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Repurposing Strategy of Atorvastatin against Trypanosoma cruzi: In Vitro Monotherapy and Combined Therapy with Benznidazole Exhibit Synergistic Trypanocidal Activity. Antimicrob Agents Chemother 2018; 62:AAC.00979-18. [PMID: 29987140 DOI: 10.1128/aac.00979-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 06/22/2018] [Indexed: 01/22/2023] Open
Abstract
Statins are inhibitors of cholesterol synthesis, but other biological properties, such as antimicrobial effects, have also been assigned to them, leading to their designation as pleiotropic agents. Our goal was to investigate the activity and selectivity of atorvastatin (AVA) against Trypanosoma cruzi by using in vitro models, aiming for more effective and safer therapeutic options through drug repurposing proposals for monotherapy and therapy in combination with benznidazole (BZ). Phenotypic screening was performed with different strains (Tulahuen [discrete typing unit {DTU} VI] and Y [DTU II]) and forms (intracellular forms, bloodstream trypomastigotes, and tissue-derived trypomastigotes) of the parasite. On assay of the Tulahuen strain, AVA was more active against intracellular amastigotes (selectivity index [SI] = 3). Also, against a parasite of another DTU (Y strain), this statin was more active (2.1-fold) and selective (2.4-fold) against bloodstream trypomastigotes (SI = 51) than against the intracellular forms (SI = 20). A cytomorphological approach using phalloidin-rhodamine permitted us to verify that AVA did not induced cell density reduction and that cardiac cells (CC) maintained their typical cytoarchitecture. Combinatory approaches using fixed-ratio methods showed that AVA and BZ gave synergistic interactions against both trypomastigotes and intracellular forms (mean sums of fractional inhibitory concentration indexes [∑FICIs] of 0.46 ± 0.12 and 0.48 ± 0.03, respectively). Thus, the repurposing strategy for AVA, especially in combination with BZ, which leads to a synergistic effect, is encouraging for future studies to identify novel therapeutic protocols for Chagas disease treatment.
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Bioconversion of methanol to value-added mevalonate by engineered Methylobacterium extorquens AM1 containing an optimized mevalonate pathway. Appl Microbiol Biotechnol 2015; 100:2171-82. [DOI: 10.1007/s00253-015-7078-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 09/20/2015] [Accepted: 10/12/2015] [Indexed: 12/21/2022]
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Dinesh N, Pallerla DSR, Kaur PK, Kishore Babu N, Singh S. Exploring Leishmania donovani 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) as a potential drug target by biochemical, biophysical and inhibition studies. Microb Pathog 2013; 66:14-23. [PMID: 24239940 DOI: 10.1016/j.micpath.2013.11.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 10/29/2013] [Accepted: 11/01/2013] [Indexed: 01/24/2023]
Abstract
3-Hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase (HMGR), an NADPH dependant enzyme catalyzes the synthesis of mevalonic acid from HMG-CoA required for isoprenoid biosynthesis. The HMGR gene from Leishmania donovani was cloned and expressed. Genome analysis of L. donovani revealed that HMGR gene having an open reading frame of 1305 bp encodes a putative protein of 434 amino acids. LdHMGR showed optimal activity at pH 7.2 and temperature 37 °C. Kinetic analysis of this enzyme revealed Km values of 35.7 ± 2.5 μM for (R,S)-HMG-CoA and 70 ± 7.9 μM for the cofactor NADPH. On tryptophan fluorescence quenching, the Stern Volmer constant (Ksv), binding constant (Ka) and protein:cofactor stoichiometry for interaction of NADPH cofactor with the enzyme were found to be 6.0 ± 0.7 M(-1), 0.17 μM and 0.72 respectively. Polyclonal anti-rat HMGR antibody detected a band of ∼45 kDa in all phases of promastigote growth. Biophysical analysis of the secondary structure of LdHMGR confirmed the presence of 25.7 ± 0.35% alpha helicity. Thermal denaturation studies showed extreme stability of the enzyme with 60% helical structure retained at 90 °C. Statins (simvastatin and atorvastatin) and non-statin (resveratrol) effectively inhibited the growth of L. donovani promastigotes as well as the catalytic activity of the recombinant LdHMGR. Atorvastatin was found to be most potent antileishmanial inhibitor with an IC50 value of 19.4 ± 3.07 μM and a very lower concentration of 315.5 ± 2.1 nM was enough to cause 50% recombinant LdHMGR enzyme inhibition suggesting direct interaction with the rate limiting enzyme of the ergosterol biosynthetic pathway. Exogenous supplementation of ergosterol in case of atorvastatin and resveratrol treated cells caused complete reversal of growth inhibition whereas simvastatin was found to be ergosterol refractory. Cholesterol supplementation however, failed to overcome growth inhibition in all the cases. Overall our study emphasizes on exploring LdHMGR as a potential drug target for the development of novel antileishmanial agents.
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Affiliation(s)
- Neeradi Dinesh
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali 160062, Punjab, India
| | - Dheeraj Sree Ram Pallerla
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali 160062, Punjab, India
| | - Preet Kamal Kaur
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali 160062, Punjab, India
| | - Neerupudi Kishore Babu
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali 160062, Punjab, India
| | - Sushma Singh
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali 160062, Punjab, India.
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Alves-Ferreira M, Guimarães ACR, Capriles PVDSZ, Dardenne LE, Degrave WM. A new approach for potential drug target discovery through in silico metabolic pathway analysis using Trypanosoma cruzi genome information. Mem Inst Oswaldo Cruz 2009; 104:1100-10. [DOI: 10.1590/s0074-02762009000800006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 10/28/2009] [Indexed: 11/22/2022] Open
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5
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Panda T, Devi VA. Regulation and degradation of HMGCo-A reductase. Appl Microbiol Biotechnol 2004; 66:143-52. [PMID: 15558272 DOI: 10.1007/s00253-004-1720-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2004] [Revised: 07/15/2004] [Accepted: 07/16/2004] [Indexed: 11/26/2022]
Abstract
The enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) controls the biosynthesis of cholesterol. Hypercholesterolemia and atherosclerosis are critical health risk factors. One way of controlling these risk factors is to manipulate regulation as well as degradation of HMGR. At present, a class of compounds called statins, which are HMGR inhibitors, are used for the treatment of hypercholesterolemia. However, statins suffer major setbacks as their use produces more adverse reactions than the desirable one of inhibiting the enzyme. Genetically engineered forms of HMGR are also studied in primitive life forms like bacteria, but detailed investigation of this enzyme in human systems is certainly required. Extensive studies have been made on the regulatory aspects of this enzyme, but no breakthrough is conspicuous in the clinical background to find an alternative treatment for hypercholesterolemia. The immediate need is to find an alternate way of regulating degradation of the enzyme. This review presents the importance of regulation and degradation of the HMGR enzyme in different systems to gain possible insight into alternative schemes for regulating this enzyme and, if these exist, the feasibility of extending them same to studies in mammalian systems. A high degree of similarity exists between mammalian and yeast HMGR. Detailed studies reported on the regulation and degradation of the yeast enzyme also throw more light on the mammalian system, leading to a better understanding of ways of controlling hypercholesterolemia.
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Affiliation(s)
- T Panda
- Department of Chemical Engineering, Indian Institute of Technology, Madras, Chennai, 600 036, India.
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6
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Peña-Diaz J, Montalvetti A, Flores CL, Constán A, Hurtado-Guerrero R, De Souza W, Gancedo C, Ruiz-Perez LM, Gonzalez-Pacanowska D. Mitochondrial localization of the mevalonate pathway enzyme 3-Hydroxy-3-methyl-glutaryl-CoA reductase in the Trypanosomatidae. Mol Biol Cell 2003; 15:1356-63. [PMID: 14699057 PMCID: PMC363142 DOI: 10.1091/mbc.e03-10-0720] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
3-Hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) is a key enzyme in the sterol biosynthesis pathway, but its subcellular distribution in the Trypanosomatidae family is somewhat controversial. Trypanosoma cruzi and Leishmania HMGRs are closely related in their catalytic domains to bacterial and eukaryotic enzymes described but lack an amino-terminal domain responsible for the attachment to the endoplasmic reticulum. In the present study, digitonin-titration experiments together with immunoelectron microscopy were used to establish the intracellular localization of HMGR in these pathogens. Results obtained with wild-type cells and transfectants overexpressing the enzyme established that HMGR in both T. cruzi and Leishmania major is localized primarily in the mitochondrion and that elimination of the mitochondrial targeting sequence in Leishmania leads to protein accumulation in the cytosolic compartment. Furthermore, T. cruzi HMGR is efficiently targeted to the mitochondrion in yeast cells. Thus, when the gene encoding T. cruzi HMGR was expressed in a hmg1 hmg2 mutant of Saccharomyces cerevisiae, the mevalonate auxotrophy of mutant cells was relieved, and immunoelectron analysis showed that the parasite enzyme exhibits a mitochondrial localization, suggesting a conservation between the targeting signals of both organisms.
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Affiliation(s)
- Javier Peña-Diaz
- Instituto de Parasitología y Biomedicina "López-Neyra", Consejo Superior de Investigaciones Científicas, 18001 Granada, Spain
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7
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Li S, Wagner CA, Friesen JA, Borst DW. 3-hydroxy-3-methylglutaryl-coenzyme A reductase in the lobster mandibular organ: regulation by the eyestalk. Gen Comp Endocrinol 2003; 134:147-55. [PMID: 14511985 DOI: 10.1016/s0016-6480(03)00246-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The mandibular organ (MO) of the lobster, Homarus americanus, produces the isoprenoid methyl farnesoate (MF), a compound related to insect juvenile hormone (JH). To better understand the synthesis and regulation of MF, we studied 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (HMGR), the rate-limiting enzyme in isoprenoid biosynthesis. Lobster HMGR had a Km of 11.4 microM for HMG-CoA, a Km of 14.8 microM for NADPH, and was at least 2000-fold more selective for this cofactor than for NADH. Lovastatin and mevalonic acid inhibited HMGR, with KI values of 1.3 nM and 25.3 microM, respectively, whereas MF, farnesoic acid, cholesterol, 20-hydroxyecdysone, and progesterone had no effect. Approximately 75% of the HMGR activity in lobster MO was soluble. Similar levels of HMGR activity were observed in all regions of the MO. Eyestalk removal increased MF synthesis and the activity of farnesoic acid O-methyltransferase (FAOMeT, the final step in MF synthesis) in the MO by 10.7- and 5.7-fold, respectively, and caused a 3.1-fold increase of HMGR activity. Injection of the eyestalk ablated lobsters with an extract of two sinus glands (SG), a neuroendocrine organ in the eyestalk, decreased MF synthesis, FAOMeT activity and HMGR activity to 3, 8, and 20%, respectively, of the levels observed in saline-treated animals. The regulation of crustacean HMGR by the SG suggests that the lobster MO is a useful model system for investigating the cellular regulation of HMGR activity.
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Affiliation(s)
- Sheng Li
- Department of Biological Science, Illinois State University, Normal, IL 61790, USA
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Hurtado-Guerrrero R, Peña-Díaz J, Montalvetti A, Ruiz-Pérez LM, González-Pacanowska D. Kinetic properties and inhibition of Trypanosoma cruzi 3-hydroxy-3-methylglutaryl CoA reductase. FEBS Lett 2002; 510:141-4. [PMID: 11801242 DOI: 10.1016/s0014-5793(01)03238-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A detailed kinetic analysis of the recombinant soluble enzyme 3-hydroxy-3-methylglutaryl CoA reductase (HMGR) from Trypanosoma cruzi has been performed. The enzyme catalyzes the normal anabolic reaction and the reductant is NADPH. It also catalyzes the oxidation of mevalonate but at a lower proportion compared to the anabolic reaction. We report that the catalytically active species of HMGR in solution is the tetrameric form. Fluvastatin inhibited competitively the enzyme while cerivastatin binds by a mechanism which is more accurately described by a biphasic process characteristic of a class of 'slow, tight-binding' inhibitors.
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Affiliation(s)
- Ramón Hurtado-Guerrrero
- Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas, C/Ventanilla 11, 18001 Granada, Spain
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9
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Ginger ML, Chance ML, Sadler IH, Goad LJ. The biosynthetic incorporation of the intact leucine skeleton into sterol by the trypanosomatid Leishmania mexicana. J Biol Chem 2001; 276:11674-82. [PMID: 11148203 DOI: 10.1074/jbc.m006850200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The amino acid leucine is efficiently used by the trypanosomatid Leishmania mexicana for sterol biosynthesis. The incubation of [2-(13)C]leucine with L. mexicana promastigotes in the presence of ketoconazole gave 14alpha-methylergosta-8,24(24(1))-3beta-ol as the major sterol, which was shown by mass spectrometry to contain up to six atoms of (13)C per molecule. (13)C NMR analysis of the 14alpha-methylergosta-8,24(24(1))-3beta-ol revealed that it was labeled in only six positions: C-2, C-6, C-11, C-12, C-16, and C-23. This established that the leucine skeleton is incorporated intact into the isoprenoid pathway leading to sterol; it is not converted first to acetyl-CoA, as in animals and plants, with utilization of the acetyl-CoA to regenerate 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA). An inhibitor of HMG-CoA synthase (L-659,699) blocked the incorporation of [1-(14)C]acetate into sterol but had no inhibitory effect on [U-(14)C]leucine incorporation. The HMG-CoA reductase inhibitor lovastatin inhibited promastigote growth and [U-(14)C]leucine incorporation into sterol. The addition of unlabeled mevalonic acid (MVA) overcame the lovastatin inhibition of growth and also diluted the incorporation of [1-(14)C]leucine into sterol. These results are compatible with two routes by which the leucine skeleton may enter intact into the isoprenoid pathway. The catabolism of leucine could generate HMG-CoA that is then directly reduced to MVA for incorporation into sterol. Alternatively, a compound produced as an intermediate in leucine breakdown to HMG-CoA (e.g. dimethylcrotonyl-CoA) could be directly reduced to produce an isoprene alcohol followed by phosphorylation to enter the isoprenoid pathway post-MVA.
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Affiliation(s)
- M L Ginger
- School of Biological Sciences, University of Liverpool, Life Sciences Building, Crown St., Liverpool L69 7ZB, United Kingdom
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10
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Fárez-Vidal ME, Gallego C, Ruiz-Pérez LM, González-Pacanowska D. Characterization of uracil-DNA glycosylase activity from Trypanosoma cruzi and its stimulation by AP endonuclease. Nucleic Acids Res 2001; 29:1549-55. [PMID: 11266557 PMCID: PMC31275 DOI: 10.1093/nar/29.7.1549] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The intracellular pathogen Trypanosoma cruzi is the etiological agent of Chagas' disease. We have isolated a full-length cDNA encoding uracil-DNA glycosylase (UDGase), a key enzyme involved in DNA repair, from this organism. The deduced protein sequence is highly conserved at the C-terminus of the molecule and shares key residues involved in binding or catalysis with most of the UDGases described so far, while the N-terminal part is highly variable. The gene is single copy and is located on a chromosome of approximately 1.9 Mb. A His-tagged recombinant protein was overexpressed, purified and used to raise polyclonal antibodies. Western blot analysis revealed the existence of a single UDGase species in parasite extracts. Using a specific ethidium bromide fluorescence assay, recombinant T.cruzi UDGase was shown to specifically excise uracil from DNA. The addition of both Leishmania major AP endonuclease and exonuclease III, the major AP endonuclease from Escherichia coli, produces stimulation of UDGase activity. This activation is specific for AP endonuclease and suggests functional communication between the two enzymes.
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Affiliation(s)
- M E Fárez-Vidal
- Instituto de Parasitología y Biomedicina 'López Neyra', Consejo Superior de Investigaciones Científicas, C/ Ventanilla 11, 18001 Granada, Spain
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11
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Montalvetti A, Peña-Díaz J, Hurtado R, Ruiz-Pérez LM, González-Pacanowska D. Characterization and regulation of Leishmania major 3-hydroxy-3-methylglutaryl-CoA reductase. Biochem J 2000; 349:27-34. [PMID: 10861207 PMCID: PMC1221116 DOI: 10.1042/0264-6021:3490027] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In eukaryotes the enzyme 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase catalyses the synthesis of mevalonic acid, a common precursor to all isoprenoid compounds. Here we report the isolation and overexpression of the gene coding for HMG-CoA reductase from Leishmania major. The protein from Leishmania lacks the membrane domain characteristic of eukaryotic cells but exhibits sequence similarity with eukaryotic reductases. Highly purified protein was achieved by ammonium sulphate precipitation followed by chromatography on hydroxyapatite. Kinetic parameters were determined for the protozoan reductase, obtaining K(m) values for the overall reaction of 40.3+/-5.8 microM for (R,S)-HMG-CoA and 81.4+/-5.3 microM for NADPH; V(max) was 33.55+/-1.8 units x mg(-1). Gel-filtration experiments suggested an apparent molecular mass of 184 kDa with subunits of 46 kDa. Finally, in order to achieve a better understanding of the role of this enzyme in trypanosomatids, the effect of possible regulators of isoprenoid biosynthesis in cultured promastigote cells was studied. Neither mevalonic acid nor serum sterols appear to modulate enzyme activity whereas incubation with lovastatin results in significant increases in the amount of reductase protein. Western- and Northern-blot analyses indicate that this activation is apparently performed via post-transcriptional control.
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MESH Headings
- Amino Acid Sequence
- Ammonium Sulfate/pharmacology
- Animals
- Blotting, Northern
- Blotting, Western
- Cell Membrane/metabolism
- Cells, Cultured
- Chromatography
- Chromatography, Gel
- Chromosome Mapping
- Durapatite/pharmacology
- Electrophoresis, Polyacrylamide Gel
- Gene Expression Regulation, Enzymologic
- Hydroxymethylglutaryl CoA Reductases/chemistry
- Hydroxymethylglutaryl CoA Reductases/genetics
- Hydroxymethylglutaryl CoA Reductases/isolation & purification
- Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacology
- Ketoconazole/pharmacology
- Kinetics
- Leishmania major/enzymology
- Lovastatin/pharmacology
- Mevalonic Acid/pharmacology
- Molecular Sequence Data
- Protein Structure, Tertiary
- RNA Processing, Post-Transcriptional
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
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Affiliation(s)
- A Montalvetti
- Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas, C/Ventanilla 11, 18001-Granada, Spain
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12
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Ginger ML, Prescott MC, Reynolds DG, Chance ML, Goad LJ. Utilization of leucine and acetate as carbon sources for sterol and fatty acid biosynthesis by Old and New World Leishmania species, Endotrypanum monterogeii and Trypanosoma cruzi. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:2555-66. [PMID: 10785375 DOI: 10.1046/j.1432-1327.2000.01261.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The relative roles of acetate and leucine in the provision of a carbon source for fatty acid and sterol biosynthesis in several trypanosomatid species were investigated using 14C- and 13C-labelled acetate, glucose and leucine as substrates. Promastigotes of Leishmania species synthesized a large proportion of their sterol from leucine. L. major (LV39), L. amazonensis and L. mexicana were the most efficient utilizers of leucine, producing at least 70-77% of their sterol from leucine; L. braziliensis, L. donovani and L. tropica apparently produced less sterol from leucine (23-36%) and L. major (LV561), L. adleri and L. panamamensis were intermediate, utilizing leucine to provide 51-58% of their sterol. In all the cases the balance of the sterol produced was apparently synthesized from carbon arising from acetate. The related trypanosomatid Endotrypanum monterogeii also produced a large amount (77%) of its sterol from leucine rather than acetate. By contrast Trypanosoma cruzi elaborated only 8% of its sterol from leucine and used acetate far more effectively than the Leishmania species for sterol biosynthesis. The fatty acid moieties of the triacylglycerols and phospholipids were produced from acetate. Leucine was also incorporated into the fatty acids to varying extents in the different organisms showing that leucine can also be metabolized in trypanosomatids to generate acetyl-CoA.
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Affiliation(s)
- M L Ginger
- School of Biological Sciences, Life Sciences Building, University of Liverpool, UK
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13
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Giordano W, Avalos J, Fernández-Martín R, Cerdá-Olmedo E, Domenech CE. Lovastatin inhibits the production of gibberellins but not sterol or carotenoid biosynthesis in Gibberella fujikuroi. MICROBIOLOGY (READING, ENGLAND) 1999; 145 ( Pt 10):2997-3002. [PMID: 10537222 DOI: 10.1099/00221287-145-10-2997] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Sterols, carotenoids and gibberellins are synthesized after the reduction of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) to mevalonate in different subcellular compartments of the fungus Gibberella fujikuroi. Lovastatin inhibits growth in many organisms, presumably because of the inhibition of the synthesis of essential terpenoids. However, in G. fujikuroi growth of the mycelia and sterol and carotenoid content were not affected by the presence of lovastatin. Nevertheless, lovastatin did inhibit the accumulation of gibberellins in the culture medium; this inhibition, however, was counteracted by the addition of mevalonate to the medium. The conversion of HMG-CoA to mevalonate in cell-free extracts was inhibited by 10 nM lovastatin. Since G. fujikuroi apparently possesses a single gene for HMG-CoA reductase, as shown by Southern hybridization and PCR amplification, it was concluded that the biosynthesis of sterols, carotenoids and gibberellins shares a single HMG-CoA reductase, but the respective subcellular compartments are differentially accessible to lovastatin.
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Affiliation(s)
- W Giordano
- Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Córdoba, Argentina
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Ginger ML, Chance ML, Goad LJ. Elucidation of carbon sources used for the biosynthesis of fatty acids and sterols in the trypanosomatid Leishmania mexicana. Biochem J 1999; 342 ( Pt 2):397-405. [PMID: 10455027 PMCID: PMC1220477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Sterols are necessary for the growth of trypanosomatid protozoans; sterol biosynthesis is a potential target for the use and development of drugs to treat the diseases caused by these organisms. This study has used (14)C-labelled substrates to investigate the carbon sources utilized by promastigotes and amastigotes of Leishmania mexicana for the production of sterol [mainly ergosta-5,7,24(24(1))-trien-3beta-ol] and the fatty acid moieties of the triacylglycerol (TAG) and phospholipid (PL) of the organism. The isoprenoid precursor mevalonic acid (MVA) was incorporated into the sterols, and the sterol precursor squalene, by the promastigotes of L. mexicana. However, acetate (the precursor to MVA in most organisms) was a very poor substrate for sterol production but was readily incorporated into the fatty acids of TAG and PL. Other substrates (glucose, palmitic acid, alanine, serine and isoleucine), which are metabolized to acetyl-CoA, were also very poor precursors to sterol but were incorporated into TAG and PL and gave labelling patterns of the lipids similar to those of acetate. In contrast, the amino acid leucine was the only substrate to be incorporated efficiently into the squalene and sterol of L. mexicana promastigotes. Quantitative measurements revealed that at least 70-80% of the sterol synthesized by the promastigotes of L. mexicana is produced from carbon provided by leucine metabolism. Studies with the amastigote form of L. mexicana showed that in this case leucine was again the major sterol precursor, whereas acetate was utilized for fatty acid production.
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Affiliation(s)
- M L Ginger
- School of Biological Sciences, Life Sciences Building, University of Liverpool, Liverpool L69 7ZB, U.K
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15
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Heise N, Opperdoes FR. Purification, localisation and characterisation of glucose-6-phosphate dehydrogenase of Trypanosoma brucei. Mol Biochem Parasitol 1999; 99:21-32. [PMID: 10215021 DOI: 10.1016/s0166-6851(98)00176-5] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Cell-fractionation and digitonin titration of procyclic trypomastigotes of Trypanosoma brucei, revealed that almost half of the total NADP+ -dependent glucose-6-phosphate dehydrogenase (G6PDH) activity, the first enzyme of the pentose phosphate pathway (PPP), is associated with glycosomes. The specific activity of G6PDH in the purified organelles was increased 4-fold relative to a total cell extract and showed latency. Moreover, in the absence of detergents this activity was totally resistant to the action of trypsin. The cytosolic counterpart was neither latent, nor was it resistant to trypsin. Both cytosolic and glycosomal G6PDH activities behaved identically on phenyl-, CM-, heparin-, and Affigel-blue-Sepharose columns. Both isoenzymes had a subunit Mr of 62 000 and an isoelectric point of 6.85, while kinetic studies carried out on the partially purified G6PDH from both cell compartments did not reveal any differences. The purified enzyme had an apparent Km of 138 and 5.3 microM for glucose 6-phosphate (G6P), and for NADP+, respectively, and had a specific activity of 14 micromol. (min mg of protein)(-1). We conclude that while in procyclic stages of T. brucei G6PDH activity is present in two different cell compartments, i.e. the cytosol and the glycosomes, these two activities most likely represent one and the same isoenzyme.
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Affiliation(s)
- N Heise
- Research Unit for Tropical Diseases, Christian de Duve Institute of Cellular Pathology (ICP) and Laboratory of Biochemistry, Catholic University of Louvain, Brussels, Belgium
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Concepcion JL, Gonzalez-Pacanowska D, Urbina JA. 3-Hydroxy-3-methyl-glutaryl-CoA reductase in Trypanosoma (Schizotrypanum) cruzi: subcellular localization and kinetic properties. Arch Biochem Biophys 1998; 352:114-20. [PMID: 9521823 DOI: 10.1006/abbi.1998.0577] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The subcellular localization of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase, which catalyzes the first committed step of the mevalonate pathway, was investigated in Trypanosoma cruzi epimastigotes using well-established cell fractionation procedures. It was found that ca. 80% of the activity of the enzyme was associated with the glycosomes, microbody-like organelles unique to kinetoplastid protozoa which contain most of the enzymes of the glycolytic pathway, while the rest of the activity was found in the soluble (cytoplasmatic) fraction, with almost no activity associated with microsomes. The glycosome-associated enzyme is not membrane-bound as it was recovered quantitatively in the aqueous phase of the biphasic system formed by Triton X-114 at 30 degrees C. Studies with digitonin-permeabilized intact epimastigotes demonstrated the presence of two pools of soluble HMG-CoA reductase in these cells, associated to the cytoplasmic and glycosomal compartments. Steady-state kinetic studies of the glycosome-associated enzyme indicated classical Michaelis-Menten behavior with Km,app (HMG-CoA) 28 +/- 3 microM, Km,app (NADPH) 37 +/- 4 microM, and Vm,app 3.9 +/- 0.2 nmol/min mg protein; the transition-state analog lovastatin behaved as a competitive inhibitor with respect to HMG-CoA with Kis 23 nM and a noncompetitive inhibitor toward NADPH with Kii 29 nM. The results are in complete agreement with recent gene cloning and expression studies which showed that T. cruzi HMG-CoA reductase lacks the NH2-terminal membrane-spanning sequence. This is the first demonstration of a soluble eukaryotic HMG-CoA reductase and also the first report on the presence of an enzyme of the isoprenoid biosynthesis pathway in glycosomes.
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Affiliation(s)
- J L Concepcion
- Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela
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