = 1.4 mM).
We also compute the hydration energy of β-d-glucose,
−18.0 kcal/mol vs the experimental data, −17.8 kcal/mol.
In this, we establish a dynamics-based connection from GLUT3’s
crystal structure to its cellular thermodynamics with quantitative
accuracy. We predict equal Arrhenius barriers for glucose uptake and
efflux through GLUT3 to be tested in future experiments.
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Affiliation(s)
- Huiyun Liang
- Department of Physics, University of Texas at San Antonio, San Antonio, Texas 78249 United States
| | - Allen K. Bourdon
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Liao Y. Chen
- Department of Physics, University of Texas at San Antonio, San Antonio, Texas 78249 United States
| | - Clyde F. Phelix
- Department of Biology, University of Texas at San Antonio, San Antonio, Texas 78249 United States
| | - George Perry
- Department of Biology and Neurosciences Institute, University of Texas at San Antonio, San Antonio, Texas 78249, United States
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18
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Direct protein-lipid interactions shape the conformational landscape of secondary transporters. Nat Commun 2018; 9:4151. [PMID: 30297844 PMCID: PMC6175955 DOI: 10.1038/s41467-018-06704-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/19/2018] [Indexed: 12/31/2022] Open
Abstract
Secondary transporters undergo structural rearrangements to catalyze substrate translocation across the cell membrane – yet how such conformational changes happen within a lipid environment remains poorly understood. Here, we combine hydrogen-deuterium exchange mass spectrometry (HDX-MS) with molecular dynamics (MD) simulations to understand how lipids regulate the conformational dynamics of secondary transporters at the molecular level. Using the homologous transporters XylE, LacY and GlpT from Escherichia coli as model systems, we discover that conserved networks of charged residues act as molecular switches that drive the conformational transition between different states. We reveal that these molecular switches are regulated by interactions with surrounding phospholipids and show that phosphatidylethanolamine interferes with the formation of the conserved networks and favors an inward-facing state. Overall, this work provides insights into the importance of lipids in shaping the conformational landscape of an important class of transporters. Secondary transporters catalyse substrate translocation across the cell membrane but the role of lipids during the transport cycle remains unclear. Here authors used hydrogen-deuterium exchange mass spectrometry and molecular dynamics simulations to understand how lipids regulate the conformational dynamics of secondary transporters.
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Genetic Analysis of Signal Generation by the Rgt2 Glucose Sensor of Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2018; 8:2685-2696. [PMID: 29954842 PMCID: PMC6071613 DOI: 10.1534/g3.118.200338] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The yeast S. cerevisiae senses glucose through Snf3 and Rgt2, transmembrane proteins that generate an intracellular signal in response to glucose that leads to inhibition of the Rgt1 transcriptional repressor and consequently to derepression of HXT genes encoding glucose transporters. Snf3 and Rgt2 are thought to be glucose receptors because they are similar to glucose transporters. In contrast to glucose transporters, they have unusually long C-terminal tails that bind to Mth1 and Std1, paralogous proteins that regulate function of the Rgt1 transcription factor. We show that the C-terminal tail of Rgt2 is not responsible for its inability to transport glucose. To gain insight into how the glucose sensors generate an intracellular signal, we identified RGT2 mutations that cause constitutive signal generation. Most of the mutations alter evolutionarily-conserved amino acids in the transmembrane spanning regions of Rgt2 that are predicted to be involved in maintaining an outward-facing conformation or to be in the substrate binding site. Our analysis of these mutations suggests they cause Rgt2 to adopt inward-facing or occluded conformations that generate the glucose signal. These results support the idea that Rgt2 and Snf3 are glucose receptors that signal in response to binding of extracellular glucose and inform the basis of their signaling.
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20
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A Glimpse of Membrane Transport through Structures—Advances in the Structural Biology of the GLUT Glucose Transporters. J Mol Biol 2017; 429:2710-2725. [DOI: 10.1016/j.jmb.2017.07.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 07/13/2017] [Accepted: 07/15/2017] [Indexed: 01/17/2023]
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