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Rosado-Quiñones AM, Colón-Lorenzo EE, Pala ZR, Bosch J, Kudyba K, Kudyba H, Leed SE, Roncal N, Baerga-Ortiz A, Roche-Lima A, Gerena Y, Fidock DA, Roth A, Vega-Rodríguez J, Serrano AE. Novel hydrazone compounds with broad-spectrum antiplasmodial activity and synergistic interactions with antimalarial drugs. Antimicrob Agents Chemother 2024:e0164323. [PMID: 38639491 DOI: 10.1128/aac.01643-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/20/2024] [Indexed: 04/20/2024] Open
Abstract
The development of novel antiplasmodial compounds with broad-spectrum activity against different stages of Plasmodium parasites is crucial to prevent malaria disease and parasite transmission. This study evaluated the antiplasmodial activity of seven novel hydrazone compounds (referred to as CB compounds: CB-27, CB-41, CB-50, CB-53, CB-58, CB-59, and CB-61) against multiple stages of Plasmodium parasites. All CB compounds inhibited blood stage proliferation of drug-resistant or sensitive strains of Plasmodium falciparum in the low micromolar to nanomolar range. Interestingly, CB-41 exhibited prophylactic activity against hypnozoites and liver schizonts in Plasmodium cynomolgi, a primate model for Plasmodium vivax. Four CB compounds (CB-27, CB-41, CB-53, and CB-61) inhibited P. falciparum oocyst formation in mosquitoes, and five CB compounds (CB-27, CB-41, CB-53, CB-58, and CB-61) hindered the in vitro development of Plasmodium berghei ookinetes. The CB compounds did not inhibit the activation of P. berghei female and male gametocytes in vitro. Isobologram assays demonstrated synergistic interactions between CB-61 and the FDA-approved antimalarial drugs, clindamycin and halofantrine. Testing of six CB compounds showed no inhibition of Plasmodium glutathione S-transferase as a putative target and no cytotoxicity in HepG2 liver cells. CB compounds are promising candidates for further development as antimalarial drugs against multidrug-resistant parasites, which could also prevent malaria transmission.
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Affiliation(s)
- Angélica M Rosado-Quiñones
- Department of Microbiology and Medical Zoology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Emilee E Colón-Lorenzo
- Department of Microbiology and Medical Zoology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Zarna Rajeshkumar Pala
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Jürgen Bosch
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, USA
- InterRayBio, LLC, Cleveland, Ohio, USA
| | - Karl Kudyba
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Heather Kudyba
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Susan E Leed
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Norma Roncal
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Abel Baerga-Ortiz
- Department of Biochemistry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - Abiel Roche-Lima
- RCMI Program, Medical Science Campus, University of Puerto Rico, San Juan, Puerto Rico
| | - Yamil Gerena
- Department of Pharmacology and Toxicology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
| | - David A Fidock
- Department of Microbiology and Immunology, Columbia University, New York, New York, USA
- Division of Infectious Diseases, Department of Medicine, Center for Malaria Therapeutics and Antimicrobial Resistance, Columbia University Medical Center, New York, New York, USA
| | - Alison Roth
- Department of Drug Discovery, Experimental Therapeutics Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Joel Vega-Rodríguez
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Adelfa E Serrano
- Department of Microbiology and Medical Zoology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico
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2
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Colón-Lorenzo EE, Colón-López DD, Vega-Rodríguez J, Dupin A, Fidock DA, Baerga-Ortiz A, Ortiz JG, Bosch J, Serrano AE. Structure-Based Screening of Plasmodium berghei Glutathione S-Transferase Identifies CB-27 as a Novel Antiplasmodial Compound. Front Pharmacol 2020; 11:246. [PMID: 32256353 PMCID: PMC7090221 DOI: 10.3389/fphar.2020.00246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 02/24/2020] [Indexed: 11/13/2022] Open
Abstract
Plasmodium falciparum parasites are increasingly drug-resistant, requiring the search for novel antimalarials with distinct modes of action. Enzymes in the glutathione pathway, including glutathione S-transferase (GST), show promise as novel antimalarial targets. This study aims to better understand the biological function of Plasmodium GST, assess its potential as a drug target, and identify novel antiplasmodial compounds using the rodent model P. berghei. By using reverse genetics, we provided evidence that GST is essential for survival of P. berghei intra-erythrocytic stages and is a valid target for drug development. A structural model of the P. berghei glutathione S-transferase (PbGST) protein was generated and used in a structure-based screening of 900,000 compounds from the ChemBridge Hit2Lead library. Forty compounds were identified as potential inhibitors and analyzed in parasite in vitro drug susceptibility assays. One compound, CB-27, exhibited antiplasmodial activity with an EC50 of 0.5 μM toward P. berghei and 0.9 μM toward P. falciparum multidrug-resistant Dd2 clone B2 parasites. Moreover, CB-27 showed a concentration-dependent inhibition of the PbGST enzyme without inhibiting the human ortholog. A shape similarity screening using CB-27 as query resulted in the identification of 24 novel chemical scaffolds, with six of them showing antiplasmodial activity ranging from EC50 of 0.6-4.9 μM. Pharmacokinetic and toxicity predictions suggest that the lead compounds have drug-likeness properties. The antiplasmodial potency, the absence of hemolytic activity, and the predicted drug-likeness properties position these compounds for lead optimization and further development as antimalarials.
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Affiliation(s)
- Emilee E. Colón-Lorenzo
- Department of Microbiology and Medical Zoology, University of Puerto Rico School of Medicine, San Juan, PR, United States
| | - Daisy D. Colón-López
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Joel Vega-Rodríguez
- Department of Microbiology and Medical Zoology, University of Puerto Rico School of Medicine, San Juan, PR, United States
| | - Alice Dupin
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, United States
| | - David A. Fidock
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, United States
- Division of Infectious Diseases, Department of Medicine, Columbia University Medical Center, New York, NY, United States
| | - Abel Baerga-Ortiz
- Department of Biochemistry, University of Puerto Rico School of Medicine, San Juan, PR, United States
| | - José G. Ortiz
- Department of Pharmacology and Toxicology, University of Puerto Rico School of Medicine, San Juan, PR, United States
| | - Jürgen Bosch
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
- Division of Pediatric Pulmonology and Allergy/Immunology, Case Western Reserve University, Cleveland, OH, United States
- InterRayBio, LLC, Baltimore, MD, United States
| | - Adelfa E. Serrano
- Department of Microbiology and Medical Zoology, University of Puerto Rico School of Medicine, San Juan, PR, United States
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3
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Perner J, Kotál J, Hatalová T, Urbanová V, Bartošová-Sojková P, Brophy PM, Kopáček P. Inducible glutathione S-transferase (IrGST1) from the tick Ixodes ricinus is a haem-binding protein. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018. [PMID: 29526768 DOI: 10.1016/j.ibmb.2018.02.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Blood-feeding parasites are inadvertently exposed to high doses of potentially cytotoxic haem liberated upon host blood digestion. Detoxification of free haem is a special challenge for ticks, which digest haemoglobin intracellularly. Ticks lack a haem catabolic mechanism, mediated by haem oxygenase, and need to dispose of vast majority of acquired haem via its accumulation in haemosomes. The knowledge of individual molecules involved in the maintenance of haem homeostasis in ticks is still rather limited. RNA-seq analyses of the Ixodes ricinus midguts from blood- and serum-fed females identified an abundant transcript of glutathione S-transferase (gst) to be substantially up-regulated in the presence of red blood cells in the diet. Here, we have determined the full sequence of this encoding gene, ir-gst1, and found that it is homologous to the delta-/epsilon-class of GSTs. Phylogenetic analyses across related chelicerates revealed that only one clear IrGST1 orthologue could be found in each available transcriptome from hard and soft ticks. These orthologues create a well-supported clade clearly separated from other ticks' or mites' delta-/epsilon-class GSTs and most likely evolved as an adaptation to tick blood-feeding life style. We have confirmed that IrGST1 expression is induced by dietary haem(oglobin), and not by iron or other components of host blood. Kinetic properties of recombinant IrGST1 were evaluated by model and natural GST substrates. The enzyme was also shown to bind haemin in vitro as evidenced by inhibition assay, VIS spectrophotometry, gel filtration, and affinity chromatography. In the native state, IrGST1 forms a dimer which further polymerises upon binding of excessive amount of haemin molecules. Due to susceptibility of ticks to haem as a signalling molecule, we speculate that the expression of IrGST1 in tick midgut functions as intracellular buffer of labile haem pool to ameliorate its cytotoxic effects upon haemoglobin intracellular hydrolysis.
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Affiliation(s)
- Jan Perner
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budějovice, Czech Republic.
| | - Jan Kotál
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Tereza Hatalová
- Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Veronika Urbanová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Pavla Bartošová-Sojková
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Peter M Brophy
- Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, SY23 3DA, UK
| | - Petr Kopáček
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic
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4
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Bocedi A, Fabrini R, Lo Bello M, Caccuri AM, Federici G, Mannervik B, Cornish-Bowden A, Ricci G. Evolution of Negative Cooperativity in Glutathione Transferase Enabled Preservation of Enzyme Function. J Biol Chem 2016; 291:26739-26749. [PMID: 27815499 DOI: 10.1074/jbc.m116.749507] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 11/03/2016] [Indexed: 11/06/2022] Open
Abstract
Negative cooperativity in enzyme reactions, in which the first event makes subsequent events less favorable, is sometimes well understood at the molecular level, but its physiological role has often been obscure. Negative cooperativity occurs in human glutathione transferase (GST) GSTP1-1 when it binds and neutralizes a toxic nitric oxide adduct, the dinitrosyl-diglutathionyl iron complex (DNDGIC). However, the generality of this behavior across the divergent GST family and its evolutionary significance were unclear. To investigate, we studied 16 different GSTs, revealing that negative cooperativity is present only in more recently evolved GSTs, indicating evolutionary drift in this direction. In some variants, Hill coefficients were close to 0.5, the highest degree of negative cooperativity commonly observed (although smaller values of nH are theoretically possible). As DNDGIC is also a strong inhibitor of GSTs, we suggest negative cooperativity might have evolved to maintain a residual conjugating activity of GST against toxins even in the presence of high DNDGIC concentrations. Interestingly, two human isoenzymes that play a special protective role, safeguarding DNA from DNDGIC, display a classical half-of-the-sites interaction. Analysis of GST structures identified elements that could play a role in negative cooperativity in GSTs. Beside the well known lock-and-key and clasp motifs, other alternative structural interactions between subunits may be proposed for a few GSTs. Taken together, our findings suggest the evolution of self-preservation of enzyme function as a novel facility emerging from negative cooperativity.
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Affiliation(s)
- Alessio Bocedi
- From the Department of Chemical Sciences and Technologies
| | | | | | - Anna Maria Caccuri
- Department of Experimental Medicine and Surgery, University of Rome, Tor Vergata, Rome 00133, Italy
| | | | - Bengt Mannervik
- Department of Neurochemistry, Stockholm University SE-10691 Stockholm, Sweden, and
| | - Athel Cornish-Bowden
- Aix Marseille Université, CNRS, Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, 13009 Marseille, France
| | - Giorgio Ricci
- From the Department of Chemical Sciences and Technologies,
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5
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Al-Qattan MN, Mordi MN, Mansor SM. Assembly of ligands interaction models for glutathione-S-transferases from Plasmodium falciparum, human and mouse using enzyme kinetics and molecular docking. Comput Biol Chem 2016; 64:237-249. [PMID: 27475235 DOI: 10.1016/j.compbiolchem.2016.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/08/2016] [Accepted: 07/16/2016] [Indexed: 01/12/2023]
Abstract
BACKGROUND Glutathione-s-transferases (GSTs) are enzymes that principally catalyze the conjugation of electrophilic compounds to the endogenous nucleophilic glutathione substrate, besides, they have other non-catalytic functions. The Plasmodium falciparum genome encodes a single isoform of GST (PfGST) which is involved in buffering the toxic heme, thus considered a potential anti-malarial target. In mammals several classes of GSTs are available, each of various isoforms. The human (human GST Pi-1 or hGSTP1) and mouse (murine GST Mu-1 or mGSTM1) GST isoforms control cellular apoptosis by interaction with signaling proteins, thus considered as potential anti-cancer targets. In the course of GSTs inhibitors development, the models of ligands interactions with GSTs are used to guide rational molecular modification. In the absence of X-ray crystallographic data, enzyme kinetics and molecular docking experiments can aid in addressing ligands binding modes to the enzymes. METHODS Kinetic studies were used to investigate the interactions between the three GSTs and each of glutathione, 1-chloro-2,4-dinitrobenzene, cibacron blue, ethacrynic acid, S-hexyl glutathione, hemin and protoporphyrin IX. Since hemin displacement is intended for PfGST inhibitors, the interactions between hemin and other ligands at PfGST binding sites were studied kinetically. Computationally determined binding modes and energies were interlinked with the kinetic results to resolve enzymes-ligands interaction models at atomic level. RESULTS The results showed that hemin and cibacron blue have different binding modes in the three GSTs. Hemin has two binding sites (A and B) with two binding modes at site-A depending on presence of GSH. None of the ligands were able to compete hemin binding to PfGST except ethacrynic acid. Besides bind differently in GSTs, the isolated anthraquinone moiety of cibacron blue is not maintaining sufficient interactions with GSTs to be used as a lead. Similarly, the ethacrynic acid uses water bridges to mediate interactions with GSTs and at least the conjugated form of EA is the true hemin inhibitor, thus EA may not be a suitable lead. CONCLUSIONS Glutathione analogues with bulky substitution at thiol of cysteine moiety or at γ-amino group of γ-glutamine moiety may be the most suitable to provide GST inhibitors with hemin competition.
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Affiliation(s)
| | - Mohd Nizam Mordi
- Centre For Drug Research, Universiti Sains Malaysia. Gelugor 11700 Penang, Malaysia
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6
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Perbandt M, Eberle R, Fischer-Riepe L, Cang H, Liebau E, Betzel C. High resolution structures of Plasmodium falciparum GST complexes provide novel insights into the dimer-tetramer transition and a novel ligand-binding site. J Struct Biol 2015; 191:365-75. [PMID: 26072058 DOI: 10.1016/j.jsb.2015.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 10/23/2022]
Abstract
Protection from oxidative stress and efficient redox regulation are essential for malarial parasites which have to grow and multiply rapidly in pro-oxidant rich environments. Therefore, redox active proteins currently belong to the most attractive antimalarial drug targets. The glutathione S-transferase from Plasmodium falciparum (PfGST) is a redox active protein displaying a peculiar dimer-tetramer transition that causes full enzyme-inactivation. This distinct structural feature is absent in mammalian GST isoenzyme counterparts. A flexible loop between residues 113-119 has been reported to be necessary for this tetramerization process. However, here we present structural data of a modified PfGST lacking loop 113-119 at 1.9 Å resolution. Our results clearly show that this loop is not essential for the formation of stable tetramers. Moreover we present for the first time the structures of both, the inactive and tetrameric state at 1.7 Å and the active dimeric state in complex with reduced glutathione at 2.4 Å resolution. Surprisingly, the structure of the inactive tetrameric state reveals a novel non-substrate binding-site occupied by a 2-(N-morpholino) ethane sulfonic acid (MES) molecule in each monomer. Although it is known that the PfGST has the ability to bind lipophilic anionic ligands, the location of the PfGST ligand-binding site remained unclear up to now.
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Affiliation(s)
- Markus Perbandt
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory of Structural Biology of Infection and Inflammation, c/o DESY, Notkestr. 85, Build. 22a, D-22603 Hamburg, Germany; Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf (UKE), D-20246 Hamburg, Germany; The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany.
| | - Raphael Eberle
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory of Structural Biology of Infection and Inflammation, c/o DESY, Notkestr. 85, Build. 22a, D-22603 Hamburg, Germany
| | - Lena Fischer-Riepe
- Department of Molecular Physiology, University of Münster, Schlossplatz 8, D-48143 Münster, Germany
| | - Huaixing Cang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Eva Liebau
- Department of Molecular Physiology, University of Münster, Schlossplatz 8, D-48143 Münster, Germany
| | - Christian Betzel
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory of Structural Biology of Infection and Inflammation, c/o DESY, Notkestr. 85, Build. 22a, D-22603 Hamburg, Germany; The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany
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7
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Asn112 in Plasmodium falciparum glutathione S-transferase is essential for induced reversible tetramerization by phosphate or pyrophosphate. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1427-36. [DOI: 10.1016/j.bbapap.2014.04.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 04/04/2014] [Accepted: 04/22/2014] [Indexed: 11/22/2022]
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8
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Quesada-Soriano I, Barón C, García-Maroto F, Aguilera AM, García-Fuentes L. Calorimetric Studies of Ligands Binding to Glutathione S-Transferase from the Malarial Parasite Plasmodium falciparum. Biochemistry 2013; 52:1980-9. [DOI: 10.1021/bi400007g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Indalecio Quesada-Soriano
- Department
of Chemistry and Physics, University of Almerı́a, Agrifood Campus of International
Excellence (ceiA3), Ctra de Sacramento s/n, 04120 Almerı́a,
Spain
| | - Carmen Barón
- Department
of Chemistry and Physics, University of Almerı́a, Agrifood Campus of International
Excellence (ceiA3), Ctra de Sacramento s/n, 04120 Almerı́a,
Spain
| | - Federico García-Maroto
- Department
of Chemistry and Physics, University of Almerı́a, Agrifood Campus of International
Excellence (ceiA3), Ctra de Sacramento s/n, 04120 Almerı́a,
Spain
| | - Ana M. Aguilera
- Department
of Chemistry and Physics, University of Almerı́a, Agrifood Campus of International
Excellence (ceiA3), Ctra de Sacramento s/n, 04120 Almerı́a,
Spain
| | - Luís García-Fuentes
- Department
of Chemistry and Physics, University of Almerı́a, Agrifood Campus of International
Excellence (ceiA3), Ctra de Sacramento s/n, 04120 Almerı́a,
Spain
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9
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Abstract
SIGNIFICANCE Parasitic infections continue to be a major problem for global human health. Vaccines are practically not available and chemotherapy is highly unsatisfactory. One approach toward a novel antiparasitic drug development is to unravel pathways that may be suited as future targets. Parasitic organisms show a remarkable diversity with respect to the nature and functions of their main low-molecular-mass antioxidants and many of them developed pathways that do not have a counterpart in their mammalian hosts. RECENT ADVANCES Work of the last years disclosed the individual antioxidants employed by parasites and their distinct pathways. Entamoeba, Trichomonas, and Giardia directly use cysteine as main low-molecular-mass thiol but have divergent cysteine metabolisms. Malarial parasites rely exclusively on cysteine uptake and generate glutathione (GSH) as main free thiol as do metazoan parasites. Trypanosomes and Leishmania have a unique trypanothione-based thiol metabolism but employ individual mechanisms for their cysteine supply. In addition, some trypanosomatids synthesize ovothiol A and/or ascorbate. Various essential parasite enzymes such as trypanothione synthetase and trypanothione reductase in Trypanosomatids and the Schistosoma thioredoxin GSH reductase are currently intensively explored as drug target molecules. CRITICAL ISSUES Essentiality is a prerequisite but not a sufficient property of an enzyme to become a suited drug target. The availability of an appropriate in vivo screening system and many other factors are equally important. FUTURE DIRECTIONS The current organism-wide RNA-interference and proteome analyses are supposed to reveal many more interesting candidates for future drug development approaches directed against the parasite antioxidant defense systems.
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10
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Chronopoulou E, Madesis P, Asimakopoulou B, Platis D, Tsaftaris A, Labrou NE. Catalytic and structural diversity of the fluazifop-inducible glutathione transferases from Phaseolus vulgaris. PLANTA 2012; 235:1253-1269. [PMID: 22203322 DOI: 10.1007/s00425-011-1572-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 12/05/2011] [Indexed: 05/31/2023]
Abstract
Plant glutathione transferases (GSTs) comprise a large family of inducible enzymes that play important roles in stress tolerance and herbicide detoxification. Treatment of Phaseolus vulgaris leaves with the aryloxyphenoxypropionic herbicide fluazifop-p-butyl resulted in induction of GST activities. Three inducible GST isoenzymes were identified and separated by affinity chromatography. Their full-length cDNAs with complete open reading frame were isolated using RACE-RT and information from N-terminal amino acid sequences. Analysis of the cDNA clones showed that the deduced amino acid sequences share high homology with GSTs that belong to phi and tau classes. The three isoenzymes were expressed in E. coli and their substrate specificity was determined towards 20 different substrates. The results showed that the fluazifop-inducible glutathione transferases from P. vulgaris (PvGSTs) catalyze a broad range of reactions and exhibit quite varied substrate specificity. Molecular modeling and structural analysis was used to identify key structural characteristics and to provide insights into the substrate specificity and the catalytic mechanism of these enzymes. These results provide new insights into catalytic and structural diversity of GSTs and the detoxifying mechanism used by P. vulgaris.
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Affiliation(s)
- Evangelia Chronopoulou
- Laboratory of Enzyme Technology, Department of Agricultural Biotechnology, Agricultural University of Athens, 75 Iera Odos Street, 11855 Athens, Greece
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11
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Dang DT, Schill J, Brunsveld L. Cucurbit[8]uril-mediated protein homotetramerization. Chem Sci 2012. [DOI: 10.1039/c2sc20625k] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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12
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Fabrini R, De Luca A, Stella L, Mei G, Orioni B, Ciccone S, Federici G, Lo Bello M, Ricci G. Monomer-dimer equilibrium in glutathione transferases: a critical re-examination. Biochemistry 2009; 48:10473-82. [PMID: 19795889 DOI: 10.1021/bi901238t] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glutathione transferases (GSTs) are dimeric enzymes involved in cell detoxification versus many endogenous toxic compounds and xenobiotics. In addition, single monomers of GSTs appear to be involved in particular protein-protein interactions as in the case of the pi class GST that regulates the apoptotic process by means of a GST-c-Jun N-terminal kinase complex. Thus, the dimer-monomer transition of GSTs may have important physiological relevance, but many studies reached contrasting conclusions both about the modality and extension of this event and about the catalytic competence of a single subunit. This paper re-examines the monomer-dimer question in light of novel experiments and old observations. Recent papers claimed the existence of a predominant monomeric and active species among pi, alpha, and mu class GSTs at 20-40 nM dilution levels, reporting dissociation constants (K(d)) for dimeric GST of 5.1, 0.34, and 0.16 microM, respectively. However, we demonstrate here that only traces of monomers could be found at these concentrations since all these enzymes display K(d) values of <<1 nM, values thousands of times lower than those reported previously. Time-resolved and steady-state fluorescence anisotropy experiments, two-photon fluorescence correlation spectroscopy, kinetic studies, and docking simulations have been used to reach such conclusions. Our results also indicate that there is no clear evidence of the existence of a fully active monomer. Conversely, many data strongly support the idea that the monomeric form is scarcely active or fully inactive.
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Affiliation(s)
- Raffaele Fabrini
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, 00133 Rome, Italy
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