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Kour P, Saha P, Sharma DK, Singh K. DNA topoisomerases as a drug target in Leishmaniasis: Structural and mechanistic insights. Int J Biol Macromol 2024; 256:128401. [PMID: 38007027 DOI: 10.1016/j.ijbiomac.2023.128401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 11/09/2023] [Accepted: 11/22/2023] [Indexed: 11/27/2023]
Abstract
Leishmaniasis, caused by a protozoan parasite, is among humanity's costliest banes, owing to the high mortality and morbidity ratio in poverty-stricken areas. To date, no vaccine is available for the complete cure of the disease. Current chemotherapy is expensive, has undesirable side effects, and faces drug resistance limitations and toxicity concerns. The substantial differences in homology between leishmanial DNA topoisomerase IB compared with the human counterparts provided a new lead in the study of the structural determinants that can be targeted. Several research groups explored this molecular target, trying to fill the therapeutic gap, and came forward with various anti-leishmanial scaffolds. This article is a comprehensive review of knowledge about topoisomerases as an anti-leishmanial drug target and their inhibitors collected over the years. In addition to information on molecular targets and reported scaffolds, the review details the structure-activity relationship of described compounds with leishmanial Topoisomerase IB. Moreover, the work also includes information about the structure of the inhibitors, showing common interacting residues with leishmanial topoisomerases that drive their mode of action towards them. Finally, in search of topoisomerase inhibitors at the stage of clinical trials, we have listed all the drugs that have been in clinical trials against leishmaniasis.
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Affiliation(s)
- Parampreet Kour
- Infectious Diseases Division, CSIR- Indian Institute of Integrative Medicine, Jammu 180001, India
| | - Pallavi Saha
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology Banaras Hindu University, Varanasi 221005, India
| | - Deepak K Sharma
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology Banaras Hindu University, Varanasi 221005, India
| | - Kuljit Singh
- Infectious Diseases Division, CSIR- Indian Institute of Integrative Medicine, Jammu 180001, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
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2
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Reguera RM, Elmahallawy EK, García-Estrada C, Carbajo-Andrés R, Balaña-Fouce R. DNA Topoisomerases of Leishmania Parasites; Druggable Targets for Drug Discovery. Curr Med Chem 2019; 26:5900-5923. [DOI: 10.2174/0929867325666180518074959] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 03/15/2018] [Accepted: 05/14/2018] [Indexed: 12/13/2022]
Abstract
DNA topoisomerases (Top) are a group of isomerase enzymes responsible for controlling the topological problems caused by DNA double helix in the cell during the processes of replication, transcription and recombination. Interestingly, these enzymes have been known since long to be key molecular machines in several cellular processes through overwinding or underwinding of DNA in all living organisms. Leishmania, a trypanosomatid parasite responsible for causing fatal diseases mostly in impoverished populations of low-income countries, has a set of six classes of Top enzymes. These are placed in the nucleus and the single mitochondrion and can be deadly targets of suitable drugs. Given the fact that there are clear differences in structure and expression between parasite and host enzymes, numerous studies have reported the therapeutic potential of Top inhibitors as antileishmanial drugs. In this regard, numerous compounds have been described as Top type IB and Top type II inhibitors in Leishmania parasites, such as camptothecin derivatives, indenoisoquinolines, indeno-1,5- naphthyridines, fluoroquinolones, anthracyclines and podophyllotoxins. The aim of this review is to highlight several facts about Top and Top inhibitors as potential antileishmanial drugs, which may represent a promising strategy for the control of this disease of public health importance.
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Affiliation(s)
- Rosa M. Reguera
- Department of Biomedical Sciences, University of Leon (ULE), Leon, Spain
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3
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Chowdhury SR, Majumder HK. DNA Topoisomerases in Unicellular Pathogens: Structure, Function, and Druggability. Trends Biochem Sci 2019; 44:415-432. [PMID: 30609953 DOI: 10.1016/j.tibs.2018.12.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/20/2018] [Accepted: 12/03/2018] [Indexed: 02/06/2023]
Abstract
All organisms, including unicellular pathogens, compulsorily possess DNA topoisomerases for successful nucleic acid metabolism. But particular subtypes of topoisomerases exist, in all prokaryotes and in some unicellular eukaryotes, that are absent in higher eukaryotes. Moreover, topoisomerases from pathogenic members of a niche possess some unique molecular architecture and functionalities completely distinct from their nonpathogenic colleagues. This review will highlight the unique attributes associated with the structures and functions of topoisomerases from the unicellular pathogens, with special reference to bacteria and protozoan parasites. It will also summarise the progress made in the domain pertaining to the druggability of these topoisomerases, upon which a future platform for therapeutic development can be successfully constructed.
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Affiliation(s)
- Somenath Roy Chowdhury
- Laboratory of Molecular Parasitology, Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700 032, India
| | - Hemanta K Majumder
- Laboratory of Molecular Parasitology, Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700 032, India.
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Velásquez AMA, Ribeiro WC, Venn V, Castelli S, Camargo MSD, de Assis RP, de Souza RA, Ribeiro AR, Passalacqua TG, da Rosa JA, Baviera AM, Mauro AE, Desideri A, Almeida-Amaral EE, Graminha MAS. Efficacy of a Binuclear Cyclopalladated Compound Therapy for Cutaneous Leishmaniasis in the Murine Model of Infection with Leishmania amazonensis and Its Inhibitory Effect on Topoisomerase 1B. Antimicrob Agents Chemother 2017; 61:e00688-17. [PMID: 28507113 PMCID: PMC5527659 DOI: 10.1128/aac.00688-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 05/02/2017] [Indexed: 12/29/2022] Open
Abstract
Leishmaniasis is a disease found throughout the (sub)tropical parts of the world caused by protozoan parasites of the Leishmania genus. Despite the numerous problems associated with existing treatments, pharmaceutical companies continue to neglect the development of better ones. The high toxicity of current drugs combined with emerging resistance makes the discovery of new therapeutic alternatives urgent. We report here the evaluation of a binuclear cyclopalladated complex containing Pd(II) and N,N'-dimethylbenzylamine (Hdmba) against Leishmania amazonensis The compound [Pd(dmba)(μ-N3)]2 (CP2) inhibits promastigote growth (50% inhibitory concentration [IC50] = 13.2 ± 0.7 μM) and decreases the proliferation of intracellular amastigotes in in vitro incubated macrophages (IC50 = 10.2 ± 2.2 μM) without a cytotoxic effect when tested against peritoneal macrophages (50% cytotoxic concentration = 506.0 ± 10.7 μM). In addition, CP2 was also active against T. cruzi intracellular amastigotes (IC50 = 2.3 ± 0.5 μM, selective index = 225), an indication of its potential for use in Chagas disease therapy. In vivo assays using L. amazonensis-infected BALB/c showed an 80% reduction in parasite load compared to infected and nontreated animals. Also, compared to amphotericin B treatment, CP2 did not show any side effects, which was corroborated by the analysis of plasma levels of different hepatic and renal biomarkers. Furthermore, CP2 was able to inhibit Leishmania donovani topoisomerase 1B (Ldtopo1B), a potentially important target in this parasite. (This study has been registered at ClinicalTrials.gov under identifier NCT02169141.).
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Affiliation(s)
- Angela Maria Arenas Velásquez
- São Paulo State University (UNESP), School of Pharmaceutical Sciences, Araraquara, Brazil
- São Paulo State University (UNESP), Institute of Chemistry, Araraquara, Brazil
| | - Willian Campos Ribeiro
- São Paulo State University (UNESP), School of Pharmaceutical Sciences, Araraquara, Brazil
| | - Vutey Venn
- University of Rome, Tor Vergata, Rome, Italy
| | | | | | - Renata Pires de Assis
- São Paulo State University (UNESP), School of Pharmaceutical Sciences, Araraquara, Brazil
| | | | | | - Thaís Gaban Passalacqua
- São Paulo State University (UNESP), School of Pharmaceutical Sciences, Araraquara, Brazil
- São Paulo State University (UNESP), Institute of Chemistry, Araraquara, Brazil
| | - João Aristeu da Rosa
- São Paulo State University (UNESP), School of Pharmaceutical Sciences, Araraquara, Brazil
| | - Amanda Martins Baviera
- São Paulo State University (UNESP), School of Pharmaceutical Sciences, Araraquara, Brazil
| | | | | | | | - Marcia A S Graminha
- São Paulo State University (UNESP), School of Pharmaceutical Sciences, Araraquara, Brazil
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Affiliation(s)
- Giovanni Capranico
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
8/2, 40126 Bologna, Italy
| | - Jessica Marinello
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
8/2, 40126 Bologna, Italy
| | - Giovanni Chillemi
- SCAI
SuperComputing Applications and Innovation Department, Cineca, Via dei Tizii 6, 00185 Rome, Italy
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Effect of topoisomerase inhibitors and DNA-binding drugs on the cell proliferation and ultrastructure of Trypanosoma cruzi. Int J Antimicrob Agents 2011; 37:449-56. [DOI: 10.1016/j.ijantimicag.2010.11.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 10/31/2010] [Accepted: 11/01/2010] [Indexed: 11/22/2022]
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Sengupta S, Ganguly A, Roy A, Bosedasgupta S, D'Annessa I, Desideri A, Majumder HK. ATP independent type IB topoisomerase of Leishmania donovani is stimulated by ATP: an insight into the functional mechanism. Nucleic Acids Res 2010; 39:3295-309. [PMID: 21186185 PMCID: PMC3082896 DOI: 10.1093/nar/gkq1284] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Most type IB topoisomerases do not require ATP and Mg(2+) for activity. However, as shown previously for vaccinia topoisomerase I, we demonstrate that ATP stimulates the relaxation activity of the unusual heterodimeric type IB topoisomerase from Leishmania donovani (LdTOP1L/S) in the absence of Mg(2+). The stimulation is independent of ATP hydrolysis but requires salt as a co-activator. ATP binds to LdTOP1L/S and increases its rate of strand rotation. Docking studies indicate that the amino acid residues His93, Tyr95, Arg188 and Arg190 of the large subunit may be involved in ATP binding. Site directed mutagenesis of these four residues individually to alanine and subsequent relaxation assays reveal that the R190A mutant topoisomerase is unable to exhibit ATP-mediated stimulation in the absence of Mg(2+). However, the ATP-independent relaxation activities of all the four mutant enzymes remain unaffected. Additionally, we provide evidence that ATP binds LdTOP1L/S and modulates the activity of the otherwise ATP-independent enzyme. This study establishes ATP as an activator of LdTOP1L/S in the absence of Mg(2+).
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Affiliation(s)
- Souvik Sengupta
- Molecular Parasitology Laboratory, Indian Institute of Chemical Biology, 4 Raja S C Mullick Road, Kolkata 700032, India
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García-Estrada C, Prada CF, Fernández-Rubio C, Rojo-Vázquez F, Balaña-Fouce R. DNA topoisomerases in apicomplexan parasites: promising targets for drug discovery. Proc Biol Sci 2010; 277:1777-87. [PMID: 20200034 DOI: 10.1098/rspb.2009.2176] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The phylum Apicomplexa includes a large group of protozoan parasites responsible for a wide range of animal and human diseases. Destructive pathogens, such as Plasmodium falciparum and Plasmodium vivax, causative agents of human malaria, Cryptosporidium parvum, responsible of childhood diarrhoea, and Toxoplasma gondii, responsible for miscarriages and abortions in humans, are frequently associated with HIV immunosuppression in AIDS patients. The lack of effective vaccines, along with years of increasing pressure to eradicate outbreaks with the use of drugs, has favoured the formation of multi-drug resistant strains in endemic areas. Almost all apicomplexan of medical interest contain two endosymbiotic organelles that contain their own mitochondrial and apicoplast DNA. Apicoplast is an attractive target for drug testing because in addition to harbouring singular metabolic pathways absent in the host, it also has its own transcription and translation machinery of bacterial origin. Accordingly, apicomplexan protozoa contain an interesting mixture of enzymes to unwind DNA from eukaryotic and prokaryotic origins. On the one hand, the main mechanism of DNA unwinding includes the scission of one-type I-or both DNA strands-type II eukaryotic topoisomerases, establishing transient covalent bonds with the scissile end. These enzymes are targeted by camptothecin and etoposide, respectively, two natural drugs whose semisynthetic derivatives are currently used in cancer chemotherapy. On the other hand, DNA gyrase is a bacterial-borne type II DNA topoisomerase that operates within the apicoplast and is effectively targeted by bacterial antibiotics like fluoroquinolones and aminocoumarins. The present review is an update on the new findings concerning topoisomerases in apicomplexan parasites and the role of these enzymes as targets for therapeutic agents.
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Affiliation(s)
- Carlos García-Estrada
- Departamento de Ciencias Biomédicas (INTOXCAL), Universidad de León, , Campus de Vegazana s/n, León, Spain
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Mutational studies reveal lysine 352 on the large subunit is indispensable for catalytic activity of bi-subunit topoisomerase I from Leishmania donovani. Mol Biochem Parasitol 2009; 165:57-66. [PMID: 19393162 DOI: 10.1016/j.molbiopara.2009.01.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 12/31/2008] [Accepted: 01/08/2009] [Indexed: 11/22/2022]
Abstract
From the vanadate complex crystal structure of Leishmania donovani topoisomerase I, several amino acid residues have been implicated to be involved in the catalytic reaction. Although several predictions and propositions have been made, the exact role of these amino acids has not yet been clearly demonstrated in vitro. Among these residues, lysine 352 and arginine 314 stand as potential candidates for playing the role of a general acid during the cleavage step. In this study, we have characterized the role of lysine 352 on the large subunit, by site-directed mutagenesis and have tried to identify the general acid that can protonate the 5?-O atom of the leaving strand. Studies with the mutant enzymes reveal that, relaxation activity was severely affected when Lys352 was mutated to arginine or alanine (K352R or K352A). Mutation of Arg314 to Lys (R314K) has very little effect on the relaxation activity. Detailed study reveals that, both cleavage and religation steps are severely affected in case of K352R and K352A and the cleavage religation equilibrium is shifted towards the cleavage. On the contrary, the R314K mutant exhibits only a slightly slower rate of cleavage compared to wild-type enzyme. Cleavage assays with an oligonucleotide containing 5?-bridging phosphorothiolate indicate that Lys352 acts as a general acid in the cleavage step. Altogether, this study establishes the indispensable role of lysine 352 in the catalytic reaction of L. donovani topoisomerase I.
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Das BB, Ganguly A, Majumder HK. DNA Topoisomerases of Leishmania: The Potential Targets for Anti-Leishmanial Therapy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 625:103-15. [DOI: 10.1007/978-0-387-77570-8_9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Díaz González R, Pérez Pertejo Y, Ordóñez D, Balaña-Fouce R, Reguera RM. Deletion study of DNA topoisomerase IB from Leishmania donovani: searching for a minimal functional heterodimer. PLoS One 2007; 2:e1177. [PMID: 18000548 PMCID: PMC2063514 DOI: 10.1371/journal.pone.0001177] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Accepted: 10/26/2007] [Indexed: 11/25/2022] Open
Abstract
The substantial differences between trypanosomal and leishmanial DNA topoisomerase IB concerning to their homologues in mammals have provided a new lead in the study of the structural determinants that can be effectively targeted. Leishmania donovani, the causative agent of visceral leishmaniasis, contains an unusual heterodimeric DNA topoisomerase IB. The catalytically active enzyme consists of a large subunit (LdTopIL), which contains the non-conserved N-terminal end and the phylogenetically conserved “core” domain, and of a small subunit (LdTopIS) which harbors the C-terminal region with the characteristic tyrosine residue in the active site. Heterologous co-expression of LdTopIL and LdTopIS genes in a topoisomerase I deficient yeast strain, reconstitutes a fully functional enzyme LdTopIL/S which can be used for structural studies. An approach by combinatorial cloning of deleted genes encoding for truncated versions of both subunits was used in order to find out structural insights involved in enzyme activity or protein-protein interaction. The role played by the non-conserved N-terminal extension of LdTopIL in both relaxation activity and CPT sensitivity has been examined co-expressing the full-length LdTopIS and a fully active LdTopIΔS deletion with several deletions of LdTopIL lacking growing sequences of the N-terminal end. The sequential deletion study shows that the first 26 amino acids placed at the N-terminal end and a variable region comprised between Ala548 to end of the C-terminal extension of LdTopIL were enzymatically dispensable. Altogether this combinatorial approach provides important structural insights of the regions involved in relaxation activity and for understanding the atypical structure of this heterodimeric enzyme.
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Affiliation(s)
- Rosario Díaz González
- Departamento de Farmacología y Toxicología (INTOXCAL), Universidad de León, León, Spain
| | - Yolanda Pérez Pertejo
- Departamento de Farmacología y Toxicología (INTOXCAL), Universidad de León, León, Spain
| | - David Ordóñez
- Departamento de Farmacología y Toxicología (INTOXCAL), Universidad de León, León, Spain
| | - Rafael Balaña-Fouce
- Departamento de Farmacología y Toxicología (INTOXCAL), Universidad de León, León, Spain
- * To whom correspondence should be addressed. E-mail:
| | - Rosa M. Reguera
- Departamento de Farmacología y Toxicología (INTOXCAL), Universidad de León, León, Spain
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Ganguly A, Das BB, Sen N, Roy A, Dasgupta SB, Majumder HK. 'LeishMan' topoisomerase I: an ideal chimera for unraveling the role of the small subunit of unusual bi-subunit topoisomerase I from Leishmania donovani. Nucleic Acids Res 2006; 34:6286-97. [PMID: 17098934 PMCID: PMC1669778 DOI: 10.1093/nar/gkl829] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The active site tyrosine residue of all monomeric type IB topoisomerases resides in the C-terminal domain of the enzyme. Leishmania donovani, possesses unusual heterodimeric type IB topoisomerase. The small subunit harbors the catalytic tyrosine within the SKXXY motif. To explore the functional relationship between the two subunits, we have replaced the small subunit of L.donovani topoisomerase I with a C-terminal fragment of human topoisomerase I (HTOP14). The purified LdTOP1L (large subunit of L.donovani topoisomerase I) and HTOP14 were able to reconstitute topoisomerase I activity when mixed in vitro. This unusual enzyme, 'LeishMan' topoisomerase I (Leish for Leishmania and Man for human) exhibits less efficiency in DNA binding and strand passage compared with LdTOP1L/S. Fusion of LdTOP1L with HTOP14 yielded a more efficient enzyme with greater affinity for DNA and faster strand passage ability. Both the chimeric enzymes are less sensitive to camptothecin than LdTOP1L/S. Restoration of topoisomerase I activity by LdTOP1L and HTOP14 suggests that the small subunit of L.donovani topoisomerase I is primarily required for supplying the catalytic tyrosine. Moreover, changes in the enzyme properties due to substitution of LdTOP1S with HTOP14 indicate that the small subunit contributes to subunit interaction and catalytic efficiency of the enzyme.
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Affiliation(s)
| | | | | | | | | | - Hemanta K. Majumder
- To whom correspondence should be addressed. Tel: +91 33 2412 3207; Fax: +91 33 2473 5197;
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Das BB, Sengupta T, Ganguly A, Majumder HK. Topoisomerases of kinetoplastid parasites: why so fascinating? Mol Microbiol 2006; 62:917-27. [PMID: 17042788 DOI: 10.1111/j.1365-2958.2006.05428.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DNA topoisomerases are the key enzymes involved in carrying out high precision DNA transactions inside the cells. However, they are detrimental to the cell when a wide variety of topoisomerase-targeted drugs generate cytotoxic lesions by trapping the enzymes in covalent complexes on the DNA. The discovery of unusual heterodimeric topoisomerase I in kinetoplastid family added a new twist in topoisomerase research related to evolution, functional conservation and their preferential sensitivity to Camptothecin. On the other hand, structural and mechanistic studies on kinetoplastid topoisomerase II delineate some distinguishing features that differentiate the parasitic enzyme from its prokaryotic and eukaryotic counterparts. This review summarizes the recent advances in research in kinetoplastid topoisomerases, their evolutionary significance and the death of the unicellular parasite Leishmania donovani induced by topoisomerase I inhibitor camptothecin.
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Affiliation(s)
- Benu Brata Das
- Department of Molecular Parasitology, Indian Institute of Chemical Biology, Kolkata 700032, India
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14
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Balaña-Fouce R, Redondo CM, Pérez-Pertejo Y, Díaz-González R, Reguera RM. Targeting atypical trypanosomatid DNA topoisomerase I. Drug Discov Today 2006; 11:733-40. [PMID: 16846801 DOI: 10.1016/j.drudis.2006.06.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Revised: 04/21/2006] [Accepted: 06/16/2006] [Indexed: 11/26/2022]
Abstract
Tropical diseases produced by kinetoplastid protozoa are among humanity's costliest banes, owing to high mortality and the economic burden resulting from morbidity. Drug resistant strains of parasites, together with insecticide-resistant vectors, are contributing to their increased prevalence in the developing world. Their extension now threatens industrialized countries because of opportunistic infections in immuno-compromised individuals. Current chemotherapy is expensive, has undesirable side effects and, in many patients, is only marginally effective. Based on the clinical success of camptothecin derivatives as anticancer agents, DNA topoisomerases have been identified as targets for drug development. The substantial differences in homology between trypanosome and leishmania DNA topoisomerase IB compared with the human form provides a new lead in the study of the structural determinants that can be targeted.
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Affiliation(s)
- Rafael Balaña-Fouce
- Department of Pharmacology and Toxicology, University of León, Campus de Vegazana s/n 24071 León, Spain.
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15
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Reguera RM, Redondo CM, Gutierrez de Prado R, Pérez-Pertejo Y, Balaña-Fouce R. DNA topoisomerase I from parasitic protozoa: A potential target for chemotherapy. ACTA ACUST UNITED AC 2006; 1759:117-31. [PMID: 16757380 DOI: 10.1016/j.bbaexp.2006.03.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Revised: 03/22/2006] [Accepted: 03/30/2006] [Indexed: 11/28/2022]
Abstract
The growing occurrence of drug resistant strains of unicellular prokaryotic parasites, along with insecticide-resistant vectors, are the factors contributing to the increased prevalence of tropical diseases in underdeveloped and developing countries, where they are endemic. Malaria, cryptosporidiosis, African and American trypanosomiasis and leishmaniasis threaten human beings, both for the high mortality rates involved and the economic loss resulting from morbidity. Due to the fact that effective immunoprophylaxis is not available at present; preventive sanitary measures and pharmacological approaches are the only sources to control the undesirable effects of such diseases. Current anti-parasitic chemotherapy is expensive, has undesirable side effects or, in many patients, is only marginally effective. Under this point of view molecular biology techniques and drug discovery must walk together in order to find new targets for chemotherapy intervention. The identification of DNA topoisomerases as a promising drug target is based on the clinical success of camptothecin derivatives as anticancer agents. The recent detection of substantial differences between trypanosome and leishmania DNA topoisomerase IB with respect to their homologues in mammals has provided a new lead in the study of the structural determinants that can be effectively targeted. The present report is an up to date review of the new findings on type IB DNA topoisomerase in unicellular parasites and the role of these enzymes as targets for therapeutic agents.
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Affiliation(s)
- R M Reguera
- Dpto. Farmacología y Toxicología (INTOXCAL), Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
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Davies DR, Mushtaq A, Interthal H, Champoux JJ, Hol WGJ. The structure of the transition state of the heterodimeric topoisomerase I of Leishmania donovani as a vanadate complex with nicked DNA. J Mol Biol 2006; 357:1202-10. [PMID: 16487540 DOI: 10.1016/j.jmb.2006.01.022] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Revised: 12/29/2005] [Accepted: 01/03/2006] [Indexed: 10/25/2022]
Abstract
Type IB topoisomerases are essential enzymes that are responsible for relaxing superhelical tension in DNA by forming a transient covalent nick in one strand of the DNA duplex. Topoisomerase I is a target for anti-cancer drugs such as camptothecin, and these drugs also target the topoisomerases I in pathogenic trypanosomes including Leishmania species and Trypanosoma brucei. Most eukaryotic enzymes, including human topoisomerase I, are monomeric. However, for Leishmania donovani, the DNA-binding activity and the majority of residues involved in catalysis are located in a large subunit, designated TOP1L, whereas the catalytic tyrosine residue responsible for covalent attachment to DNA is located in a smaller subunit, called TOP1S. Here, we present the 2.27A crystal structure of an active truncated L.donovani TOP1L/TOP1S heterodimer bound to nicked double-stranded DNA captured as a vanadate complex. The vanadate forms covalent linkages between the catalytic tyrosine residue of the small subunit and the nicked ends of the scissile DNA strand, mimicking the previously unseen transition state of the topoisomerase I catalytic cycle. This structure fills a critical gap in the existing ensemble of topoisomerase I structures and provides crucial insights into the catalytic mechanism.
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Affiliation(s)
- Douglas R Davies
- Department of Biochemistry, Box 357742, University of Washington, Seattle, WA 98195-7742, USA
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Marquis JF, Hardy I, Olivier M. Topoisomerase I amino acid substitutions, Gly185Arg and Asp325Glu, confer camptothecin resistance in Leishmania donovani. Antimicrob Agents Chemother 2005; 49:1441-6. [PMID: 15793124 PMCID: PMC1068627 DOI: 10.1128/aac.49.4.1441-1446.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antitumor compound camptothecin (CPT) is also recognized for its specific activity against Leishmania donovani topoisomerase I (Topo-I). In consequence, defining CPT resistance mechanisms represents an important strategic tool in the acquisition of a better understanding of its mode of action. In the present study, we selected a single highly resistant L. donovani strain termed LdRCPT.160 by stepwise exposure to CPT. Gene sequencing revealed two single nucleotide mutations in the LdRCPT.160 LdTOP1A gene, resulting in two amino acid substitutions (Gly185Arg and Asp325Glu) in the protein. Moreover, these two substitutions observed in the LdTOP1A protein were correlated with a decreased Topo-I DNA relaxation activity in these resistant parasites. Nevertheless, there was no change in the LdTOP1A gene expression level. Interestingly, transfection studies of the LdRCPT.160 LdTOP1A gene in its wild-type counterpart showed that it induced CPT resistance. Site-directed mutagenesis studies demonstrated that, despite a substantial level of resistance conferred by the Gly185Arg and Asp325Glu substitutions separately, both were essential to reach a high-resistance phenotype. Of interest, the amino acid substitutions observed in LdRCPT.160 LdTOP1A protein occurred near the amino acids previously predicted to interact with CPT, providing new insight into the mechanism of CPT molecular action.
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Affiliation(s)
- Jean-François Marquis
- Centre for the Study of Host Resistance and the Research Institute of McGill University Health Centre, Department of Experimental Medicine, McGill University, Lyman Duff Building, 3775 University St., Room 600, Montréal, Québec, Canada H3A 2B4
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18
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Marquis JF, Hardy I, Olivier M. Resistance mechanism development to the topoisomerase-I inhibitor Hoechst 33342 byLeishmania donovani. Parasitology 2005; 131:197-206. [PMID: 16145936 DOI: 10.1017/s0031182005007328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The bisbenzimidazole compound Hoechst 33342 (Ho342) has been identified as a specific Topoisomerase-I (Topo-I) inhibitor in mammalian cells. More recently, we have reported the ability of Ho342 to targetL. donovaniTopo-I, leading to parasite growth inhibitionin vitroby mechanisms involving DNA breakage and apoptosis-like phenomenon. As the Ho342 lead molecule (2,5′-Bi-1H-benzimidazole) can be used as a starting structure for derivative compounds more effective againstLeishmania, defining the Ho342 resistance mechanism(s) inLeishmaniarepresents an important strategic tool. In the present study, we selected resistant parasites to Ho342 (LdRHo.300). While we observed an increase of the Topo-I gene expression correlated by a higher Topo-I DNA relaxation activity, the Topo-I genes (LdTOP1AandLdTOP1B) sequencing did not reveal any mutation for the resistant parasites. Moreover, our results on Ho342 cellular accumulation suggested the presence of a potential energy-dependent Ho342 transporter in the wild-type parasite, and that an alteration of this transporter has occurred inLdRHo.300, leading to an altered drug accumulation. Collectively, Ho342 resistance characterization provided results supporting that the resistance developed byLdRHo.300involves complex mechanisms, most likely dominated by an altered drug accumulation, providing new insight in the Ho342 resistance mechanisms.
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Affiliation(s)
- J F Marquis
- Centre for the Study of Host Resistance and the Research Institute of McGill University Health Centre, Department of Experimental Medicine, McGill University, Montreal, Quebec, Canada
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19
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Walker J, Saravia NG. INHIBITION OF LEISHMANIA DONOVANI PROMASTIGOTE DNA TOPOISOMERASE I AND HUMAN MONOCYTE DNA TOPOISOMERASES I AND II BY ANTIMONIAL DRUGS AND CLASSICAL ANTITOPOISOMERASE AGENTS. J Parasitol 2004; 90:1155-62. [PMID: 15562618 DOI: 10.1645/ge-3347] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We have compared the inhibitor sensitivities of DNA topoisomerase I (TOPI) from Leishmania donovani promastigotes and TOPs I and II of human monocytes using pentavalent and trivalent antimonials (SbV, SbIII) and classical TOP inhibitors. Bis-benzimidazoles (Hoechst-33258 and -33342) were potent inhibitors of both parasite and human TOPI, but Hoechst-33342 was markedly less cytotoxic to promastigotes than to monocytes in vitro. Leishmania donovani was also considerably less sensitive than monocytes to camptothecin, both at enzyme and cellular levels. Sodium stibogluconate (SSG) was the only antimonial to inhibit TOPI, exhibiting a significant (P < 0.05) 3-fold greater potency against the L. donovani enzyme but showed low cytotoxicities against intact promastigotes. The SbV meglumine antimoniate failed to inhibit TOPI and showed negligible cytotoxicities, whereas SbIII drugs were lethal to parasites and monocytes yet poor inhibitors of TOPI. Monocyte TOPII was inhibited by bis-benzimidazoles and insensitive to antimonials and camptothecin. The disparity between the high leishmanicidal activity and low anti-TOPI potency of SbIII indicates that in vivo targeting of L. donovani TOPI by the reductive pathway of antimonial activation is improbable. Nevertheless, the potent direct inhibition of TOPI by SSG and the differential interactions of camptothecin with L. donovani and human TOPI support the possibility of developing parasite-specific derivatives.
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Affiliation(s)
- John Walker
- Centro Internacional de Entrenamiento e Investigaciones Medicas Avenida 1 Norte No. 3-03, AA 5390, Cali, Colombia.
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20
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Das A, Dasgupta A, Sengupta T, Majumder HK. Topoisomerases of kinetoplastid parasites as potential chemotherapeutic targets. Trends Parasitol 2004; 20:381-7. [PMID: 15246322 DOI: 10.1016/j.pt.2004.06.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The protozoan parasites Trypanosoma, Leishmania and Crithidia, which belong to the order kinetoplastidae, emerge from the most ancient eukaryotic lineages. The diversity found in the life cycle of these organisms must be directed by genetic events, wherein topoisomerases play an important role in cellular processes affecting the topology and organization of intracellular DNA. Topoisomerases are valuable as potential drug targets because they have indispensable function in cell biology. This review summarizes what is known about topoisomerase genes and proteins of kinetoplastid parasites and the roles of these enzymes as targets for therapeutic agents.
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Affiliation(s)
- Aditi Das
- Sealy Center for Molecular Sciences, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
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21
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Das BB, Sen N, Ganguly A, Majumder HK. Reconstitution and functional characterization of the unusual bi-subunit type I DNA topoisomerase from Leishmania donovani. FEBS Lett 2004; 565:81-8. [PMID: 15135057 DOI: 10.1016/j.febslet.2004.03.078] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2004] [Revised: 03/18/2004] [Accepted: 03/18/2004] [Indexed: 11/26/2022]
Abstract
Leishmania donovani topoisomerase I is an unusual bi-subunit enzyme. The activity of the enzyme has been detected when the genes of the individual subunits were co-expressed in yeast [J. Biol. Chem. 278 (2003) 3521]. Here, we report for the first time, the in vitro reconstitution of the two recombinant proteins, LdTOP1L and LdTOP1S, corresponding to the large and small subunits and localization of the active enzyme in both the nucleus and kinetoplast. The proteins were purified from bacterial extract and the activity was measured by plasmid DNA relaxation assay. LdTOP1L and LdTOP1S form a direct 1:1 heterodimer complex through protein-protein interaction. Under standard relaxation assay condition (50 mM KCl and 10 mM Mg(2+)), reconstituted enzyme (LdTOP1LS) showed reduced processivity as well as 2-fold reduced affinity for DNA compared to eukaryotic monomeric rat liver topoisomerase I (RLTOP1). Cleavage assay at various salt concentrations reveals that Camptothecin (CPT) enhanced the formation of "cleavable complex" at low salt. Interaction between the two subunits leading to the formation of an active complex could be explored as an insight for development of new therapeutic agents with specific selectivity.
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Affiliation(s)
- Benu Brata Das
- Department of Molecular Parasitology, Indian Institute of Chemical Biology 4, Raja S.C. Mullick Road, Kolkata 700032, India
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22
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Marquis JF, Makhey D, LaVoie EJ, Olivier M. EFFECTS OF TOPOISOMERASES INHIBITORS PROTOBERBERINE ON LEISHMANIA DONOVANI GROWTH, MACROPHAGE FUNCTION, AND INFECTION. J Parasitol 2003; 89:1048-52. [PMID: 14627155 DOI: 10.1645/ge-3161] [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] [Indexed: 11/10/2022] Open
Abstract
DNA topoisomerases play a pivotal role in the regulation of cell division. Inhibition of Leishmania spp. topoisomerases represents an alternative to control parasite growth. Cancer research led to the development of several potent topoisomerase inhibitors such as topoisomerase I, topoisomerase II, or both (monobenzimidazole, terbenzimidazole, and protoberberine alkaloid-related compounds) that are effective antitumor agents. In the present study, we evaluated the efficacy of these compounds against Leishmania spp. growth in vitro. Some protoberberine compounds showed pronounced antileishmanial activity and were selected for further analysis in macrophages. These compounds did not affect macrophage viability and only slightly reduced macrophage nitric oxide generation in response to interferon-gamma. Moreover, exposure of infected macrophages to these compounds significantly reduced parasite loads. Collectively, our data suggest that protoberberine-related compounds have powerful antileishmania action and that minor structural variations among them can substantially improve their activity to restrict Leishmania spp. infection in vitro.
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Affiliation(s)
- Jean-François Marquis
- Département de Biologie Médicale, Faculté de Médecine, Centre de Recherche en Infectiologie du CHUQ, Université Laval, Sainte-Foy, Québec, Canada G1V 4G2
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23
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Hanke T, Ramiro MJ, Trigueros S, Roca J, Larraga V. Cloning, functional analysis and post-transcriptional regulation of a type II DNA topoisomerase from Leishmania infantum. A new potential target for anti-parasite drugs. Nucleic Acids Res 2003; 31:4917-28. [PMID: 12907735 PMCID: PMC169929 DOI: 10.1093/nar/gkg671] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2003] [Revised: 05/08/2003] [Accepted: 05/30/2003] [Indexed: 11/14/2022] Open
Abstract
We identified a type II topoisomerase enzyme from Leishmania infantum, a parasite protozoon causing disease in humans. This protein, named Li topo II, which displays a variable C-terminal end, is located in the kinetoplast. The cloned gene encoding Li-TOP2 compensates for the slow growth of topo II-deficient mutants of Saccharomyces cerevisiae, resulting in a catalytically active DNA topoisomerase in yeast. Analysis of the specific mRNA levels of the Li-TOP2 gene showed variations throughout the parasite cell cycle in synchronized cells as well as between the distinct forms of the parasite. Thus, the enzyme had higher levels of mRNA expression in the highly infective intracellular form of the parasite, the amastigote, than in the extracellular promastigote form, suggesting a relation with the distinct developmental and infectious phases of the protozoon. In addition, western blot analysis showed differences in protein expression between the proliferative and non-proliferative forms of L.infantum promastigotes, which displayed similar levels of mRNA. This indicated possible post-transcriptional regulation mechanisms. The data suggest that Li topo II has a part in DNA decatenation and probably at the initial stages of proliferation in the intracellular form of L.infantum, a parasite that has to proliferate into the host macrophage to survive its hostile environment in its first moments of intracellular infection.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antiprotozoal Agents/pharmacology
- Cell Division/drug effects
- Cell Division/genetics
- Cloning, Molecular
- DNA Topoisomerases, Type II/genetics
- DNA Topoisomerases, Type II/metabolism
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- DNA, Superhelical/chemistry
- DNA, Superhelical/metabolism
- Escherichia coli/genetics
- Fluorescent Antibody Technique
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Enzymologic
- Genetic Complementation Test
- Leishmania infantum/enzymology
- Leishmania infantum/genetics
- Leishmania infantum/growth & development
- Molecular Sequence Data
- Mutation
- Nucleic Acid Conformation
- Phylogeny
- RNA Processing, Post-Transcriptional
- Recombinant Proteins/isolation & purification
- Recombinant Proteins/metabolism
- Saccharomyces cerevisiae/enzymology
- Saccharomyces cerevisiae/genetics
- Sequence Alignment
- Sequence Homology, Amino Acid
- Topoisomerase II Inhibitors
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Affiliation(s)
- Tobias Hanke
- Centro de Investigaciones Biológicas C.S.I.C., Velázquez 144, Madrid 28006, Spain
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24
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Bodley AL, Chakraborty AK, Xie S, Burri C, Shapiro TA. An unusual type IB topoisomerase from African trypanosomes. Proc Natl Acad Sci U S A 2003; 100:7539-44. [PMID: 12810956 PMCID: PMC164622 DOI: 10.1073/pnas.1330762100] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
African trypanosomes are ancient eukaryotes that cause lethal disease in humans and cattle. Available drugs are inadequate and the need for new therapeutic targets is great. Trypanosoma brucei and related pathogens differ strikingly from higher eukaryotes in many aspects of nucleic acid structure and metabolism. We find yet another example of this in their unusual DNA topoisomerase IB. Type IB topoisomerases relieve the supercoils that accumulate during DNA and RNA synthesis, and are of considerable importance as the target for antitumor camptothecins. Dozens of type IB topoisomerases sequenced from eukaryotes, bacteria, and pox viruses are all encoded by a single gene that predictably contains a highly conserved DNA binding domain and C-terminal catalytic domain, linked by a nonconserved hydrophilic region. We find that topoisomerase IB in T. brucei is encoded by two genes: one for the DNA-binding domain and a second for the C-terminal catalytic domain. In keeping with this, highly purified fractions of native T. brucei topoisomerase IB catalytic activity contain two proteins, of 90 and 36 kDa. The native enzyme is conventional in its Mg2+-independence, ability to relax positive and negative supercoils, and inhibition by camptothecin. Camptothecin promotes the formation of a covalent complex between 32P-labeled substrate DNA and the small subunit. This unusual structural organization may provide a missing link in the evolution of type IB enzymes, which are thought to have arisen over time from the fusion of two independent domains. It also provides another basis for the design of selectively toxic drug candidates.
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Affiliation(s)
- Annette L Bodley
- Division of Clinical Pharmacology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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25
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Jayanarayan KG, Dey CS. Overexpression and increased DNA topoisomerase II-like enzyme activity in arsenite resistant Leishmania donovani. Microbiol Res 2003; 158:55-8. [PMID: 12608580 DOI: 10.1078/0944-5013-00177] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Western immunoblot analyses of whole cell lysates probed with a human specific monoclonal anti-topoisomerase IIalpha antibody identified a 190 kDa protein over expressed in the arsenite resistant Leishmania donovani strain. The crude nuclear extract of the resistant strain showed higher topoisomerase II-like enzyme activity. suggesting a possible regulatory role of putative topoisomerase II in arsenite resistant Leishmania.
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Affiliation(s)
- K G Jayanarayan
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160062, India
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26
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Villa H, Otero Marcos AR, Reguera RM, Balaña-Fouce R, García-Estrada C, Pérez-Pertejo Y, Tekwani BL, Myler PJ, Stuart KD, Bjornsti MA, Ordóñez D. A novel active DNA topoisomerase I in Leishmania donovani. J Biol Chem 2003; 278:3521-6. [PMID: 12444094 DOI: 10.1074/jbc.m203991200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A common feature shared by type I DNA topoisomerases is the presence of a "serine, lysine, X, X, tyrosine" motif as conventional enzyme active site. Preliminary data have shown that Leishmania donovani DNA topoisomerase I gene (LdTOP1A) lacked this conserved motif, giving rise to different theories about the reconstitution of an active DNA topoisomerase I in this parasite. We, herein, describe the molecular cloning of a new DNA topoisomerase I gene from L. donovani (LdTOP1B) containing the highly conserved serine, lysine, X, X, tyrosine motif. DNA topoisomerase I activity was detected only when both genes (LdTOP1A and LdTOP1B) were co-expressed in a yeast expression system, suggesting the existence of a dimeric DNA topoisomerase I in Leishmania parasites.
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Affiliation(s)
- Héctor Villa
- Departamento de Farmacologia y Toxicologia (INTOXCAL), Universidad de León, Campus de Vegazana sn, 24071 León, Spain
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27
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Das A, Mandal C, Dasgupta A, Sengupta T, Majumder HK. An insight into the active site of a type I DNA topoisomerase from the kinetoplastid protozoan Leishmania donovani. Nucleic Acids Res 2002; 30:794-802. [PMID: 11809893 PMCID: PMC100284 DOI: 10.1093/nar/30.3.794] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
DNA topoisomerases are ubiquitous enzymes that govern the topological interconversions of DNA thereby playing a key role in many aspects of nucleic acid metabolism. Recently determined crystal structures of topoisomerase fragments, representing nearly all the known subclasses, have been solved. The type IB enzymes are structurally distinct from other known topoisomerases but are similar to a class of enzymes referred to as tyrosine recombinases. A putative topoisomerase I open reading frame from the kinetoplastid Leishmania donovani was reported which shared a substantial degree of homology with type IB topoisomerases but having a variable C-terminus. Here we present a molecular model of the above parasite gene product, using the human topoisomerase I crystal structure in complex with a 22 bp oligonucleotide as a template. Our studies indicate that the overall structure of the parasite protein is similar to the human enzyme; however, major differences occur in the C-terminal loop, which harbors a serine in place of the usual catalytic tyrosine. Most other structural themes common to type IB topoisomerases, including secondary structural folds, hinged clamps that open and close to bind DNA, nucleophilic attack on the scissile DNA strand and formation of a ternary complex with the topoisomerase I inhibitor camptothecin could be visualized in our homology model. The validity of serine acting as the nucleophile in the case of the parasite protein model was corroborated with our biochemical mapping of the active site with topoisomerase I enzyme purified from L.donovani promastigotes.
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Affiliation(s)
- Aditi Das
- Molecular Parasitology Laboratory and Drug Design, Development and Molecular Modelling, Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Calcutta 700032, India
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28
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Taladriz S, Hanke T, Ramiro MJ, García-Díaz M, García De Lacoba M, Blanco L, Larraga V. Nuclear DNA polymerase beta from Leishmania infantum. Cloning, molecular analysis and developmental regulation. Nucleic Acids Res 2001; 29:3822-34. [PMID: 11557814 PMCID: PMC55913 DOI: 10.1093/nar/29.18.3822] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have identified a novel polymerase beta (Pol beta)-like enzyme from Leishmania infantum, a parasite protozoon causing disease in humans. This protein, named Li Pol beta, shows a nuclear localization that contrasts with the mitochondrial localization of Pol beta from Crithidia fasciculata, a closely related parasite, the only polymerase beta described so far in Trypanosomatidae. Li Pol beta, that belongs to the DNA polymerase X family, displays an evolutionarily conserved Pol beta-type DNA polymerase core, in which most of the key residues involved in DNA binding, nucleotide binding, dRPase and polymerization catalysis are conserved. In agreement with this, Li Pol beta, overproduced in Escherichia coli, displayed intrinsic DNA polymerase activity. Cell synchronization experiments showed a correlation between both Li Pol beta mRNA and protein levels along the parasite cell cycle. Analysis of these parameters at the different growth phases of the parasite, from the proliferative (non-infective) logarithmic phase to the non-dividing (highly infectious) stationary phase, showed high levels of Li Pol beta at the infective phase of the parasite. The data suggest a role of Li Pol beta in base excision repair in L.infantum, a parasite usually affected by oxygen stress environments into the macrophage host cells.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Northern
- Cell Cycle/genetics
- Cell Nucleus/enzymology
- Cloning, Molecular
- DNA Polymerase beta/chemistry
- DNA Polymerase beta/genetics
- DNA Polymerase beta/metabolism
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Fluorescent Antibody Technique
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Enzymologic
- Leishmania infantum/enzymology
- Leishmania infantum/genetics
- Leishmania infantum/growth & development
- Molecular Sequence Data
- Protein Conformation
- RNA Stability
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
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Affiliation(s)
- S Taladriz
- Centro de Investigaciones Biológicas, (C.S.I.C), Velázquez, 144. 2800, Madrid, Spain
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29
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Abstract
Protozoan parasites are responsible for a wide range of debilitating and fatal diseases that are proving notoriously difficult to treat. Many of the standard chemotherapies in use today are expensive, have toxic side effects and, in some cases have marginal efficacy because of the emergence of drug-resistant parasites. In the search for more effective treatments, protozoan topoisomerases are now being considered as potential drug targets, building on the clinical success of anticancer and antibacterial agents that target human and bacterial topoisomerases. In this review, Sandra Cheesman explores progress in this relatively new but potentially important field of research.
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Affiliation(s)
- S J Cheesman
- Institute of Cell and Molecular Biology, the University of Edinburgh, Darwin Building, King's Buildings, Mayfield Road, Edinburgh, UK EH9 3JR.
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