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Fiamenghi MB, Bueno JGR, Camargo AP, Borelli G, Carazzolle MF, Pereira GAG, dos Santos LV, José J. Machine learning and comparative genomics approaches for the discovery of xylose transporters in yeast. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:57. [PMID: 35596177 PMCID: PMC9123741 DOI: 10.1186/s13068-022-02153-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/05/2022] [Indexed: 11/15/2022]
Abstract
Background The need to mitigate and substitute the use of fossil fuels as the main energy matrix has led to the study and development of biofuels as an alternative. Second-generation (2G) ethanol arises as one biofuel with great potential, due to not only maintaining food security, but also as a product from economically interesting crops such as energy-cane. One of the main challenges of 2G ethanol is the inefficient uptake of pentose sugars by industrial yeast Saccharomyces cerevisiae, the main organism used for ethanol production. Understanding the main drivers for xylose assimilation and identify novel and efficient transporters is a key step to make the 2G process economically viable. Results By implementing a strategy of searching for present motifs that may be responsible for xylose transport and past adaptations of sugar transporters in xylose fermenting species, we obtained a classifying model which was successfully used to select four different candidate transporters for evaluation in the S. cerevisiae hxt-null strain, EBY.VW4000, harbouring the xylose consumption pathway. Yeast cells expressing the transporters SpX, SpH and SpG showed a superior uptake performance in xylose compared to traditional literature control Gxf1. Conclusions Modelling xylose transport with the small data available for yeast and bacteria proved a challenge that was overcome through different statistical strategies. Through this strategy, we present four novel xylose transporters which expands the repertoire of candidates targeting yeast genetic engineering for industrial fermentation. The repeated use of the model for characterizing new transporters will be useful both into finding the best candidates for industrial utilization and to increase the model’s predictive capabilities. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13068-022-02153-7.
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Geng B, Jia X, Peng X, Han Y. Biosynthesis of value-added bioproducts from hemicellulose of biomass through microbial metabolic engineering. Metab Eng Commun 2022; 15:e00211. [PMID: 36311477 PMCID: PMC9597109 DOI: 10.1016/j.mec.2022.e00211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 10/02/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022] Open
Abstract
Hemicellulose is the second most abundant carbohydrate in lignocellulosic biomass and has extensive applications. In conventional biomass refinery, hemicellulose is easily converted to unwanted by-products in pretreatment and therefore can't be fully utilized. The present study aims to summarize the most recent development of lignocellulosic polysaccharide degradation and fully convert it to value-added bioproducts through microbial and enzymatic catalysis. Firstly, bioprocess and microbial metabolic engineering for enhanced utilization of lignocellulosic carbohydrates were discussed. The bioprocess for degradation and conversion of natural lignocellulose to monosaccharides and organic acids using anaerobic thermophilic bacteria and thermostable glycoside hydrolases were summarized. Xylose transmembrane transporting systems in natural microorganisms and the latest strategies for promoting the transporting capacity by metabolic engineering were summarized. The carbon catabolite repression effect restricting xylose utilization in microorganisms, and metabolic engineering strategies developed for co-utilization of glucose and xylose were discussed. Secondly, the metabolic pathways of xylose catabolism in microorganisms were comparatively analyzed. Microbial metabolic engineering for converting xylose to value-added bioproducts based on redox pathways, non-redox pathways, pentose phosphate pathway, and improving inhibitors resistance were summarized. Thirdly, strategies for degrading lignocellulosic polysaccharides and fully converting hemicellulose to value-added bioproducts through microbial metabolic engineering were proposed. Hemicellulose is the main carbohydrate of biomass and has valuable applications. Hemicellulose is underutilized in conventional biomass refinery and pretreatment. Microbial and enzymatic catalysis were applied for hemicellulose utilization. Xylose is converted to value-added bioproducts by metabolic engineering.
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Affiliation(s)
- Biao Geng
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China,School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaojing Jia
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China,School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaowei Peng
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China,School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yejun Han
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China,School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China,Corresponding author. National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China.
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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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Gonzalez-Resines S, Quinn PJ, Naftalin RJ, Domene C. Multiple Interactions of Glucose with the Extra-Membranous Loops of GLUT1 Aid Transport. J Chem Inf Model 2021; 61:3559-3570. [PMID: 34260246 DOI: 10.1021/acs.jcim.1c00310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Molecular dynamics simulations amounting to ≈8 μs demonstrate that the glucose transporter GLUT1 undergoes structural fluctuations mediated by the fluidity of the lipid bilayer and the proximity to glucose. The fluctuations of GLUT1 increase as the glucose concentration is raised. These fluctuations are more pronounced when the lipid bilayer is in the fluid compared to the gel phase. Glucose interactions are confined to the extra-membranous residues when the lipid is in the gel phase but diffuses into the transmembrane regions in the fluid phase. Proximity of glucose to GLUT1 causes asynchronous expansions of key bottlenecks at the internal and external openings of the central pore. This is accomplished only by small conformational changes at the single residue level that lower the resistance to glucose movements, thereby permitting unsteered glucose and water movements along the entire length of the pore. When glucose is near salt bridges located at the external and internal openings of the central pore, the distance separating the polar amino acid residues guarding these apertures tends to increase in both fluid and gel phases. It is evident that the multiplicity of glucose interactions, obtained with high concentrations, amplifies the structural fluctuations in GLUT1. The findings that most of the salt bridges and the bottlenecks appear to be operated by glucose proximity suggest that the main triggers to activation of transport are located within the solvent accessible linker regions in the extramembranous zones.
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Affiliation(s)
| | - Peter J Quinn
- Department of Biochemistry, King's College London, London WC2R 2LS, U.K
| | - Richard J Naftalin
- BHF Centre of Research Excellence, School of Medicine and Life Sciences, King's College London, London WC2R 2LS, U.K
| | - Carmen Domene
- Departments of Chemistry, University of Bath, Bath BA2 7AX, U.K.,Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
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5
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Decherchi S, Cavalli A. Thermodynamics and Kinetics of Drug-Target Binding by Molecular Simulation. Chem Rev 2020; 120:12788-12833. [PMID: 33006893 PMCID: PMC8011912 DOI: 10.1021/acs.chemrev.0c00534] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Indexed: 12/19/2022]
Abstract
Computational studies play an increasingly important role in chemistry and biophysics, mainly thanks to improvements in hardware and algorithms. In drug discovery and development, computational studies can reduce the costs and risks of bringing a new medicine to market. Computational simulations are mainly used to optimize promising new compounds by estimating their binding affinity to proteins. This is challenging due to the complexity of the simulated system. To assess the present and future value of simulation for drug discovery, we review key applications of advanced methods for sampling complex free-energy landscapes at near nonergodicity conditions and for estimating the rate coefficients of very slow processes of pharmacological interest. We outline the statistical mechanics and computational background behind this research, including methods such as steered molecular dynamics and metadynamics. We review recent applications to pharmacology and drug discovery and discuss possible guidelines for the practitioner. Recent trends in machine learning are also briefly discussed. Thanks to the rapid development of methods for characterizing and quantifying rare events, simulation's role in drug discovery is likely to expand, making it a valuable complement to experimental and clinical approaches.
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Affiliation(s)
- Sergio Decherchi
- Computational
and Chemical Biology, Fondazione Istituto
Italiano di Tecnologia, 16163 Genoa, Italy
| | - Andrea Cavalli
- Computational
and Chemical Biology, Fondazione Istituto
Italiano di Tecnologia, 16163 Genoa, Italy
- Department
of Pharmacy and Biotechnology, University
of Bologna, 40126 Bologna, Italy
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6
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Wu Z, Alibay I, Newstead S, Biggin PC. Proton Control of Transitions in an Amino Acid Transporter. Biophys J 2019; 117:1342-1351. [PMID: 31500802 PMCID: PMC6818167 DOI: 10.1016/j.bpj.2019.07.056] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 07/03/2019] [Accepted: 07/30/2019] [Indexed: 12/19/2022] Open
Abstract
Amino acid transport into the cell is often coupled to the proton electrochemical gradient, as found in the solute carrier 36 family of proton-coupled amino acid transporters. Although no structure of a human proton-coupled amino acid transporter exists, the crystal structure of a related homolog from bacteria, GkApcT, has recently been solved in an inward-occluded state and allows an opportunity to examine how protons are coupled to amino acid transport. Our working hypothesis is that release of the amino acid substrate is facilitated by the deprotonation of a key glutamate residue (E115) located at the bottom of the binding pocket, which forms part of the intracellular gate, allowing the protein to transition from an inward-occluded to an inward-open conformation. During unbiased molecular dynamics simulations, we observed a transition from the inward-occluded state captured in the crystal structure to a much more open state, which we consider likely to be representative of the inward-open state associated with substrate release. To explore this and the role of protons in these transitions, we have used umbrella sampling to demonstrate that the transition from inward occluded to inward open is more energetically favorable when E115 is deprotonated. That E115 is likely to be protonated in the inward-occluded state and deprotonated in the inward-open state is further confirmed via the use of absolute binding free energies. Finally, we also show, via the use of absolute binding free energy calculations, that the affinity of the protein for alanine is very similar regardless of either the conformational state or the protonation of E115, presumably reflecting the fact that all the key interactions are deep within the binding cavity. Together, our results give a detailed picture of the role of protons in driving one of the major transitions in this transporter.
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Affiliation(s)
- Zhiyi Wu
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Irfan Alibay
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Philip C Biggin
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
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7
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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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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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