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Salari S, Bamorovat M, Sharifi I, Almani PGN. Global distribution of treatment resistance gene markers for leishmaniasis. J Clin Lab Anal 2022; 36:e24599. [PMID: 35808933 PMCID: PMC9396204 DOI: 10.1002/jcla.24599] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 06/19/2022] [Accepted: 06/28/2022] [Indexed: 01/02/2023] Open
Abstract
Background Pentavalent antimonials (Sb(V)) such as meglumine antimoniate (Glucantime®) and sodium stibogluconate (Pentostam®) are used as first‐line treatments for leishmaniasis, either alone or in combination with second‐line drugs such as amphotericin B (Amp B), miltefosine (MIL), methotrexate (MTX), or cryotherapy. Therapeutic aspects of these drugs are now challenged because of clinical resistance worldwide. Methods We reviewedthe recent original studies were assessed by searching in electronic databases such as Scopus, Pubmed, Embase, and Web of Science. Results Studies on molecular biomarkers involved in drug resistance are essential for monitoring the disease. We reviewed genes and mechanisms of resistance to leishmaniasis, and the geographical distribution of these biomarkers in each country has also been thoroughly investigated. Conclusion Due to the emergence of resistant genes mainly in anthroponotic Leishmania species such as L. donovani and L. tropica, as the causative agents of ACL and AVL, respectively, selection of an appropriate treatment modality is essential. Physicians should be aware of the presence of such resistance for the selection of proper treatment modalities in endemic countries.
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Affiliation(s)
- Samira Salari
- Medical Mycology and Bacteriology Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Mehdi Bamorovat
- Leishmaniasis Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Iraj Sharifi
- Leishmaniasis Research Center, Kerman University of Medical Sciences, Kerman, Iran
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Combined gene deletion of dihydrofolate reductase-thymidylate synthase and pteridine reductase in Leishmania infantum. PLoS Negl Trop Dis 2021; 15:e0009377. [PMID: 33905412 PMCID: PMC8104401 DOI: 10.1371/journal.pntd.0009377] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 05/07/2021] [Accepted: 04/11/2021] [Indexed: 12/13/2022] Open
Abstract
Our understanding of folate metabolism in Leishmania has greatly benefited from studies of resistance to the inhibitor methotrexate (MTX). Folates are reduced in Leishmania by the bifunctional dihydrofolate reductase thymidylate synthase (DHFR-TS) and by pteridine reductase (PTR1). To further our understanding of folate metabolism in Leishmania, a Cos-seq genome-wide gain of function screen was performed against MTX and against the two thymidylate synthase (TS) inhibitors 5-fluorouracil and pemetrexed. The screen revealed DHFR-TS and PTR1 but also the nucleoside transporter NT1 and one hypothetical gene derived from chromosome 31. For MTX, the concentration of folate in the culture medium affected the enrichment pattern for genes retrieved by Cos-seq. We generated a L. infantum DHFR-TS null mutant that was thymidine auxotroph, a phenotype that could be rescued by the addition of thymidine or by transfection of the flavin dependent bacterial TS gene ThyX. In these DHFR-TS null mutants it was impossible to obtain a chromosomal null mutant of PTR1 except if DHFR-TS or PTR1 were provided episomally. The transfection of ThyX however did not allow the elimination of PTR1 in a DHFR-TS null mutant. Leishmania can survive without copies of either DHFR-TS or PTR1 but not without both. Provided that our results observed with the insect stage parasites are also replicated with intracellular parasites, it would suggest that antifolate therapy in Leishmania would only work if both DHFR-TS and PTR1 would be targeted simultaneously. The protozoan parasite Leishmania is auxotroph for folate and unconjugated pterins and salvages both from the mammalian host. Two enzymes of the folate metabolism pathway, namely the bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) and the pteridine reductase 1 (PTR1), are being evaluated for drug discovery and repurposing of existing anti-metabolites. Despite their apparent potential, development of DHFR-TS and PTR1 targeted chemotherapy against Leishmania is still awaiting. Here we revisited folate metabolism at the genomic level and report on the identification of known resistance genes alongside some new ones. Through gene disruption studies we found that L. infantum DHFR-TS null mutants are thymidine auxotroph and that these can be rescued by the bacterial flavin dependent thymidylate synthase ThyX. We also found that PTR1 is essential in the absence of a functional DHFR-TS even in the presence of ThyX or thymidine supplementation, indicating the essential role of reduced pterins or folate beyond thymidine synthesis. This study indicates that simultaneous targeting of DHFR-TS and PTR1 will be required for the development of anti-folate chemotherapy against Leishmania.
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Laloo AE, Wei J, Wang D, Narayanasamy S, Vanwonterghem I, Waite D, Steen J, Kaysen A, Heintz-Buschart A, Wang Q, Schulz B, Nouwens A, Wilmes P, Hugenholtz P, Yuan Z, Bond PL. Mechanisms of Persistence of the Ammonia-Oxidizing Bacteria Nitrosomonas to the Biocide Free Nitrous Acid. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:5386-5397. [PMID: 29620869 DOI: 10.1021/acs.est.7b04273] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Free nitrous acid (FNA) exerts a broad range of antimicrobial effects on bacteria, although susceptibility varies considerably among microorganisms. Among nitrifiers found in activated sludge of wastewater treatment processes (WWTPs), nitrite-oxidizing bacteria (NOB) are more susceptible to FNA compared to ammonia-oxidizing bacteria (AOB). This selective inhibition of NOB over AOB in WWTPs bypasses nitrate production and improves the efficiency and costs of the nitrogen removal process in both the activated sludge and anaerobic ammonium oxidation (Anammox) system. However, the molecular mechanisms governing this atypical tolerance of AOB to FNA have yet to be understood. Herein we investigate the varying effects of the antimicrobial FNA on activated sludge containing AOB and NOB using an integrated metagenomics and label-free quantitative sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH-MS) metaproteomic approach. The Nitrosomonas genus of AOB, on exposure to FNA, maintains internal homeostasis by upregulating a number of known oxidative stress enzymes, such as pteridine reductase and dihydrolipoyl dehydrogenase. Denitrifying enzymes were upregulated on exposure to FNA, suggesting the detoxification of nitrite to nitric oxide. Interestingly, proteins involved in stress response mechanisms, such as DNA and protein repair enzymes, phage prevention proteins, and iron transport proteins, were upregulated on exposure to FNA. In addition enzymes involved in energy generation were also upregulated on exposure to FNA. The total proteins specifically derived from the NOB genus Nitrobacter was low and, as such, did not allow for the elucidation of the response mechanism to FNA exposure. These findings give us an understanding of the adaptive mechanisms of tolerance within the AOB Nitrosomonas to the biocidal agent FNA.
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Affiliation(s)
- Andrew E Laloo
- Advanced Water Management Centre , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
| | - Justin Wei
- Advanced Water Management Centre , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
| | - Dongbo Wang
- College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education , Hunan University , Changsa 410082 , China
| | - Shaman Narayanasamy
- Luxembourg Centre for Systems Biomedicine , Université du Luxembourg , L-4362 Esch-sur-Alzette , Luxembourg
| | - Inka Vanwonterghem
- Australian Centre for Ecogenomics (ACE), School of Chemistry and Molecular Bioscience , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
| | - David Waite
- Australian Centre for Ecogenomics (ACE), School of Chemistry and Molecular Bioscience , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
| | - Jason Steen
- Australian Centre for Ecogenomics (ACE), School of Chemistry and Molecular Bioscience , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
| | - Anne Kaysen
- Luxembourg Centre for Systems Biomedicine , Université du Luxembourg , L-4362 Esch-sur-Alzette , Luxembourg
| | - Anna Heintz-Buschart
- Luxembourg Centre for Systems Biomedicine , Université du Luxembourg , L-4362 Esch-sur-Alzette , Luxembourg
| | - Qilin Wang
- Griffith School of Engineering & Centre for Clean Environment and Energy , Griffith University , Nathan , QLD 4111 , Australia
| | - Benjamin Schulz
- School of Chemistry and Molecular Biosciences , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
| | - Amanda Nouwens
- School of Chemistry and Molecular Biosciences , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
| | - Paul Wilmes
- Luxembourg Centre for Systems Biomedicine , Université du Luxembourg , L-4362 Esch-sur-Alzette , Luxembourg
| | - Philip Hugenholtz
- Australian Centre for Ecogenomics (ACE), School of Chemistry and Molecular Bioscience , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
| | - Zhiguo Yuan
- Advanced Water Management Centre , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
| | - Philip L Bond
- Advanced Water Management Centre , The University of Queensland , St. Lucia , Brisbane , QLD 4072 , Australia
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Oxidative Stress-Mediated Overexpression of Uracil DNA Glycosylase in Leishmania donovani Confers Tolerance against Antileishmanial Drugs. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:4074357. [PMID: 29636843 PMCID: PMC5845521 DOI: 10.1155/2018/4074357] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/01/2017] [Accepted: 12/19/2017] [Indexed: 01/09/2023]
Abstract
Leishmania donovani is an intracellular protozoan parasite that causes endemic tropical disease visceral leishmaniasis (VL). Present drugs used against this fatal disease are facing resistance and toxicity issues. Survival of leishmania inside the host cells depends on the parasite's capacity to cope up with highly oxidative environment. Base excision repair (BER) pathway in L. donovani remains unexplored. We studied uracil DNA glycosylase (UNG), the key enzyme involved in BER pathway, and found that the glycosylase activity of recombinant LdUNG (Leishmania donovani UNG) expressed in E. coli is in sync with the activity of the parasite lysate under different reaction conditions. Overexpression of UNG in the parasite enhances its tolerance towards various agents which produce reactive oxygen species (ROS) and shows a higher infectivity in macrophages. Surprisingly, exposure of parasite to amphotericin B and sodium antimony gluconate upregulates the expression of UNG. Further, we found that the drug resistant parasites isolated from VL patients show higher expression of UNG. Mechanisms of action of some currently used drugs include accumulation of ROS. Our findings strongly suggest that targeting LdUNG would be an attractive therapeutic strategy as well as potential measure to tackle the problem of drug resistance in the treatment of leishmaniasis.
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Laffitte MCN, Leprohon P, Hainse M, Légaré D, Masson JY, Ouellette M. Chromosomal Translocations in the Parasite Leishmania by a MRE11/RAD50-Independent Microhomology-Mediated End Joining Mechanism. PLoS Genet 2016; 12:e1006117. [PMID: 27314941 PMCID: PMC4912120 DOI: 10.1371/journal.pgen.1006117] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 05/20/2016] [Indexed: 01/15/2023] Open
Abstract
The parasite Leishmania often relies on gene rearrangements to survive stressful environments. However, safeguarding a minimum level of genome integrity is important for cell survival. We hypothesized that maintenance of genomic integrity in Leishmania would imply a leading role of the MRE11 and RAD50 proteins considering their role in DNA repair, chromosomal organization and protection of chromosomes ends in other organisms. Attempts to generate RAD50 null mutants in a wild-type background failed and we provide evidence that this gene is essential. Remarkably, inactivation of RAD50 was possible in a MRE11 null mutant that we had previously generated, providing good evidence that RAD50 may be dispensable in the absence of MRE11. Inactivation of the MRE11 and RAD50 genes led to a decreased frequency of homologous recombination and analysis of the null mutants by whole genome sequencing revealed several chromosomal translocations. Sequencing of the junction between translocated chromosomes highlighted microhomology sequences at the level of breakpoint regions. Sequencing data also showed a decreased coverage at subtelomeric locations in many chromosomes in the MRE11-/-RAD50-/- parasites. This study demonstrates an MRE11-independent microhomology-mediated end-joining mechanism and a prominent role for MRE11 and RAD50 in the maintenance of genomic integrity. Moreover, we suggest the possible involvement of RAD50 in subtelomeric regions stability. The parasite Leishmania relies on gene rearrangements to survive stressful conditions. However, maintaining a minimum level of genomic integrity is crucial for cell survival. Studies in other organisms have provided evidence that the DNA repair proteins MRE11 and RAD50 are involved in chromosomes organization, protection of chromosomes ends and therefore in the maintenance of genomic integrity. In this manuscript, we present the conditional inactivation of the Leishmania infantum RAD50 gene that was only possible in MRE11 deficient cells and suggest the genetic background is crucial for RAD50 inactivation. We demonstrate the occurrence of chromosomal translocations in the MRE11 and RAD50 deficient cells and described a MRE11-independent microhomology-mediated end-joining mechanism at the level of translocation breakpoints. We also suggest a possible involvement of RAD50 in subtelomeric regions stability. Our results highlight that both MRE11 and RAD50 are important for the maintenance of genomic integrity in Leishmania.
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Affiliation(s)
| | - Philippe Leprohon
- Centre de Recherche en Infectiologie, CRCHU de Québec, Québec City, Québec, Canada
| | - Maripier Hainse
- Genome Stability Laboratory, CRCHU de Québec, Pavillon HDQ Oncology axis, Québec City, Québec, Canada
| | - Danielle Légaré
- Centre de Recherche en Infectiologie, CRCHU de Québec, Québec City, Québec, Canada
| | - Jean-Yves Masson
- Genome Stability Laboratory, CRCHU de Québec, Pavillon HDQ Oncology axis, Québec City, Québec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Centre de recherche sur le Cancer, Université Laval, Québec City, Québec, Canada
| | - Marc Ouellette
- Centre de Recherche en Infectiologie, CRCHU de Québec, Québec City, Québec, Canada
- * E-mail:
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Roy G, Ouellette M. Inactivation of the cytosolic and mitochondrial serine hydroxymethyl transferase genes in Leishmania major. Mol Biochem Parasitol 2016; 204:106-110. [PMID: 26868981 DOI: 10.1016/j.molbiopara.2016.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 01/11/2016] [Accepted: 02/05/2016] [Indexed: 11/28/2022]
Abstract
Leishmania has two serine hydroxylmethyl transferase (SHMT) genes, one coding for a cytosolic and the other for a mitochondrial enzyme. Trypanosoma cruzi has only the gene coding for the cytosolic enzyme and Trypanosoma brucei has no SHMT. We tested whether these genes were dispensable for growth in Leishmania major. By gene inactivation we succeeded in generating three cells lines one without the cytosolic cSHMT, one without the mitochondrial mSHMT, and finally one L. major line without any SHMT. SHMT is thus dispensable for growth of Leishmania in rich medium. The ability of the various shmt null mutants to grow in defined medium was tested and the growth of the shmt null mutant was dependent on the presence of serine. Overall this work has shown that SHMT is dispensable for Leishmania growth but it may be necessary when growing in environments poor in serine.
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Affiliation(s)
- Gaétan Roy
- Centre de Recherche en Infectiologie de l'Université Laval et Centre de Recherche du CHU de Québec, Canada
| | - Marc Ouellette
- Centre de Recherche en Infectiologie de l'Université Laval et Centre de Recherche du CHU de Québec, Canada; Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada.
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de Souza Moreira D, Ferreira RF, Murta SMF. Molecular characterization and functional analysis of pteridine reductase in wild-type and antimony-resistant Leishmania lines. Exp Parasitol 2015; 160:60-6. [PMID: 26689884 DOI: 10.1016/j.exppara.2015.12.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 09/21/2015] [Accepted: 12/09/2015] [Indexed: 01/24/2023]
Abstract
Pteridine reductase (PTR1) is an NADPH-dependent reductase that participates in the salvage of pteridines, which are essential to maintain growth of Leishmania. In this study, we performed the molecular characterization of ptr1 gene in wild-type (WTS) and SbIII-resistant (SbR) lines from Leishmania guyanensis (Lg), Leishmania amazonensis (La), Leishmania braziliensis (Lb) and Leishmania infantum (Li), evaluating the chromosomal location, mRNA levels of the ptr1 gene and PTR1 protein expression. PFGE results showed that the ptr1 gene is located in a 797 kb chromosomal band in all Leishmania lines analyzed. Interestingly, an additional chromosomal band of 1070 kb was observed only in LbSbR line. Northern blot results showed that the levels of ptr1 mRNA are increased in the LgSbR, LaSbR and LbSbR lines. Western blot assays using the polyclonal anti-LmPTR1 antibody demonstrated that PTR1 protein is more expressed in the LgSbR, LaSbR and LbSbR lines compared to their respective WTS counterparts. Nevertheless, no difference in the level of mRNA and protein was observed between the LiWTS and LiSbR lines. Functional analysis of PTR1 enzyme was performed to determine whether the overexpression of ptr1 gene in the WTS L. braziliensis and L. infantum lines would change the SbIII-resistance phenotype of transfected parasites. Western blot results showed that the expression level of PTR1 protein was increased in the transfected parasites compared to the non-transfected ones. IC50 analysis revealed that the overexpression of ptr1 gene in the WTS L. braziliensis line increased 2-fold the SbIII-resistance phenotype compared to the non-transfected counterpart. Furthermore, the overexpression of ptr1 gene in the WTS L. infantum line did not change the SbIII-resistance phenotype. These results suggest that the PTR1 enzyme may be implicated in the SbIII-resistance phenotype in L. braziliensis line.
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Affiliation(s)
- Douglas de Souza Moreira
- Laboratório de Parasitologia Celular e Molecular, Centro de Pesquisas René Rachou CPqRR/Fiocruz, Av. Augusto de Lima 1715, CEP 30190-002, Belo Horizonte, MG, Brazil
| | - Rafael Fernandes Ferreira
- Laboratório de Parasitologia Celular e Molecular, Centro de Pesquisas René Rachou CPqRR/Fiocruz, Av. Augusto de Lima 1715, CEP 30190-002, Belo Horizonte, MG, Brazil
| | - Silvane M F Murta
- Laboratório de Parasitologia Celular e Molecular, Centro de Pesquisas René Rachou CPqRR/Fiocruz, Av. Augusto de Lima 1715, CEP 30190-002, Belo Horizonte, MG, Brazil.
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Laffitte MCN, Genois MM, Mukherjee A, Légaré D, Masson JY, Ouellette M. Formation of linear amplicons with inverted duplications in Leishmania requires the MRE11 nuclease. PLoS Genet 2014; 10:e1004805. [PMID: 25474106 PMCID: PMC4256157 DOI: 10.1371/journal.pgen.1004805] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 10/06/2014] [Indexed: 11/22/2022] Open
Abstract
Extrachromosomal DNA amplification is frequent in the protozoan parasite Leishmania selected for drug resistance. The extrachromosomal amplified DNA is either circular or linear, and is formed at the level of direct or inverted homologous repeated sequences that abound in the Leishmania genome. The RAD51 recombinase plays an important role in circular amplicons formation, but the mechanism by which linear amplicons are formed is unknown. We hypothesized that the Leishmania infantum DNA repair protein MRE11 is required for linear amplicons following rearrangements at the level of inverted repeats. The purified LiMRE11 protein showed both DNA binding and exonuclease activities. Inactivation of the LiMRE11 gene led to parasites with enhanced sensitivity to DNA damaging agents. The MRE11−/− parasites had a reduced capacity to form linear amplicons after drug selection, and the reintroduction of an MRE11 allele led to parasites regaining their capacity to generate linear amplicons, but only when MRE11 had an active nuclease activity. These results highlight a novel MRE11-dependent pathway used by Leishmania to amplify portions of its genome to respond to a changing environment. Extrachromosomal DNA amplification is frequent in the human protozoan parasite Leishmania when challenged with drug or other stressful conditions. DNA amplicons, either circular or linear, are formed by recombination between direct or inverted repeats spread throughout the genome of the parasite. The recombinase RAD51 is involved in the formation of circular amplicons, but the mechanism by which linear amplicons are formed is still unknown in this parasite. Studies in other organisms have provided some evidence that a DNA break is required for linear amplifications, and that the DNA repair protein MRE11 can be involved in this process. In this work, we present our biochemical, cellular and molecular characterization of the Leishmania infantum MRE11 orthologue and provide evidence that this nuclease is involved in the formation of linear amplicons in Leishmania. Our results highlight a novel MRE11-dependent pathway used by Leishmania to amplify portions of its genome to respond to a changing environment.
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Affiliation(s)
| | - Marie-Michelle Genois
- Centre de Recherche en Infectiologie du CHU de Québec, Quebec City, Québec, Canada
- Genome Stability Laboratory, CHU de Quebec Research Center, HDQ Pavillon, Oncology Axis, Quebec City, Québec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec City, Québec, Canada
| | - Angana Mukherjee
- Centre de Recherche en Infectiologie du CHU de Québec, Quebec City, Québec, Canada
| | - Danielle Légaré
- Centre de Recherche en Infectiologie du CHU de Québec, Quebec City, Québec, Canada
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Quebec Research Center, HDQ Pavillon, Oncology Axis, Quebec City, Québec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec City, Québec, Canada
| | - Marc Ouellette
- Centre de Recherche en Infectiologie du CHU de Québec, Quebec City, Québec, Canada
- * E-mail:
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Xu W, Hsu FF, Baykal E, Huang J, Zhang K. Sterol biosynthesis is required for heat resistance but not extracellular survival in leishmania. PLoS Pathog 2014; 10:e1004427. [PMID: 25340392 PMCID: PMC4207814 DOI: 10.1371/journal.ppat.1004427] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 08/27/2014] [Indexed: 12/25/2022] Open
Abstract
Sterol biosynthesis is a crucial pathway in eukaryotes leading to the production of cholesterol in animals and various C24-alkyl sterols (ergostane-based sterols) in fungi, plants, and trypanosomatid protozoa. Sterols are important membrane components and precursors for the synthesis of powerful bioactive molecules, including steroid hormones in mammals. Their functions in pathogenic protozoa are not well characterized, which limits the development of sterol synthesis inhibitors as drugs. Here we investigated the role of sterol C14α-demethylase (C14DM) in Leishmania parasites. C14DM is a cytochrome P450 enzyme and the primary target of azole drugs. In Leishmania, genetic or chemical inactivation of C14DM led to a complete loss of ergostane-based sterols and accumulation of 14-methylated sterols. Despite the drastic change in lipid composition, C14DM-null mutants (c14dm(-)) were surprisingly viable and replicative in culture. They did exhibit remarkable defects including increased membrane fluidity, failure to maintain detergent resistant membrane fraction, and hypersensitivity to heat stress. These c14dm(-) mutants showed severely reduced virulence in mice but were highly resistant to itraconazole and amphotericin B, two drugs targeting sterol synthesis. Our findings suggest that the accumulation of toxic sterol intermediates in c14dm(-) causes strong membrane perturbation and significant vulnerability to stress. The new knowledge may help improve the efficacy of current drugs against pathogenic protozoa by exploiting the fitness loss associated with drug resistance.
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Affiliation(s)
- Wei Xu
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - Fong-Fu Hsu
- Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Eda Baykal
- Department of Physics, Texas Tech University, Lubbock, Texas, United States of America
| | - Juyang Huang
- Department of Physics, Texas Tech University, Lubbock, Texas, United States of America
| | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America
- * E-mail:
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Proteomic analysis of metacyclogenesis in Leishmania infantum wild-type and PTR1 null mutant. EUPA OPEN PROTEOMICS 2014. [DOI: 10.1016/j.euprot.2014.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Smirlis D, Soares MBP. Selection of molecular targets for drug development against trypanosomatids. Subcell Biochem 2014; 74:43-76. [PMID: 24264240 DOI: 10.1007/978-94-007-7305-9_2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Trypanosomatid parasites are a group of flagellated protozoa that includes the genera Leishmania and Trypanosoma, which are the causative agents of diseases (leishmaniases, sleeping sickness and Chagas disease) that cause considerable morbidity and mortality, affecting more than 27 million people worldwide. Today no effective vaccines for the prevention of these diseases exist, whereas current chemotherapy is ineffective, mainly due to toxic side effects of current drugs and to the emergence of drug resistance and lack of cost effectiveness. For these reasons, rational drug design and the search of good candidate drug targets is of prime importance. The search for drug targets requires a multidisciplinary approach. To this end, the completion of the genome project of many trypanosomatid species gives a vast amount of new information that can be exploited for the identification of good drug candidates with a prediction of "druggability" and divergence from mammalian host proteins. In addition, an important aspect in the search for good drug targets is the "target identification" and evaluation in a biological pathway, as well as the essentiality of the gene in the mammalian stage of the parasite, which is provided by basic research and genetic and proteomic approaches. In this chapter we will discuss how these bioinformatic tools and experimental evaluations can be integrated for the selection of candidate drug targets, and give examples of metabolic and signaling pathways in the parasitic protozoa that can be exploited for rational drug design.
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Sansom FM, Tang L, Ralton JE, Saunders EC, Naderer T, McConville MJ. Leishmania major methionine sulfoxide reductase A is required for resistance to oxidative stress and efficient replication in macrophages. PLoS One 2013; 8:e56064. [PMID: 23437085 PMCID: PMC3577802 DOI: 10.1371/journal.pone.0056064] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 01/04/2013] [Indexed: 12/25/2022] Open
Abstract
Leishmania are protozoan parasites that proliferate within the phagolysome of mammalian macrophages. While a number of anti-oxidant systems in these parasites have been shown to protect against endogenous as well as host-generated reactive oxygen species, the potential role of enzymes involved in the repair of oxidatively damaged proteins remains uncharacterized. The Leishmania spp genomes encode a single putative methionine sulfoxide reductase (MsrA) that could have a role in reducing oxidized free and proteinogenic methionine residues. A GFP-fusion of L. major MsrA was shown to have a cytoplasmic localization by immunofluorescence microscopy and subcellular fractionation. An L. major msrA null mutant, generated by targeted replacement of both chromosomal allelles, was viable in rich medium but was unable to reduce exogenous methionine sulfoxide when cultivated in the presence of this amino acid, indicating that msrA encodes a functional MsrA. The ΔmsrA mutant exhibited increased sensitivity to H2O2 compared to wild type parasites and was unable to proliferate normally in macrophages. Wild type sensitivity to H2O2 and infectivity in macrophages was restored by complementation of the mutant with a plasmid encoding MsrA. Unexpectedly, the ΔmsrA mutant was able to induce normal lesions in susceptible BALB/c indicating that this protein is not essential for pathogenesis in vivo. Our results suggest that Leishmania MsrA contributes to the anti-oxidative defences of these parasites, but that complementary oxidative defence mechansims are up-regulated in lesion amastigotes.
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Affiliation(s)
- Fiona M. Sansom
- Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
- Faculty of Veterinary Science, University of Melbourne, Parkville, Victoria, Australia
| | - Leonie Tang
- Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
| | - Julie E. Ralton
- Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
| | - Eleanor C. Saunders
- Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
| | - Thomas Naderer
- Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
| | - Malcolm J. McConville
- Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
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Coelho AC, Leprohon P, Ouellette M. Generation of Leishmania hybrids by whole genomic DNA transformation. PLoS Negl Trop Dis 2012; 6:e1817. [PMID: 23029579 PMCID: PMC3447969 DOI: 10.1371/journal.pntd.0001817] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 08/01/2012] [Indexed: 11/19/2022] Open
Abstract
Genetic exchange is a powerful tool to study gene function in microorganisms. Here, we tested the feasibility of generating Leishmania hybrids by electroporating genomic DNA of donor cells into recipient Leishmania parasites. The donor DNA was marked with a drug resistance marker facilitating the selection of DNA transfer into the recipient cells. The transferred DNA was integrated exclusively at homologous locus and was as large as 45 kb. The independent generation of L. infantum hybrids with L. major sequences was possible for several chromosomal regions. Interfering with the mismatch repair machinery by inactivating the MSH2 gene enabled an increased efficiency of recombination between divergent sequences, hence favouring the selection of hybrids between species. Hybrids were shown to acquire the phenotype derived from the donor cells, as demonstrated for the transfer of drug resistance genes from L. major into L. infantum. The described method is a first step allowing the generation of in vitro hybrids for testing gene functions in a natural genomic context in the parasite Leishmania.
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Affiliation(s)
| | | | - Marc Ouellette
- Centre de Recherche en Infectiologie, Université Laval, Québec, Canada
- * E-mail:
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14
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Gour JK, Kumar V, Singh N, Bajpai S, Pandey HP, Singh RK. Identification of Th1-responsive leishmanial excretory-secretory antigens (LESAs). Exp Parasitol 2012; 132:355-61. [PMID: 22955114 DOI: 10.1016/j.exppara.2012.04.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 03/27/2012] [Accepted: 04/12/2012] [Indexed: 12/11/2022]
Abstract
The objective of this study was to evaluate the immunomodulatory role of leishmanial excretory-secretory antigens (LESAs) released by in vitro cultured protozoan parasite Leishmania donovani promastigotes. A total of seventeen excretory-secretory proteins of relative molecular weights 11, 13, 16, 18, 21, 23, 26, 29, 33, 35, 42, 51, 54, 58, 64, 70 and 80 kDa were identified. The proteins were divided into five fractions (F1-F5) along with the whole LESAs, these fractions were evaluated for their potential antigenicity to induce macrophage effector functions, lymphoproliferation and cytokines production capabilities. Two fractions, F1 (11, 13 and 16 kDa) and F3 (26, 29 and 33 kDa), were found to be highly immunogenic as they significantly induced NADPH oxidase and SOD activities as well as NOx, TNF-α, IFN-γ and IL-12 production in stimulated RAW 264.7 macrophages. Further, these antigens also induced significant proliferation of human peripheral blood mononuclear cells along with increased production of IFN-γ and IL-12. The results strongly suggest the potential role of LESAs in the modulation of macrophage effector functions and Th1 immune response that gives a hope to develop potent vaccine for visceral leishmaniasis.
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Affiliation(s)
- Jalaj K Gour
- Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
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15
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Involvement of the Leishmania donovani virulence factor A2 in protection against heat and oxidative stress. Exp Parasitol 2012; 132:109-15. [PMID: 22691540 DOI: 10.1016/j.exppara.2012.06.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 05/31/2012] [Accepted: 06/01/2012] [Indexed: 02/02/2023]
Abstract
Leishmania is an obligate intracellular protozoan parasite that infects cells of the reticulo-endothelial system. Host defences against Leishmania include fever and oxidant production, and the parasite has developed a number of defence mechanisms to neutralize the host response. The Leishmania donovani A2 family of proteins has been shown to be essential for survival in mammalian visceral organs. Here we provide evidence that A2 proteins protect the parasite against host defences, namely heat stress (fever) and oxidative stress. A2 is however unable to protect the cells from endoplasmic reticulum stress induced by dithiothreitol. To downregulate A2 protein expression, L. donovani was transfected with an A2 antisense RNA expressing-vector, resulting in significant reduction of A2 levels. The resulting A2-deficient cells were more sensitive to heat shock and this was associated with increased production of internal oxidants during heat shock. Moreover, axenic amastigotes with downregulated A2 expression had increased internal oxidants and decreased viability following treatment with hydrogen peroxide or a nitric oxide donor when compared to control cells. Overall, these results suggest that A2 protects L. donovani from a variety of stresses, thereby allowing it to survive in the internal organs of the mammalian host and to cause visceral disease.
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Coelho AC, Boisvert S, Mukherjee A, Leprohon P, Corbeil J, Ouellette M. Multiple mutations in heterogeneous miltefosine-resistant Leishmania major population as determined by whole genome sequencing. PLoS Negl Trop Dis 2012; 6:e1512. [PMID: 22348164 PMCID: PMC3279362 DOI: 10.1371/journal.pntd.0001512] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 12/20/2011] [Indexed: 01/11/2023] Open
Abstract
Background Miltefosine (MF) is the first oral compound used in the chemotherapy against leishmaniasis. Since the mechanism of action of this drug and the targets of MF in Leishmania are unclear, we generated in a step-by-step manner Leishmania major promastigote mutants highly resistant to MF. Two of the mutants were submitted to a short-read whole genome sequencing for identifying potential genes associated with MF resistance. Methods/Principal Findings Analysis of the genome assemblies revealed several independent point mutations in a P-type ATPase involved in phospholipid translocation. Mutations in two other proteins—pyridoxal kinase and α-adaptin like protein—were also observed in independent mutants. The role of these proteins in the MF resistance was evaluated by gene transfection and gene disruption and both the P-type ATPase and pyridoxal kinase were implicated in MF susceptibility. The study also highlighted that resistance can be highly heterogeneous at the population level with individual clones derived from this population differing both in terms of genotypes but also susceptibility phenotypes. Conclusions/Significance Whole genome sequencing was used to pinpoint known and new resistance markers associated with MF resistance in the protozoan parasite Leishmania. The study also demonstrated the polyclonal nature of a resistant population with individual cells with varying susceptibilities and genotypes. Leishmania spp. are parasitic protozoa responsible for a spectrum of diseases known as leishmaniasis. There are few drugs available for the treatment of these diseases, and miltefosine is the first oral drug used in treatment of visceral leishmaniasis, a form of the disease that can be lethal if not treated. In this study, we seek to understand the mechanism of action and identify targets of the drug by generating promastigote mutants highly resistant to miltefosine. Two independent mutants were submitted to short read whole genome sequencing. Genome analysis of these mutants has permitted us to identify point mutations in three genes (P-type ATPase, pyridoxal kinase and α-adaptin like protein) that were also present in other independent miltefosine resistant mutants. Some of the new genes identified here could be useful as potential markers for miltefosine resistance in Leishmania. Moreover, our approach has permitted us to highlight that resistance can be highly heterogeneous at the population level with individual clones derived from this population differing both in terms of genotypes but also susceptibility phenotypes. This may have practical applications while studying resistance.
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Affiliation(s)
- Adriano C. Coelho
- Centre de Recherche en Infectiologie, Université Laval, Québec, Canada
| | | | - Angana Mukherjee
- Centre de Recherche en Infectiologie, Université Laval, Québec, Canada
| | - Philippe Leprohon
- Centre de Recherche en Infectiologie, Université Laval, Québec, Canada
| | - Jacques Corbeil
- Centre de Recherche en Infectiologie, Université Laval, Québec, Canada
| | - Marc Ouellette
- Centre de Recherche en Infectiologie, Université Laval, Québec, Canada
- * E-mail:
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17
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McConville MJ, Naderer T. Metabolic pathways required for the intracellular survival of Leishmania. Annu Rev Microbiol 2012; 65:543-61. [PMID: 21721937 DOI: 10.1146/annurev-micro-090110-102913] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Leishmania spp. are sandfly-transmitted parasitic protozoa that cause a spectrum of important diseases and lifelong chronic infections in humans. In the mammalian host, these parasites proliferate within acidified vacuoles in several phagocytic host cells, including macrophages, dendritic cells, and neutrophils. In this review, we discuss recent progress that has been made in defining the nutrient composition of the Leishmania parasitophorous vacuole, as well as metabolic pathways required by these parasites for virulence. Analysis of the virulence phenotype of Leishmania mutants has been particularly useful in defining carbon sources and nutrient salvage pathways that are essential for parasite persistence and/or induction of pathology. We also review data suggesting that intracellular parasite stages modulate metabolic processes in their host cells in order to generate a more permissive niche.
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Affiliation(s)
- Malcolm J McConville
- Department of Biochemistry and Molecular Biology, University of Melbourne, Bio21 Institute of Molecular Science and Biotechnology, Parkville, Victoria 3010, Australia.
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18
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Fani F, Leprohon P, Légaré D, Ouellette M. Whole genome sequencing of penicillin-resistant Streptococcus pneumoniae reveals mutations in penicillin-binding proteins and in a putative iron permease. Genome Biol 2011; 12:R115. [PMID: 22108223 PMCID: PMC3334601 DOI: 10.1186/gb-2011-12-11-r115] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Revised: 09/29/2011] [Accepted: 11/22/2011] [Indexed: 01/10/2023] Open
Affiliation(s)
- Fereshteh Fani
- Centre de recherche en Infectiologie du Centre de recherche du CHUL and Département de Microbiologie, Infectiologie et Immunologie, Université Laval, Laurier, Québec, Canada
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Abstract
The control of the protozoan parasite Leishmania relies on few drugs with unknown cellular targets and unclear mode of action. Several antileishmanials, however, were shown to induce apoptosis in Leishmania and this death mechanism was further studied in drug-sensitive and drug-resistant Leishmania infantum. In sensitive parasites, antimonials (SbIII), miltefosine (MF) and amphotericin B (AMB), but not paromomycin (PARO), triggered apoptotic cell death associated with reactive oxygen species (ROS). In contrast, Leishmania mutants resistant to SbIII, MF or AMB not only failed to undergo apoptosis following exposure to their respective drugs, but also were more tolerant towards apoptosis induced by other antileishmanials, provided that these killed Leishmania via ROS production. Such tolerance favored the rapid acquisition of multidrug resistance. PARO killed Leishmania in a non-apoptotic manner and failed to produce ROS. PARO resistance neither protected against drug-induced apoptosis nor provided an increased rate of acquisition of resistance to other antileishmanials. However, the PARO-resistant mutant, but not SbIII-, MF- or AMB-resistant mutants, became rapidly cross-resistant to methotrexate, a model drug also not producing ROS. Our results therefore link the mode of killing of drugs to tolerance to cell death and to a facilitated emergence of multidrug resistance. These findings may have fundamental implications in the field of chemotherapeutic interventions.
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20
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Van Assche T, Deschacht M, da Luz RAI, Maes L, Cos P. Leishmania-macrophage interactions: insights into the redox biology. Free Radic Biol Med 2011; 51:337-51. [PMID: 21620959 DOI: 10.1016/j.freeradbiomed.2011.05.011] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 04/24/2011] [Accepted: 05/07/2011] [Indexed: 11/19/2022]
Abstract
Leishmaniasis is a neglected tropical disease that affects about 350 million individuals worldwide. The protozoan parasite has a relatively simple life cycle with two principal stages: the flagellated mobile promastigote living in the gut of the sandfly vector and the intracellular amastigote within phagolysosomal vesicles of the vertebrate host macrophage. This review presents a state-of-the-art overview of the redox biology at the parasite-macrophage interface. Although Leishmania species are susceptible in vitro to exogenous superoxide radical, hydrogen peroxide, nitric oxide, and peroxynitrite, they manage to survive the endogenous oxidative burst during phagocytosis and the subsequent elevated nitric oxide production in the macrophage. The parasite adopts various defense mechanisms to cope with oxidative stress: the lipophosphoglycan membrane decreases superoxide radical production by inhibiting NADPH oxidase assembly and the parasite also protects itself by expressing antioxidant enzymes and proteins. Some of these enzymes could be considered potential drug targets because they are not expressed in mammals. In respect to antileishmanial therapy, the effects of current drugs on parasite-macrophage redox biology and its involvement in the development of drug resistance and treatment failure are presented.
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Affiliation(s)
- Tim Van Assche
- Laboratory of Microbiology Parasitology, and Hygiene, University of Antwerp, B-2020 Antwerp, Belgium
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21
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Sphingolipid degradation by Leishmania major is required for its resistance to acidic pH in the mammalian host. Infect Immun 2011; 79:3377-87. [PMID: 21576322 DOI: 10.1128/iai.00037-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Leishmania parasites alternate between flagellated promastigotes in sand flies and nonflagellated amastigotes in mammals, causing a spectrum of serious diseases. To survive, they must resist the harsh conditions in phagocytes (including acidic pH, elevated temperature, and increased oxidative/nitrosative stress) and evade the immune response. Recent studies have highlighted the importance of sphingolipid (SL) metabolism in Leishmania virulence. In particular, we have generated a Leishmania major iscl(-) mutant which is deficient in SL degradation but grows normally as promastigotes in culture. Importantly, iscl(-) mutants cannot induce pathology in either immunocompetent or immunodeficient mice yet are able to persist at low levels. In this study, we investigated how the degradation of SLs might contribute to Leishmania infection. First, unlike wild-type (WT) L. major, iscl(-) mutants do not trigger polarized T cell responses in mice. Second, like WT parasites, iscl(-) mutants possess the ability to downregulate macrophage activation by suppressing the production of interleukin-12 (IL-12) and nitric oxide. Third, during the stationary phase, iscl(-) promastigotes were extremely vulnerable to acidic pH but not to other adverse conditions, such as elevated temperature and oxidative/nitrosative stress. In addition, inhibition of phagosomal acidification significantly improved iscl(-) survival in murine macrophages. Together, these findings indicate that SL degradation by Leishmania is essential for its adaption to the acidic environment in phagolysosomes but is not required for the suppression of host cell activation. Finally, our studies with iscl(-) mutant-infected mice suggest that having viable, persistent parasites is not sufficient to provide immunity against virulent Leishmania challenge.
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23
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Ong HB, Sienkiewicz N, Wyllie S, Fairlamb AH. Dissecting the metabolic roles of pteridine reductase 1 in Trypanosoma brucei and Leishmania major. J Biol Chem 2011; 286:10429-38. [PMID: 21239486 PMCID: PMC3060496 DOI: 10.1074/jbc.m110.209593] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Leishmania parasites are pteridine auxotrophs that use an NADPH-dependent pteridine reductase 1 (PTR1) and NADH-dependent quinonoid dihydropteridine reductase (QDPR) to salvage and maintain intracellular pools of tetrahydrobiopterin (H4B). However, the African trypanosome lacks a credible candidate QDPR in its genome despite maintaining apparent QDPR activity. Here we provide evidence that the NADH-dependent activity previously reported by others is an assay artifact. Using an HPLC-based enzyme assay, we demonstrate that there is an NADPH-dependent QDPR activity associated with both TbPTR1 and LmPTR1. The kinetic properties of recombinant PTR1s are reported at physiological pH and ionic strength and compared with LmQDPR. Specificity constants (kcat/Km) for LmPTR1 are similar with dihydrobiopterin (H2B) and quinonoid dihydrobiopterin (qH2B) as substrates and about 20-fold lower than LmQDPR with qH2B. In contrast, TbPTR1 shows a 10-fold higher kcat/Km for H2B over qH2B. Analysis of Trypanosoma brucei isolated from infected rats revealed that H4B (430 nm, 98% of total biopterin) was the predominant intracellular pterin, consistent with a dual role in the salvage and regeneration of H4B. Gene knock-out experiments confirmed this: PTR1-nulls could only be obtained from lines overexpressing LmQDPR with H4B as a medium supplement. These cells grew normally with H4B, which spontaneously oxidizes to qH2B, but were unable to survive in the absence of pterin or with either biopterin or H2B in the medium. These findings establish that PTR1 has an essential and dual role in pterin metabolism in African trypanosomes and underline its potential as a drug target.
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Affiliation(s)
- Han B Ong
- Division of Biological Chemistry & Drug Discovery, College of Life Sciences, University of Dundee, Wellcome Trust Biocentre, Dundee DD1 5EH, Scotland, United Kingdom
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24
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Barrack KL, Tulloch LB, Burke LA, Fyfe PK, Hunter WN. Structure of recombinant Leishmania donovani pteridine reductase reveals a disordered active site. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:33-7. [PMID: 21206018 PMCID: PMC3079966 DOI: 10.1107/s174430911004724x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 11/15/2010] [Indexed: 02/04/2023]
Abstract
Pteridine reductase (PTR1) is a potential target for drug development against parasitic Trypanosoma and Leishmania species, protozoa that are responsible for a range of serious diseases found in tropical and subtropical parts of the world. As part of a structure-based approach to inhibitor development, specifically targeting Leishmania species, well ordered crystals of L. donovani PTR1 were sought to support the characterization of complexes formed with inhibitors. An efficient system for recombinant protein production was prepared and the enzyme was purified and crystallized in an orthorhombic form with ammonium sulfate as the precipitant. Diffraction data were measured to 2.5 Å resolution and the structure was solved by molecular replacement. However, a sulfate occupies a phosphate-binding site used by NADPH and occludes cofactor binding. The nicotinamide moiety is a critical component of the active site and without it this part of the structure is disordered. The crystal form obtained under these conditions is therefore unsuitable for the characterization of inhibitor complexes.
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Affiliation(s)
- Keri L. Barrack
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Lindsay B. Tulloch
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Lynsey-Ann Burke
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Paul K. Fyfe
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - William N. Hunter
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
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25
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Jacobs RT, Nare B, Phillips MA. State of the art in African trypanosome drug discovery. Curr Top Med Chem 2011; 11:1255-74. [PMID: 21401507 PMCID: PMC3101707 DOI: 10.2174/156802611795429167] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 11/25/2010] [Indexed: 11/22/2022]
Abstract
African sleeping sickness is endemic in sub-Saharan Africa where the WHO estimates that 60 million people are at risk for the disease. Human African trypanosomiasis (HAT) is 100% fatal if untreated and the current drug therapies have significant limitations due to toxicity and difficult treatment regimes. No new chemical agents have been approved since eflornithine in 1990. The pentamidine analog DB289, which was in late stage clinical trials for the treatment of early stage HAT recently failed due to toxicity issues. A new protocol for the treatment of late-stage T. brucei gambiense that uses combination nifurtomox/eflornithine (NECT) was recently shown to have better safety and efficacy than eflornithine alone, while being easier to administer. This breakthrough represents the only new therapy for HAT since the approval of eflornithine. A number of research programs are on going to exploit the unusual biochemical pathways in the parasite to identify new targets for target based drug discovery programs. HTS efforts are also underway to discover new chemical entities through whole organism screening approaches. A number of inhibitors with anti-trypanosomal activity have been identified by both approaches, but none of the programs are yet at the stage of identifying a preclinical candidate. This dire situation underscores the need for continued effort to identify new chemical agents for the treatment of HAT.
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Affiliation(s)
- Robert T. Jacobs
- SCYNEXIS, Inc., Research Triangle Park, North Carolina 27709-2878
| | - Bakela Nare
- SCYNEXIS, Inc., Research Triangle Park, North Carolina 27709-2878
| | - Margaret A. Phillips
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, Texas 75390-9041
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26
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Dawson A, Tulloch LB, Barrack KL, Hunter WN. High-resolution structures of Trypanosoma brucei pteridine reductase ligand complexes inform on the placement of new molecular entities in the active site of a potential drug target. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2010; 66:1334-40. [PMID: 21123874 PMCID: PMC3655514 DOI: 10.1107/s0907444910040886] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 10/12/2010] [Indexed: 03/07/2023]
Abstract
Pteridine reductase (PTR1) is a potential target for drug development against parasitic Trypanosoma and Leishmania species. These protozoa cause serious diseases for which current therapies are inadequate. High-resolution structures have been determined, using data between 1.6 and 1.1 Å resolution, of T. brucei PTR1 in complex with pemetrexed, trimetrexate, cyromazine and a 2,4-diaminopyrimidine derivative. The structures provide insight into the interactions formed by new molecular entities in the enzyme active site with ligands that represent lead compounds for structure-based inhibitor development and to support early-stage drug discovery.
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Affiliation(s)
- Alice Dawson
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | | | - Keri L. Barrack
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - William N. Hunter
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
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27
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Smirlis D, Duszenko M, Ruiz AJ, Scoulica E, Bastien P, Fasel N, Soteriadou K. Targeting essential pathways in trypanosomatids gives insights into protozoan mechanisms of cell death. Parasit Vectors 2010; 3:107. [PMID: 21083891 PMCID: PMC3136144 DOI: 10.1186/1756-3305-3-107] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 11/17/2010] [Indexed: 11/25/2022] Open
Abstract
Apoptosis is a normal component of the development and health of multicellular organisms. However, apoptosis is now considered a prerogative of unicellular organisms, including the trypanosomatids of the genera Trypanosoma spp. and Leishmania spp., causative agents of some of the most important neglected human diseases. Trypanosomatids show typical hallmarks of apoptosis, although they lack some of the key molecules contributing to this process in metazoans, like caspase genes, Bcl-2 family genes and the TNF-related family of receptors. Despite the lack of these molecules, trypanosomatids appear to have the basic machinery to commit suicide. The components of the apoptotic execution machinery of these parasites are slowly coming into light, by targeting essential processes and pathways with different apoptogenic agents and inhibitors. This review will be confined to the events known to drive trypanosomatid parasites to apoptosis.
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Affiliation(s)
- Despina Smirlis
- Laboratory of Molecular Parasitology, Department of Microbiology, Hellenic Pasteur Institute, 127 Bas, Sofias Ave,, 11521 Athens, Greece.
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28
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Dridi L, Ahmed Ouameur A, Ouellette M. High affinity S-Adenosylmethionine plasma membrane transporter of Leishmania is a member of the folate biopterin transporter (FBT) family. J Biol Chem 2010; 285:19767-75. [PMID: 20406813 PMCID: PMC2888387 DOI: 10.1074/jbc.m110.114520] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 04/12/2010] [Indexed: 11/06/2022] Open
Abstract
S-Adenosylmethionine (AdoMet) is an important methyl group donor that plays a central role in many essential biochemical processes. The parasite Leishmania can both synthesize and transport AdoMet. Leishmania cells resistant to the antifolate methotrexate due to a rearrangement in folate biopterin transporter (FBT) genes were cross-resistant to sinefungin, an AdoMet analogue. FBT gene rearrangements were also observed in Leishmania major cells selected for sinefungin resistance. One of the rearranged FBT genes corresponded to the main AdoMet transporter (AdoMetT1) of Leishmania as determined by gene transfection and gene inactivation experiments. AdoMetT1 was determined to be a high affinity plasma membrane transporter expressed constitutively throughout the growth phases of the parasite. Leishmania cells selected for resistance or naturally insensitive to sinefungin had lower expression of AdoMetT1. A new function in one carbon metabolism, also a pathway of interest for chemotherapeutic interventions, is described for a novel class of membrane proteins found in diverse organisms.
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Affiliation(s)
- Larbi Dridi
- From the Centre de Recherche en Infectiologie du CHUL, Université Laval, Québec City, Québec G1V 4G2, Canada
| | - Amin Ahmed Ouameur
- From the Centre de Recherche en Infectiologie du CHUL, Université Laval, Québec City, Québec G1V 4G2, Canada
| | - Marc Ouellette
- From the Centre de Recherche en Infectiologie du CHUL, Université Laval, Québec City, Québec G1V 4G2, Canada
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29
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Sienkiewicz N, Ong HB, Fairlamb AH. Trypanosoma brucei pteridine reductase 1 is essential for survival in vitro and for virulence in mice. Mol Microbiol 2010; 77:658-71. [PMID: 20545846 PMCID: PMC2916222 DOI: 10.1111/j.1365-2958.2010.07236.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gene knockout and knockdown methods were used to examine essentiality of pteridine reductase (PTR1) in pterin metabolism in the African trypanosome. Attempts to generate PTR1 null mutants in bloodstream form Trypanosoma brucei proved unsuccessful; despite integration of drug selectable markers at the target locus, the gene for PTR1 was either retained at the same locus or elsewhere in the genome. However, RNA interference (RNAi) resulted in complete knockdown of endogenous protein after 48 h, followed by cell death after 4 days. This lethal phenotype was reversed by expression of enzymatically active Leishmania major PTR1 in RNAi lines ((oe)RNAi) or by addition of tetrahydrobiopterin to cultures. Loss of PTR1 was associated with gross morphological changes due to a defect in cytokinesis, resulting in cells with multiple nuclei and kinetoplasts, as well as multiple detached flagella. Electron microscopy also revealed increased numbers of glycosomes, while immunofluorescence microscopy showed increased and more diffuse staining for glycosomal matrix enzymes, indicative of mis-localisation to the cytosol. Mis-localisation was confirmed by digitonin fractionation experiments. RNAi cell lines were markedly less virulent than wild-type parasites in mice and virulence was restored in the (oe)RNAi line. Thus, PTR1 may be a drug target for human African trypanosomiasis.
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Affiliation(s)
- Natasha Sienkiewicz
- Division of Biological Chemistry & Drug Discovery, College of Life Sciences, University of Dundee, Dundee, UK
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Tulloch LB, Martini VP, Iulek J, Huggan JK, Lee JH, Gibson CL, Smith TK, Suckling CJ, Hunter WN. Structure-based design of pteridine reductase inhibitors targeting African sleeping sickness and the leishmaniases. J Med Chem 2010; 53:221-9. [PMID: 19916554 PMCID: PMC2804273 DOI: 10.1021/jm901059x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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Pteridine reductase (PTR1) is a target for drug development against Trypanosoma and Leishmania species, parasites that cause serious tropical diseases and for which therapies are inadequate. We adopted a structure-based approach to the design of novel PTR1 inhibitors based on three molecular scaffolds. A series of compounds, most newly synthesized, were identified as inhibitors with PTR1-species specific properties explained by structural differences between the T. brucei and L. major enzymes. The most potent inhibitors target T. brucei PTR1, and two compounds displayed antiparasite activity against the bloodstream form of the parasite. PTR1 contributes to antifolate drug resistance by providing a molecular bypass of dihydrofolate reductase (DHFR) inhibition. Therefore, combining PTR1 and DHFR inhibitors might improve therapeutic efficacy. We tested two new compounds with known DHFR inhibitors. A synergistic effect was observed for one particular combination highlighting the potential of such an approach for treatment of African sleeping sickness.
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Affiliation(s)
- Lindsay B Tulloch
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD15EH, UK
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Mukherjee A, Roy G, Guimond C, Ouellette M. The γ-glutamylcysteine synthetase gene of Leishmania is essential and involved in response to oxidants. Mol Microbiol 2009; 74:914-27. [DOI: 10.1111/j.1365-2958.2009.06907.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Nare B, Garraway LA, Vickers TJ, Beverley SM. PTR1-dependent synthesis of tetrahydrobiopterin contributes to oxidant susceptibility in the trypanosomatid protozoan parasite Leishmania major. Curr Genet 2009; 55:287-99. [PMID: 19396443 PMCID: PMC2759280 DOI: 10.1007/s00294-009-0244-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2009] [Revised: 04/04/2009] [Accepted: 04/07/2009] [Indexed: 10/20/2022]
Abstract
Leishmania must survive oxidative stress, but lack many classical antioxidant enzymes and rely heavily on trypanothione-dependent pathways. We used forward genetic screens to recover loci mediating oxidant resistance via overexpression in Leishmania major, which identified pteridine reductase 1 (PTR1). Comparisons of isogenic lines showed ptr1 (-) null mutants were 18-fold more sensitive to H(2)O(2) than PTR1-overproducing lines, and significant three- to fivefold differences were seen with a broad panel of oxidant-inducing agents. The toxicities of simple nitric oxide generators and other drug classes (except antifolates) were unaffected by PTR1 levels. H(2)O(2) susceptibility could be modulated by exogenous biopterin but not folate, in a PTR1- but not dihydrofolate reductase-dependent manner, implicating H(4)B metabolism specifically. Neither H(2)O(2) consumption nor the level of intracellular oxidative stress was affected by PTR1 levels. Coupled with the fact that reduced pteridines are at least 100-fold less abundant than cellular thiols, these data argue strongly that reduced pteridines act through a mechanism other than scavenging. The ability of unconjugated pteridines to counter oxidative stress has implications to infectivity and response to chemotherapy. Since the intracellular pteridine levels of Leishmania can be readily manipulated, these organisms offer a powerful setting for the dissection of pteridine-dependent oxidant susceptibility in higher eukaryotes.
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Affiliation(s)
- Bakela Nare
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115
| | - Levi A. Garraway
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115
| | - Tim J. Vickers
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis MO 63110
| | - Stephen M. Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis MO 63110
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115
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