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Tai Y, Zhang Z, Liu Z, Li X, Yang Z, Wang Z, An L, Ma Q, Su Y. D-ribose metabolic disorder and diabetes mellitus. Mol Biol Rep 2024; 51:220. [PMID: 38281218 PMCID: PMC10822815 DOI: 10.1007/s11033-023-09076-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 11/21/2023] [Indexed: 01/30/2024]
Abstract
D-ribose, an ubiquitous pentose compound found in all living cells, serves as a vital constituent of numerous essential biomolecules, including RNA, nucleotides, and riboflavin. It plays a crucial role in various fundamental life processes. Within the cellular milieu, exogenously supplied D-ribose can undergo phosphorylation to yield ribose-5-phosphate (R-5-P). This R-5-P compound serves a dual purpose: it not only contributes to adenosine triphosphate (ATP) production through the nonoxidative phase of the pentose phosphate pathway (PPP) but also participates in nucleotide synthesis. Consequently, D-ribose is employed both as a therapeutic agent for enhancing cardiac function in heart failure patients and as a remedy for post-exercise fatigue. Nevertheless, recent clinical studies have suggested a potential link between D-ribose metabolic disturbances and type 2 diabetes mellitus (T2DM) along with its associated complications. Additionally, certain in vitro experiments have indicated that exogenous D-ribose exposure could trigger apoptosis in specific cell lines. This article comprehensively reviews the current advancements in D-ribose's digestion, absorption, transmembrane transport, intracellular metabolic pathways, impact on cellular behaviour, and elevated levels in diabetes mellitus. It also identifies areas requiring further investigation.
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Affiliation(s)
- Yu Tai
- Institute of Biochemistry and Molecular Biology, Baotou Medical College, Baotou, Inner Mongolia, China
| | - Zehong Zhang
- Institute of Biochemistry and Molecular Biology, Baotou Medical College, Baotou, Inner Mongolia, China
- Department of Clinical Laboratory, the Fourth Hospital of Baotou, Baotou, Inner Mongolia, China
| | - Zhi Liu
- Institute of Biochemistry and Molecular Biology, Baotou Medical College, Baotou, Inner Mongolia, China
| | - Xiaojing Li
- Institute of Biochemistry and Molecular Biology, Baotou Medical College, Baotou, Inner Mongolia, China
| | - Zhongbin Yang
- Institute of Biochemistry and Molecular Biology, Baotou Medical College, Baotou, Inner Mongolia, China
| | - Zeying Wang
- Institute of Biochemistry and Molecular Biology, Baotou Medical College, Baotou, Inner Mongolia, China
| | - Liang An
- Department of Clinical Laboratory, the Fourth Hospital of Baotou, Baotou, Inner Mongolia, China
| | - Qiang Ma
- Institute of Biochemistry and Molecular Biology, Baotou Medical College, Baotou, Inner Mongolia, China
| | - Yan Su
- Institute of Biochemistry and Molecular Biology, Baotou Medical College, Baotou, Inner Mongolia, China.
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Garcia-Gil M, Camici M, Allegrini S, Pesi R, Tozzi MG. Metabolic Aspects of Adenosine Functions in the Brain. Front Pharmacol 2021; 12:672182. [PMID: 34054547 PMCID: PMC8160517 DOI: 10.3389/fphar.2021.672182] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 04/27/2021] [Indexed: 12/13/2022] Open
Abstract
Adenosine, acting both through G-protein coupled adenosine receptors and intracellularly, plays a complex role in multiple physiological and pathophysiological processes by modulating neuronal plasticity, astrocytic activity, learning and memory, motor function, feeding, control of sleep and aging. Adenosine is involved in stroke, epilepsy and neurodegenerative pathologies. Extracellular concentration of adenosine in the brain is tightly regulated. Adenosine may be generated intracellularly in the central nervous system from degradation of AMP or from the hydrolysis of S-adenosyl homocysteine, and then exit via bi-directional nucleoside transporters, or extracellularly by the metabolism of released nucleotides. Inactivation of extracellular adenosine occurs by transport into neurons or neighboring cells, followed by either phosphorylation to AMP by adenosine kinase or deamination to inosine by adenosine deaminase. Modulation of the nucleoside transporters or of the enzymatic activities involved in the metabolism of adenosine, by affecting the levels of this nucleoside and the activity of adenosine receptors, could have a role in the onset or the development of central nervous system disorders, and can also be target of drugs for their treatment. In this review, we focus on the contribution of 5'-nucleotidases, adenosine kinase, adenosine deaminase, AMP deaminase, AMP-activated protein kinase and nucleoside transporters in epilepsy, cognition, and neurodegenerative diseases with a particular attention on amyotrophic lateral sclerosis and Huntington's disease. We include several examples of the involvement of components of the adenosine metabolism in learning and of the possible use of modulators of enzymes involved in adenosine metabolism or nucleoside transporters in the amelioration of cognition deficits.
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Affiliation(s)
- Mercedes Garcia-Gil
- Department of Biology, Unit of Physiology, University of Pisa, Pisa, Italy.,Interdepartmental Research Center "Nutraceuticals and Food for Health", University of Pisa, Pisa, Italy
| | - Marcella Camici
- Department of Biology, Unit of Biochemistry, University of Pisa, Pisa, Italy
| | - Simone Allegrini
- Department of Biology, Unit of Biochemistry, University of Pisa, Pisa, Italy
| | - Rossana Pesi
- Department of Biology, Unit of Biochemistry, University of Pisa, Pisa, Italy
| | - Maria Grazia Tozzi
- Department of Biology, Unit of Biochemistry, University of Pisa, Pisa, Italy
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Ahmed MS, Lauersen KJ, Ikram S, Li C. Efflux Transporters' Engineering and Their Application in Microbial Production of Heterologous Metabolites. ACS Synth Biol 2021; 10:646-669. [PMID: 33751883 DOI: 10.1021/acssynbio.0c00507] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Metabolic engineering of microbial hosts for the production of heterologous metabolites and biochemicals is an enabling technology to generate meaningful quantities of desired products that may be otherwise difficult to produce by traditional means. Heterologous metabolite production can be restricted by the accumulation of toxic products within the cell. Efflux transport proteins (transporters) provide a potential solution to facilitate the export of these products, mitigate toxic effects, and enhance production. Recent investigations using knockout lines, heterologous expression, and expression profiling of transporters have revealed candidates that can enhance the export of heterologous metabolites from microbial cell systems. Transporter engineering efforts have revealed that some exhibit flexible substrate specificity and may have broader application potentials. In this Review, the major superfamilies of efflux transporters, their mechanistic modes of action, selection of appropriate efflux transporters for desired compounds, and potential transporter engineering strategies are described for potential applications in enhancing engineered microbial metabolite production. Future studies in substrate recognition, heterologous expression, and combinatorial engineering of efflux transporters will assist efforts to enhance heterologous metabolite production in microbial hosts.
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Affiliation(s)
- Muhammad Saad Ahmed
- Institute for Synthetic Biosystem/Department of Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology (BIT), Beijing 100081, P. R. China
- Department of Biological Sciences, National University of Medical Sciences (NUMS), Abid Majeed Road, The Mall, Rawalpindi 46000, Pakistan
| | - Kyle J. Lauersen
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Kingdom of Saudi Arabia
| | - Sana Ikram
- Beijing Higher Institution Engineering Research Center for Food Additives and Ingredients, Beijing Technology & Business University (BTBU), Beijing 100048, P. R. China
| | - Chun Li
- Institute for Synthetic Biosystem/Department of Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology (BIT), Beijing 100081, P. R. China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, P. R. China
- Key Laboratory for Industrial Biocatalysis, Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
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Gatreddi S, Pillalamarri V, Vasudevan D, Addlagatta A, Qureshi IA. Unraveling structural insights of ribokinase from Leishmania donovani. Int J Biol Macromol 2019; 136:253-265. [PMID: 31170491 DOI: 10.1016/j.ijbiomac.2019.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/29/2019] [Accepted: 06/01/2019] [Indexed: 11/16/2022]
Abstract
Ribokinase (RK) is an ATP dependent sugar kinase that enables the entry of ribose in the metabolism. Leishmania accumulates ribose into the cytosol through hydrolysis of nucleosides and by transport from the extracellular environment. Activation by RK is critical to mobilize the ribose into the metabolism of Leishmania. To understand the catalytic role, the crystal structure of RK (LdRK) from L. donovani was determined in the apo and complex forms with several nucleotides (ATP, AMPPCP and ADP) in the presence of Na+ ion. The dual insertion of five amino acid stretches makes LdRK structurally unique from other reported structures of RKs. The structure of LdRK-ATP provided the basis for positioning of γ-phosphate of ATP by conserved -GAGD- motif. Liganded and unliganded structures of LdRK exists in similar conformation, which suggests binding of nucleotides does not make any significant conformational changes in nucleotide-bound structures. Substitution of a conserved asparagine with phenylalanine in ribose binding pocket differentiates the LdRK from other RKs. Glycerol molecule bound in the substrate binding pocket mimics the enzyme-substrate interactions but in turn, hampers the binding of ribose to LdRK. Comparative structural analysis revealed the flexibility of γ-phosphate, which adopts multiple conformations in the absence of divalent metal ion and ribose. Similar to other RKs, LdRK is also dependent on monovalent as well as divalent cations for its catalytic activity.
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Affiliation(s)
- Santhosh Gatreddi
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, Telangana, India
| | - Vijaykumar Pillalamarri
- CSIR-Indian Institute of Chemical Technology, Applied Biology, Hyderabad 500 007, Telangana, India; Academy of Scientific and Innovative Research (AcSIR), Rafi Marg, New Delhi 110001, India
| | | | - Anthony Addlagatta
- CSIR-Indian Institute of Chemical Technology, Applied Biology, Hyderabad 500 007, Telangana, India; Academy of Scientific and Innovative Research (AcSIR), Rafi Marg, New Delhi 110001, India
| | - Insaf Ahmed Qureshi
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, Telangana, India.
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Gatreddi S, Are S, Qureshi IA. Ribokinase from Leishmania donovani: purification, characterization and X-ray crystallographic analysis. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2018; 74:99-104. [PMID: 29400319 DOI: 10.1107/s2053230x18000109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/02/2018] [Indexed: 11/11/2022]
Abstract
Leishmania is an auxotrophic protozoan parasite which acquires D-ribose by transporting it from the host cell and also by the hydrolysis of nucleosides. The enzyme ribokinase (RK) catalyzes the first step of ribose metabolism by phosphorylating D-ribose using ATP to produce D-ribose-5-phosphate. To understand its structure and function, the gene encoding RK from L. donovani was cloned, expressed and purified using affinity and size-exclusion chromatography. Circular-dichroism spectroscopy of the purified protein showed comparatively more α-helix in the secondary-structure content, and thermal unfolding revealed the Tm to be 317.2 K. Kinetic parameters were obtained by functional characterization of L. donovani RK, and the Km values for ribose and ATP were found to be 296 ± 36 and 116 ± 9.0 µM, respectively. Crystals obtained by the hanging-drop vapour-diffusion method diffracted to 1.95 Å resolution and belonged to the hexagonal space group P61, with unit-cell parameters a = b = 100.25, c = 126.77 Å. Analysis of the crystal content indicated the presence of two protomers in the asymmetric unit, with a Matthews coefficient (VM) of 2.45 Å3 Da-1 and 49.8% solvent content. Further study revealed that human counterpart of this protein could be used as a template to determine the first three-dimensional structure of the RK from trypanosomatid parasites.
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Affiliation(s)
- Santhosh Gatreddi
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Professor C. R. Rao Road, Hyderabad 500 046, India
| | - Sayanna Are
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Professor C. R. Rao Road, Hyderabad 500 046, India
| | - Insaf Ahmed Qureshi
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Professor C. R. Rao Road, Hyderabad 500 046, India
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Vara D, Watt JM, Fortunato TM, Mellor H, Burgess M, Wicks K, Mace K, Reeksting S, Lubben A, Wheeler-Jones CPD, Pula G. Direct Activation of NADPH Oxidase 2 by 2-Deoxyribose-1-Phosphate Triggers Nuclear Factor Kappa B-Dependent Angiogenesis. Antioxid Redox Signal 2018; 28:110-130. [PMID: 28793782 PMCID: PMC5725637 DOI: 10.1089/ars.2016.6869] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AIMS Deoxyribose-1-phosphate (dRP) is a proangiogenic paracrine stimulus released by cancer cells, platelets, and macrophages and acting on endothelial cells. The objective of this study was to clarify how dRP stimulates angiogenic responses in human endothelial cells. RESULTS Live cell imaging, electron paramagnetic resonance, pull-down of dRP-interacting proteins, followed by immunoblotting, gene silencing of different NADPH oxidases (NOXs), and their regulatory cosubunits by small interfering RNA (siRNA) transfection, and experiments with inhibitors of the sugar transporter glucose transporter 1 (GLUT1) were utilized to demonstrate that dRP acts intracellularly by directly activating the endothelial NOX2 complex, but not NOX4. Increased reactive oxygen species generation in response to NOX2 activity leads to redox-dependent activation of the transcription factor nuclear factor kappa B (NF-κB), which, in turn, induces vascular endothelial growth factor receptor 2 (VEGFR2) upregulation. Using endothelial tube formation assays, gene silencing by siRNA, and antibody-based receptor inhibition, we demonstrate that the activation of NF-κB and VEGFR2 is necessary for the angiogenic responses elicited by dRP. The upregulation of VEGFR2 and NOX2-dependent stimulation of angiogenesis by dRP were confirmed in excisional wound and Matrigel plug vascularization assays in vivo using NOX2-/- mice. INNOVATION For the first time, we demonstrate that dRP acts intracellularly and stimulates superoxide anion generation by direct binding and activation of the NOX2 enzymatic complex. CONCLUSIONS This study describes a novel molecular mechanism underlying the proangiogenic activity of dRP, which involves the sequential activation of NOX2 and NF-κB and upregulation of VEGFR2. Antioxid. Redox Signal. 28, 110-130.
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Affiliation(s)
- Dina Vara
- 1 Institute of Biomedical and Clinical Science, University of Exeter Medical School , Exeter, United Kingdom
| | - Joanna M Watt
- 2 Department of Pharmacy and Pharmacology, University of Bath , Bath, United Kingdom
| | - Tiago M Fortunato
- 3 Department of Biomedical Engineering, Eindhoven University of Technology , Eindhoven, The Netherlands
| | - Harry Mellor
- 4 Department of Biochemistry, University of Bristol , Bristol, United Kingdom
| | - Matthew Burgess
- 5 The Healing Foundation Centre, University of Manchester , Manchester, United Kingdom
| | - Kate Wicks
- 5 The Healing Foundation Centre, University of Manchester , Manchester, United Kingdom
| | - Kimberly Mace
- 5 The Healing Foundation Centre, University of Manchester , Manchester, United Kingdom
| | - Shaun Reeksting
- 6 Mass Spectrometry Service and Chemical Characterisation and Analysis Facility, University of Bath , Bath, United Kingdom
| | - Anneke Lubben
- 6 Mass Spectrometry Service and Chemical Characterisation and Analysis Facility, University of Bath , Bath, United Kingdom
| | | | - Giordano Pula
- 1 Institute of Biomedical and Clinical Science, University of Exeter Medical School , Exeter, United Kingdom
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7
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The role of membrane transporters in Leishmania virulence. Emerg Top Life Sci 2017; 1:601-611. [DOI: 10.1042/etls20170119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/19/2017] [Accepted: 11/23/2017] [Indexed: 11/17/2022]
Abstract
Leishmania are parasitic protozoa which infect humans and cause severe morbidity and mortality. Leishmania parasitise as extracellular promastigotes in the insect vector and as intracellular amastigotes in the mammalian host. Cycling between hosts involves implementation of stringent and co-ordinated responses to shifting environmental conditions. One of the key dynamic aspects of Leishmania biology is substrate acquisition and metabolism. Genomic analyses have revealed that Leishmania encode many putative membrane transporters, many of which are differentially expressed during the parasite life cycle. Only a small fraction of these transporters, however, have been functionally characterised. Currently, most information is available about nutrient transporters, mainly involved in carbohydrate, amino acid, nucleobase and nucleoside, cofactor, and ion acquisition. Several have apparent roles in Leishmania virulence and will be discussed in this perspective.
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Akpunarlieva S, Weidt S, Lamasudin D, Naula C, Henderson D, Barrett M, Burgess K, Burchmore R. Integration of proteomics and metabolomics to elucidate metabolic adaptation in Leishmania. J Proteomics 2017; 155:85-98. [DOI: 10.1016/j.jprot.2016.12.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/13/2016] [Accepted: 12/16/2016] [Indexed: 01/16/2023]
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Kim KS, Kim SH. Effect of N-(D-Ribopyranosyl) Taurine Sodium Salt on the Differentiation of Human Preadipocytes and Expression of Adipokines Through Inhibition of STAT-3 Signaling in Differentiated Human Adipocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 975:667-674. [PMID: 28849490 DOI: 10.1007/978-94-024-1079-2_52] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We investigated whether a taurine-ribose derivative, N-(D-ribopyranosyl)taurine sodium salt, inhibits the differentiation process of preadipocytes or modulates the expression of cytokines from adipocytes as does taurine chloramine (TauCl) in vitro. To know the inhibitory effects of taurine-ribose (Tau-Ribose) on differentiation process and adipokine expression, preadipocytes were incubated with Tau-Ribose in differentiation medium for 14 days. Differentiated adipocytes were also stimulated at the concentration of IL-1β 1 ng/ml with addition of Tau-Ribose. After 7 days of incubation, the levels of adiponectin, leptin, IL-6, and IL-8 were measured from the culture supernatants. At concentrations of 10-40 mM, Tau-Ribose dose-dependently inhibited the process of adipogenesis. The treatment of Tau-Ribose decreased the expression of transcription factors, which are necessary for adipogenesis and are known as adipocyte marker. Treatment with Tau-Ribose significantly modulated the production of IL-8 and IL-6. However, it did not modulate the production of adiponectin and leptin in IL-1β-activated adipocytes. As with taurine chloramine, Tau-Ribose also inhibited STAT-3 signaling, independent of MAPK signaling. In conclusion, Tau-Ribose inhibits the signaling pathway of STAT-3 and can change adipokines production; thus, it may have a potential as an agent for treating obesity-related diseases.
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Affiliation(s)
- Kyoung-Soo Kim
- East-West Bone and Joint Disease Research Institute, Kyung Hee University Hospital at Gangdong, 149 Sangil-dong, Gandong-gu, Seoul, South Korea.
- Department of Clinical Pharmacology and Therapeutics, College of Medicine, Kyung Hee University, Seoul, South Korea.
| | - Sung Hoon Kim
- Department of Chemistry, Konkuk University, Seoul, 143-701, South Korea
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Faria J, Loureiro I, Santarém N, Cecílio P, Macedo-Ribeiro S, Tavares J, Cordeiro-da-Silva A. Disclosing the essentiality of ribose-5-phosphate isomerase B in Trypanosomatids. Sci Rep 2016; 6:26937. [PMID: 27230471 PMCID: PMC4882579 DOI: 10.1038/srep26937] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 05/10/2016] [Indexed: 01/31/2023] Open
Abstract
Ribose-5-phosphate isomerase (RPI) belongs to the non-oxidative branch of the pentose phosphate pathway, catalysing the inter-conversion of D-ribose-5-phosphate and D-ribulose-5-phosphate. Trypanosomatids encode a type B RPI, whereas humans have a structurally unrelated type A, making RPIB worthy of exploration as a potential drug target. Null mutant generation in Leishmania infantum was only possible when an episomal copy of RPIB gene was provided, and the latter was retained both in vitro and in vivo in the absence of drug pressure. This suggests the gene is essential for parasite survival. Importantly, the inability to remove the second allele of RPIB gene in sKO mutants complemented with an episomal copy of RPIB carrying a mutation that abolishes isomerase activity suggests the essentiality is due to its metabolic function. In vitro, sKO promastigotes exhibited no defect in growth, metacyclogenesis or macrophage infection, however, an impairment in intracellular amastigotes' replication was observed. Additionally, mice infected with sKO mutants rescued by RPIB complementation had a reduced parasite burden in the liver. Likewise, Trypanosoma brucei is resistant to complete RPIB gene removal and mice infected with sKO mutants showed prolonged survival upon infection. Taken together our results genetically validate RPIB as a potential drug target in trypanosomatids.
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Affiliation(s)
- Joana Faria
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Inês Loureiro
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Nuno Santarém
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Pedro Cecílio
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Sandra Macedo-Ribeiro
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Protein Crystallography Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Portugal
| | - Joana Tavares
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Anabela Cordeiro-da-Silva
- Parasite Disease Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Portugal
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Fonseca ALD, Nunes RR, Braga VML, Comar M, Alves RJ, Varotti FDP, Taranto AG. Docking, QM/MM, and molecular dynamics simulations of the hexose transporter from Plasmodium falciparum (PfHT). J Mol Graph Model 2016; 66:174-86. [PMID: 27131282 DOI: 10.1016/j.jmgm.2016.03.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 03/14/2016] [Accepted: 03/24/2016] [Indexed: 01/19/2023]
Abstract
Malaria is the most prevalent parasitic disease in the world. Currently, an effective vaccine for malaria does not exist, and chemotherapy must be used to treat the disease. Because of increasing resistance to current antimalarial drugs, new treatments must be developed. Among the many potential molecular targets, the hexose transporter of Plasmodium falciparum (PfHT) is particularly promising because it plays a vital role in glucose transport for the parasite. Thus, this study aims to determine the three-dimensional structure of PfHT and to describe the intermolecular interactions between active glycoside derivatives and PfHT. Such information should aid in the development of new antimalarial drugs. The receptor PfHT was constructed from primary sequences deposited in the SWISS MODEL database. Next, molecular docking simulations between O-(undec-10-en)-l-D-glucose and the constructed active site models were performed using Autodock Vina. The glycoside derivative-PfHT complexes were then refined using the hybrid QM/MM (PM3/ff03) method within the AMBER package. The models were then evaluated using Ramachandran plots, which indicated that 93.2% of the residues in the refined PfHT models (P5) were present in favorable regions. Furthermore, graphical plots using ANOLEA showed that the potential energies of interaction for atoms unbonded to P5 were negative. Finally, the O-(undec-10-en)-l-D-glucose-PfHT complex was evaluated using 20-ns Molecular Dynamics simulations with an ff03 force field. Docking and QM/MM studies revealed the amino acids essential for molecular recognition of and activity on glycosides. Inhibition of glucose transporters may prevent the development and metabolism of P. falciparum, so a description of the receptor's structure is a critical step towards rational drug design.
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Affiliation(s)
- Amanda Luisa da Fonseca
- Núcleo de Pesquisa em Química Biológica, Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil; Laboratório de Modelagem Molecular, Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil; Laboratório de Química Medicinal Farmacêutica, Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil
| | - Renata Rachide Nunes
- Laboratório de Química Medicinal Farmacêutica, Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil
| | - Vanildo Martins Lima Braga
- Laboratório de Química Medicinal Farmacêutica, Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil
| | - Moacyr Comar
- Laboratório de Modelagem Molecular, Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil
| | - Ricardo José Alves
- Laboratório de Química, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Fernando de Pilla Varotti
- Núcleo de Pesquisa em Química Biológica, Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil
| | - Alex Gutterres Taranto
- Laboratório de Química Medicinal Farmacêutica, Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil.
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12
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Gebril HM, Avula B, Wang YH, Khan IA, Jekabsons MB. (13)C metabolic flux analysis in neurons utilizing a model that accounts for hexose phosphate recycling within the pentose phosphate pathway. Neurochem Int 2015; 93:26-39. [PMID: 26723542 DOI: 10.1016/j.neuint.2015.12.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 12/16/2015] [Accepted: 12/18/2015] [Indexed: 11/25/2022]
Abstract
Glycolysis, mitochondrial substrate oxidation, and the pentose phosphate pathway (PPP) are critical for neuronal bioenergetics and oxidation-reduction homeostasis, but quantitating their fluxes remains challenging, especially when processes such as hexose phosphate (i.e., glucose/fructose-6-phosphate) recycling in the PPP are considered. A hexose phosphate recycling model was developed which exploited the rates of glucose consumption, lactate production, and mitochondrial respiration to infer fluxes through the major glucose consuming pathways of adherent cerebellar granule neurons by replicating [(13)C]lactate labeling from metabolism of [1,2-(13)C2]glucose. Flux calculations were predicated on a steady-state system with reactions having known stoichiometries and carbon atom transitions. Non-oxidative PPP activity and consequent hexose phosphate recycling, as well as pyruvate production by cytoplasmic malic enzyme, were optimized by the model and found to account for 28 ± 2% and 7.7 ± 0.2% of hexose phosphate and pyruvate labeling, respectively. From the resulting fluxes, 52 ± 6% of glucose was metabolized by glycolysis, compared to 19 ± 2% by the combined oxidative/non-oxidative pentose cycle that allows for hexose phosphate recycling, and 29 ± 8% by the combined oxidative PPP/de novo nucleotide synthesis reactions. By extension, 62 ± 6% of glucose was converted to pyruvate, the metabolism of which resulted in 16 ± 1% of glucose oxidized by mitochondria and 46 ± 6% exported as lactate. The results indicate a surprisingly high proportion of glucose utilized by the pentose cycle and the reactions synthesizing nucleotides, and exported as lactate. While the in vitro conditions to which the neurons were exposed (high glucose, no lactate or other exogenous substrates) limit extrapolating these results to the in vivo state, the approach provides a means of assessing a number of metabolic fluxes within the context of hexose phosphate recycling in the PPP from a minimal set of measurements.
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Affiliation(s)
- Hoda M Gebril
- Department of Biology, Shoemaker Hall, University of Mississippi, University, MS 38677, USA.
| | - Bharathi Avula
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA.
| | - Yan-Hong Wang
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA.
| | - Ikhlas A Khan
- Department of Biomedical Sciences and National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA.
| | - Mika B Jekabsons
- Department of Biology, Shoemaker Hall, University of Mississippi, University, MS 38677, USA.
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13
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Dean P, Major P, Nakjang S, Hirt RP, Embley TM. Transport proteins of parasitic protists and their role in nutrient salvage. FRONTIERS IN PLANT SCIENCE 2014; 5:153. [PMID: 24808897 PMCID: PMC4010794 DOI: 10.3389/fpls.2014.00153] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Accepted: 04/01/2014] [Indexed: 05/02/2023]
Abstract
The loss of key biosynthetic pathways is a common feature of important parasitic protists, making them heavily dependent on scavenging nutrients from their hosts. This is often mediated by specialized transporter proteins that ensure the nutritional requirements of the parasite are met. Over the past decade, the completion of several parasite genome projects has facilitated the identification of parasite transporter proteins. This has been complemented by functional characterization of individual transporters along with investigations into their importance for parasite survival. In this review, we summarize the current knowledge on transporters from parasitic protists and highlight commonalities and differences in the transporter repertoires of different parasitic species, with particular focus on characterized transporters that act at the host-pathogen interface.
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Affiliation(s)
- Paul Dean
- *Correspondence: Paul Dean and T. Martin Embley, The Medical School, Institute for Cell and Molecular Biosciences, Newcastle University, Catherine Cookson Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK e-mail: ;
| | | | | | | | - T. Martin Embley
- *Correspondence: Paul Dean and T. Martin Embley, The Medical School, Institute for Cell and Molecular Biosciences, Newcastle University, Catherine Cookson Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK e-mail: ;
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14
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Wu T, Bound MJ, Zhao BR, Standfield SD, Bellon M, Jones KL, Horowitz M, Rayner CK. Effects of a D-xylose preload with or without sitagliptin on gastric emptying, glucagon-like peptide-1, and postprandial glycemia in type 2 diabetes. Diabetes Care 2013; 36:1913-8. [PMID: 23359361 PMCID: PMC3687261 DOI: 10.2337/dc12-2294] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Macronutrient "preloads" can reduce postprandial glycemia by slowing gastric emptying and stimulating glucagon-like peptide-1 (GLP-1) secretion. An ideal preload would entail minimal additional energy intake and might be optimized by concurrent inhibition of dipeptidyl peptidase-4 (DPP-4). We evaluated the effects of a low-energy D-xylose preload, with or without sitagliptin, on gastric emptying, plasma intact GLP-1 concentrations, and postprandial glycemia in type 2 diabetes. RESEARCH DESIGN AND METHODS Twelve type 2 diabetic patients were studied on four occasions each. After 100 mg sitagliptin (S) or placebo (P) and an overnight fast, patients consumed a preload drink containing either 50 g D-xylose (X) or 80 mg sucralose (control [C]), followed after 40 min by a mashed potato meal labeled with (13)C-octanoate. Blood was sampled at intervals. Gastric emptying was determined. RESULTS Both peak blood glucose and the amplitude of glycemic excursion were lower after PX and SC than PC (P < 0.01 for each) and were lowest after SX (P < 0.05 for each), while overall blood glucose was lower after SX than PC (P < 0.05). The postprandial insulin-to-glucose ratio was attenuated (P < 0.05) and gastric emptying was slower (P < 0.01) after D-xylose, without any effect of sitagliptin. Plasma GLP-1 concentrations were higher after D-xylose than control only before the meal (P < 0.05) but were sustained postprandially when combined with sitagliptin (P < 0.05). CONCLUSIONS In type 2 diabetes, acute administration of a D-xylose preload reduces postprandial glycemia and enhances the effect of a DPP-4 inhibitor.
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Affiliation(s)
- Tongzhi Wu
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Michelle J. Bound
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Beiyi R. Zhao
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Scott D. Standfield
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Max Bellon
- Department of Nuclear Medicine, Royal Adelaide Hospital, Adelaide, Australia
| | - Karen L. Jones
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Michael Horowitz
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Christopher K. Rayner
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
- Corresponding author: Chris K. Rayner,
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15
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Cunningham P, Naftalin RJ. Implications of aberrant temperature-sensitive glucose transport via the glucose transporter deficiency mutant (GLUT1DS) T295M for the alternate-access and fixed-site transport models. J Membr Biol 2013; 246:495-511. [PMID: 23740044 DOI: 10.1007/s00232-013-9564-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 05/15/2013] [Indexed: 12/27/2022]
Abstract
In silico glucose docking to the transporter GLUT1 templated to the crystal structure of Escherichia coli XylE, a bacterial homolog of GLUT1-4 (4GBZ.pdb), reveals multiple docking sites. One site in the external vestibule in the exofacial linker between TM7 and -8 is adjacent to a missense T295M and a 4-mer insertion mutation. Glucose docking to the adjacent site is occluded in these mutants. These mutants cause an atypical form of glucose transport deficiency syndrome (GLUT1DS), where transport into the brain is deficient, although unusually transport into erythrocytes at 4 °C appears normal. A model in which glucose traverses the transporter via a network of saturable fixed sites simulates the temperature sensitivity of normal and mutant glucose influx and the mutation-dependent alterations of influx and efflux asymmetry when expressed in Xenopus oocytes at 37 °C. The explanation for the temperature sensitivity is that at 4 °C glucose influx between the external and internal vestibules is slow and causes glucose to accumulate in the external vestibule. This retards net glucose uptake from the external solution via two parallel sites into the external vestibule, consequently masking any transport defect at either one of these sites. At 37 °C glucose transit between the external and internal vestibules is rapid, with no significant glucose buildup in the external vestibule, and thereby unmasks any transport defect at one of the parallel input sites. Monitoring glucose transport in patients' erythrocytes at higher temperatures may improve the diagnostic accuracy of the functional test of GLUT1DS.
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Affiliation(s)
- Philip Cunningham
- Bioinformatics Division, School of Medicine, King's College London, Franklin-Wilkins Building, Waterloo Campus, London SE1 9HN, UK
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16
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Dall'Angelo S, Bandaranayaka N, Windhorst AD, Vugts DJ, van der Born D, Onega M, Schweiger LF, Zanda M, O'Hagan D. Tumour imaging by Positron Emission Tomography using fluorinase generated 5-[18F]fluoro-5-deoxyribose as a novel tracer. Nucl Med Biol 2013; 40:464-70. [DOI: 10.1016/j.nucmedbio.2013.02.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 02/08/2013] [Accepted: 02/13/2013] [Indexed: 11/29/2022]
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17
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Feng X, Rodriguez-Contreras D, Polley T, Lye LF, Scott D, Burchmore RJS, Beverley SM, Landfear SM. 'Transient' genetic suppression facilitates generation of hexose transporter null mutants in Leishmania mexicana. Mol Microbiol 2012; 87:412-29. [PMID: 23170981 DOI: 10.1111/mmi.12106] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2012] [Indexed: 11/26/2022]
Abstract
The genome of Leishmania mexicana encompasses a cluster of three glucose transporter genes designated LmxGT1, LmxGT2 and LmxGT3. Functional and genetic studies of a cluster null mutant (Δlmxgt1-3) have dissected the roles of these proteins in Leishmania metabolism and virulence. However, null mutants were recovered at very low frequency, and comparative genome hybridizations revealed that Δlmxgt1-3 mutants contained a linear extrachromosomal 40 kb amplification of a region on chromosome 29 not amplified in wild type parasites. These data suggested a model where this 29-40k amplicon encoded a second site suppressor contributing to parasite survival in the absence of GT1-3 function. To test this, we quantified the frequency of recovery of knockouts in the presence of individual overexpressed open reading frames covering the 29-40k amplicon. The data mapped the suppressor activity to PIFTC3, encoding a component of the intraflagellar transport pathway. We discuss possible models by which PIFTC3 might act to facilitate loss of GTs specifically. Surprisingly, by plasmid segregation we showed that continued PIFTC3 overexpression was not required for Δlmxgt1-3 viability. These studies provide the first evidence that genetic suppression can occur by providing critical biological functions transiently. This novel form of genetic suppression may extend to other genes, pathways and organisms.
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Affiliation(s)
- Xiuhong Feng
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR 97239, USA
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18
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Lopez-de Los Santos Y, Chan H, Cantu VA, Rettner R, Sanchez F, Zhang Z, Saier MH, Soberon X. Genetic engineering of the phosphocarrier protein NPr of the Escherichia coli phosphotransferase system selectively improves sugar uptake activity. J Biol Chem 2012; 287:29931-9. [PMID: 22767600 DOI: 10.1074/jbc.m112.345660] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system (PTS) in prokaryotes mediates the uptake and phosphorylation of its numerous substrates through a phosphoryl transfer chain where a phosphoryl transfer protein, HPr, transfers its phosphoryl group to any of several sugar-specific Enzyme IIA proteins in preparation for sugar transport. A phosphoryl transfer protein of the PTS, NPr, homologous to HPr, functions to regulate nitrogen metabolism and shows virtually no enzymatic cross-reactivity with HPr. Here we describe the genetic engineering of a "chimeric" HPr/NPr protein, termed CPr14 because 14 amino acid residues of the interface were replaced. CPr14 shows decreased activity with most PTS permeases relative to HPr, but increases activity with the broad specificity mannose permease. The results lead to the proposal that HPr is not optimal for most PTS permeases but instead represents a compromise with suboptimal activity for most PTS permeases. The evolutionary implications are discussed.
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Affiliation(s)
- Yossef Lopez-de Los Santos
- Departamento de Ingeniería Celular y Biocatálisis del Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenue Universidad 2001, Cuernavaca, Morelos, México, P. C. 62210
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19
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Dell' Antone P. Energy metabolism in cancer cells: how to explain the Warburg and Crabtree effects? Med Hypotheses 2012; 79:388-92. [PMID: 22770870 DOI: 10.1016/j.mehy.2012.06.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 06/01/2012] [Accepted: 06/03/2012] [Indexed: 11/26/2022]
Abstract
Cancer cells have a greater need for energy and a ready supply of the building blocks necessary for the synthesis of macromolecules (nucleotides, protein, lipids) in order to duplicate genome and biomass. The hypothesis can be postulated that those precursors for synthetic processes, which can only be furnished by glycolysis, cannot be sufficiently recruited from external sources (the blood stream) and that glycolysis is necessarily markedly activated. It can also be hypothesized that the Krebs cycle, which also furnishes precursors for macromolecule synthesis to meet the requirements of proliferating cells, is depleted of intermediates. In view of its cyclic nature requiring not only pyruvate but also oxalacetate as the "last" metabolite of the reaction sequence for its sustenance, the Krebs cycle may be partially inactivated. While anaplerotic reactions and other sources (amino acids and fatty acids) could supply the cycle with intermediates, those pathways constitute futile cycles for amino and fatty acids as they would be partially degraded in the cycle and the intermediates thus obtained would be exported into the cytoplasm for synthetic processes with no advantage for the cell. It is also hypothesized that glutamine, an important fuel for cancer cells and playing a critical role in anaplerosis, may not contribute to reinforce the cycle; malate and α-ketoglutarate, two products of glutamine metabolism, might be exported from the mitochondria as precursors of biosynthetic pathways. It is possible then that malate, used for NADPH production required in the biosynthetic pathways, and glycerol-phosphate, too used for biosynthetic purposes (lipid biosynthesis), are unable to sustain the mitochondrial redox shuttles reducing the respiratory capacity of the mitochondria. Low shuttle capacity implies that NADH generated by glycolysis needs to be continuously re-oxidized in the cytoplasm via lactate dehydrogenase to maintain glycolysis fully activated, causing the abnormal lactate production observed in cancer. The paper goes onto discuss the essential role of glucose in cancer cell proliferation also in inducing the Crabtree effect. It is finally hypothesized that respiration inhibition after cancer cells have been supplied with glucose is due to reactivation in a suited medium of biosynthetic pathways with the consequences described above.
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Affiliation(s)
- Paolo Dell' Antone
- Dipartimento di Scienze Biomediche Sperimentali, Via Colombo 3, Padova, Italy.
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20
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Soares-Silva I, Sá-Pessoa J, Myrianthopoulos V, Mikros E, Casal M, Diallinas G. A substrate translocation trajectory in a cytoplasm-facing topological model of the monocarboxylate/H⁺ symporter Jen1p. Mol Microbiol 2011; 81:805-17. [PMID: 21651629 DOI: 10.1111/j.1365-2958.2011.07729.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Previous mutational analysis of Jen1p, a Saccharomyces cerevisiae monocarboxylate/H⁺ symporter of the Major Facilitator Superfamily, has suggested that the consensus sequence ³⁷⁹NXX[S/T]HX[S/T]QD³⁸⁷ in transmembrane segment VII (TMS-VII) is part of the substrate translocation pathway. Here, we rationally design, analyse and show that several novel mutations in TMS-V and TMS-XI directly modify Jen1p function. Among the residues studied, F270 (TMS-V) and Q498 (TMS-XI) are critical specificity determinants for the distinction of mono- from dicarboxylates, and N501 (TMS-XI) is a critical residue for function. Using a model created on the basis of Jen1p similarity with the GlpT permease, we show that all polar residues critical for function within TMS-VII and TMS-XI (N379, H383, D387, Q498, N501) are perfectly aligned in an imaginary axis that lies parallel to the protein pore. This model and subsequent mutational analysis further reveal that an additional polar residue facing the pore, R188 (TMS-II), is irreplaceable for function. Our model also justifies the role of F270 and Q498 in substrate specificity. Finally, docking calculations reveal a 'trajectory-like' substrate displacement within the Jen1p pore, where R188 plays a major dynamic role mediating the orderly relocation of the substrate by subsequent H-bond interactions involving itself and residues H383, N501 and Q498.
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Affiliation(s)
- Isabel Soares-Silva
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal
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21
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Slavic K, Krishna S, Derbyshire ET, Staines HM. Plasmodial sugar transporters as anti-malarial drug targets and comparisons with other protozoa. Malar J 2011; 10:165. [PMID: 21676209 PMCID: PMC3135577 DOI: 10.1186/1475-2875-10-165] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Accepted: 06/15/2011] [Indexed: 01/28/2023] Open
Abstract
Glucose is the primary source of energy and a key substrate for most cells. Inhibition of cellular glucose uptake (the first step in its utilization) has, therefore, received attention as a potential therapeutic strategy to treat various unrelated diseases including malaria and cancers. For malaria, blood forms of parasites rely almost entirely on glycolysis for energy production and, without energy stores, they are dependent on the constant uptake of glucose. Plasmodium falciparum is the most dangerous human malarial parasite and its hexose transporter has been identified as being the major glucose transporter. In this review, recent progress regarding the validation and development of the P. falciparum hexose transporter as a drug target is described, highlighting the importance of robust target validation through both chemical and genetic methods. Therapeutic targeting potential of hexose transporters of other protozoan pathogens is also reviewed and discussed.
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Affiliation(s)
- Ksenija Slavic
- Centre for Infection, Division of Cellular and Molecular Medicine, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK.
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22
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Nutrient transport and pathogenesis in selected parasitic protozoa. EUKARYOTIC CELL 2011; 10:483-93. [PMID: 21216940 DOI: 10.1128/ec.00287-10] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Parasitic protozoa, such as malaria parasites, trypanosomes, and Leishmania, acquire a plethora of nutrients from their hosts, employing transport proteins located in the plasma membrane of the parasite. Application of molecular genetic approaches and the completion of genome projects have allowed the identification and functional characterization of a cohort of transporters and their genes in these parasites. This review focuses on a subset of these permeases that have been studied in some detail, that import critical nutrients, and that provide examples of approaches being undertaken broadly with these and other parasite transporters. Permeases reviewed include those for hexoses, purines, iron, polyamines, carboxylates, and amino acids. Topics of special emphasis include structure-function approaches, critical roles for transporters in parasite viability and physiology, regulation of transporter expression, and subcellular targeting. Investigations of parasite transporters impact a broad spectrum of basic biological problems in these protozoa.
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23
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Feng X, Feistel T, Buffalo C, McCormack A, Kruvand E, Rodriguez-Contreras D, Akopyants NS, Umasankar PK, David L, Jardim A, Beverley SM, Landfear SM. Remodeling of protein and mRNA expression in Leishmania mexicana induced by deletion of glucose transporter genes. Mol Biochem Parasitol 2010; 175:39-48. [PMID: 20869991 DOI: 10.1016/j.molbiopara.2010.08.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 08/26/2010] [Accepted: 08/27/2010] [Indexed: 11/19/2022]
Abstract
Glucose is a major nutrient in the insect vector stage of Leishmania parasites. Glucose transporter null mutants of Leishmania mexicana exhibit profound phenotypic changes in both insect stage promastigotes and mammalian host stage amastigotes that reside within phagolysosomes of host macrophages. Some of these phenotypic changes could be either mediated or attenuated by changes in gene expression that accompany deletion of the glucose transporter genes. To search for changes in protein expression, the profile of proteins detected on two-dimensional gels was compared for wild type and glucose transporter null mutant promastigotes. A total of 50 spots whose intensities changed significantly and consistently in multiple experiments were detected, suggesting that a cohort of proteins is altered in expression levels in the null mutant parasites. Following identification of proteins by mass spectrometry, 3 such regulated proteins were chosen for more detailed analysis: mitochondrial aldehyde dehydrogenase, ribokinase, and hexokinase. Immunoblots employing antisera against these enzymes confirmed that their levels were upregulated, both in glucose transporter null mutants and in wild type parasites starved for glucose. Quantitative reverse transcriptase PCR (qRT-PCR) revealed that the levels of mRNAs encoding these enzymes were also enhanced. Global expression profiling using microarrays revealed a limited number of additional changes, although the sensitivity of the microarrays to detect modest changes in amplitude was less than that of two-dimensional gels. Hence, there is likely to be a network of proteins whose expression levels are altered by genetic ablation of glucose transporters, and much of this regulation may be reflected by changes in the levels of the cognate mRNAs. Some of these changes in protein expression may reflect an adaptive response of the parasites to limitation of glucose.
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Affiliation(s)
- Xiuhong Feng
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239, USA
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