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Majhi S, Awasthi BP, Sharma RK, Mitra K. Buparvaquone Induces Ultrastructural and Physiological Alterations Leading to Mitochondrial Dysfunction and Caspase-Independent Apoptotic Cell Death in Leishmania donovani. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2024; 30:521-538. [PMID: 38709559 DOI: 10.1093/mam/ozae034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 02/09/2024] [Accepted: 03/31/2024] [Indexed: 05/08/2024]
Abstract
Leishmaniasis is a neglected tropical disease (endemic in 99 countries) caused by parasitic protozoa of the genus Leishmania. As treatment options are limited, there is an unmet need for new drugs. The hydroxynaphthoquinone class of compounds demonstrates broad-spectrum activity against protozoan parasites. Buparvaquone (BPQ), a member of this class, is the only drug licensed for the treatment of theileriosis. BPQ has shown promising antileishmanial activity but its mode of action is largely unknown. The aim of this study was to evaluate the ultrastructural and physiological effects of BPQ for elucidating the mechanisms underlying the in vitro antiproliferative activity in Leishmania donovani. Transmission and scanning electron microscopy analyses of BPQ-treated parasites revealed ultrastructural effects characteristic of apoptosis-like cell death, which include alterations in the nucleus, mitochondrion, kinetoplast, flagella, and the flagellar pocket. Using flow cytometry, laser scanning confocal microscopy, and fluorometry, we found that BPQ induced caspase-independent apoptosis-like cell death by losing plasma membrane phospholipid asymmetry and cell cycle arrest at sub-G0/G1 phase. Depolarization of the mitochondrial membrane leads to the generation of oxidative stress and impaired ATP synthesis followed by disruption of intracellular calcium homeostasis. Collectively, these findings provide valuable mechanistic insights and demonstrate BPQ's potential for development as an antileishmanial agent.
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Affiliation(s)
- Swetapadma Majhi
- Electron Microscopy Unit, Sophisticated Analytical Instrument Facility and Research, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, Uttar Pradesh 226031, India
- Academy of Scientific and Innovative Research (AcSIR), Sector 19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh 201 002, India
| | - Bhanu Priya Awasthi
- Electron Microscopy Unit, Sophisticated Analytical Instrument Facility and Research, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, Uttar Pradesh 226031, India
- Academy of Scientific and Innovative Research (AcSIR), Sector 19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh 201 002, India
| | - Rakesh Kumar Sharma
- Electron Microscopy Unit, Sophisticated Analytical Instrument Facility and Research, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, Uttar Pradesh 226031, India
- Academy of Scientific and Innovative Research (AcSIR), Sector 19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh 201 002, India
| | - Kalyan Mitra
- Electron Microscopy Unit, Sophisticated Analytical Instrument Facility and Research, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, Uttar Pradesh 226031, India
- Academy of Scientific and Innovative Research (AcSIR), Sector 19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh 201 002, India
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Anuntasomboon P, Siripattanapipong S, Unajak S, Choowongkomon K, Burchmore R, Leelayoova S, Mungthin M, E-kobon T. Identification of a conserved maxicircle and unique minicircles as part of the mitochondrial genome of Leishmania martiniquensis strain PCM3 in Thailand. Parasit Vectors 2022; 15:459. [PMID: 36510327 PMCID: PMC9743726 DOI: 10.1186/s13071-022-05592-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The mitochondrial DNA of trypanosomatids, including Leishmania, is known as kinetoplast DNAs (kDNAs). The kDNAs form networks of hundreds of DNA circles that are evidently interlocked and require complex RNA editing. Previous studies showed that kDNA played a role in drug resistance, adaptation, and survival of Leishmania. Leishmania martiniquensis is one of the most frequently observed species in Thailand, and its kDNAs have not been illustrated. METHODS This study aimed to extract the kDNA sequences from Illumina short-read and PacBio long-read whole-genome sequence data of L. martiniquensis strain PCM3 priorly isolated from the southern province of Thailand. A circular maxicircle DNA was reconstructed by de novo assembly using the SPAdes program, while the minicircle sequences were retrieved and assembled by the rKOMIC tool. The kDNA contigs were confirmed by blasting to the NCBI database, followed by comparative genomic and phylogenetic analysis. RESULTS We successfully constructed the complete circular sequence of the maxicircle (19,008 bp) and 214 classes of the minicircles from L. martiniquensis strain PCM3. The genome comparison and annotation showed that the maxicircle structure of L. martiniquensis strain PCM3 was similar to those of L. enriettii strain LEM3045 (84.29%), L. arabica strain LEM1108 (82.79%), and L. tarentolae (79.2%). Phylogenetic analysis also showed unique evolution of the minicircles of L. martiniquensis strain PCM3 from other examined Leishmania species. CONCLUSIONS This was the first report of the complete maxicircle and 214 minicircles of L. martiniquensis strain PCM3 using integrated whole-genome sequencing data. The information will be helpful for further improvement of diagnosis methods and monitoring genetic diversity changes of this parasite.
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Affiliation(s)
- Pornchai Anuntasomboon
- grid.9723.f0000 0001 0944 049XDepartment of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand ,grid.9723.f0000 0001 0944 049XOmics Center for Agriculture, Bioresources, Food, and Health, Kasetsart University (OmiKU), Bangkok, Thailand
| | - Suradej Siripattanapipong
- grid.10223.320000 0004 1937 0490Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Sasimanas Unajak
- grid.9723.f0000 0001 0944 049XDepartment of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Kiattawee Choowongkomon
- grid.9723.f0000 0001 0944 049XDepartment of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Richard Burchmore
- grid.8756.c0000 0001 2193 314XGlasgow Polyomics, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Saovanee Leelayoova
- grid.10223.320000 0004 1937 0490Department of Parasitology, Phramongkutklao College of Medicine, Bangkok, Thailand
| | - Mathirut Mungthin
- grid.10223.320000 0004 1937 0490Department of Parasitology, Phramongkutklao College of Medicine, Bangkok, Thailand
| | - Teerasak E-kobon
- grid.9723.f0000 0001 0944 049XDepartment of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand ,grid.9723.f0000 0001 0944 049XOmics Center for Agriculture, Bioresources, Food, and Health, Kasetsart University (OmiKU), Bangkok, Thailand
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Cytosolic and Mitochondrial Hsp90 in Cytokinesis, Mitochondrial DNA Replication, and Drug Action in Trypanosoma brucei. Antimicrob Agents Chemother 2021; 65:e0063221. [PMID: 34424040 DOI: 10.1128/aac.00632-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Trypanosoma brucei subspecies cause African sleeping sickness in humans, an infection that is commonly fatal if not treated, and available therapies are limited. Previous studies have shown that heat shock protein 90 (Hsp90) inhibitors have potent and vivid activity against bloodstream-form trypanosomes. Hsp90s are phylogenetically conserved and essential catalysts that function at the crux of cell biology, where they ensure the proper folding of proteins and their assembly into multicomponent complexes. To assess the specificity of Hsp90 inhibitors and further define the role of Hsp90s in African trypanosomes, we used RNA interference (RNAi) to knock down cytosolic and mitochondrial Hsp90s (HSP83 and HSP84, respectively). Loss of either protein led to cell death, but the phenotypes were distinctly different. Depletion of cytosolic HSP83 closely mimicked the consequences of chemically depleting Hsp90 activity with inhibitor 17-AAG. In these cells, cytokinesis was severely disrupted, and segregation of the kinetoplast (the massive mitochondrial DNA structure unique to this family of eukaryotic pathogens) was impaired, leading to cells with abnormal kinetoplast DNA (kDNA) structures. Quite differently, knockdown of mitochondrial HSP84 did not impair cytokinesis but halted the initiation of new kDNA synthesis, generating cells without kDNA. These findings highlight the central role of Hsp90s in chaperoning cell cycle regulators in trypanosomes, reveal their unique function in kinetoplast replication, and reinforce their specificity and value as drug targets.
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Miller JC, Delzell SB, Concepción-Acevedo J, Boucher MJ, Klingbeil MM. A DNA polymerization-independent role for mitochondrial DNA polymerase I-like protein C in African trypanosomes. J Cell Sci 2020; 133:jcs.233072. [PMID: 32079654 DOI: 10.1242/jcs.233072] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 02/10/2020] [Indexed: 01/01/2023] Open
Abstract
Mitochondrial DNA of Trypanosoma brucei and related parasites is a catenated network containing thousands of minicircles and tens of maxicircles, called kinetoplast DNA (kDNA). Replication of a single nucleoid requires at least three DNA polymerase I-like proteins (i.e. POLIB, POLIC and POLID), each showing discrete localizations near the kDNA during S phase. POLIB and POLID have roles in minicircle replication but the specific role of POLIC in kDNA maintenance is less clear. Here, we use an RNA interference (RNAi)-complementation system to dissect the functions of two distinct POLIC regions, i.e. the conserved family A DNA polymerase (POLA) domain and the uncharacterized N-terminal region (UCR). While RNAi complementation with wild-type POLIC restored kDNA content and cell cycle localization of kDNA, active site point mutations in the POLA domain impaired minicircle replication similar to that of POLIB and POLID depletions. Complementation with POLA domain alone abolished the formation of POLIC foci and partially rescued the RNAi phenotype. Furthermore, we provide evidence that the UCR is crucial in cell cycle-dependent protein localization and facilitates proper distribution of progeny networks. This is the first report of a DNA polymerase that impacts on mitochondrial nucleoid distribution.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Jonathan C Miller
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA
| | - Stephanie B Delzell
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA
| | - Jeniffer Concepción-Acevedo
- Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases, 1600 Clifton Road, Atlanta, GA 30329, USA
| | - Michael J Boucher
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94158, USA
| | - Michele M Klingbeil
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA .,Division of Foodborne,Waterborne, and Environmental Diseases, The Institute of Applied Life Sciences, University of Massachusetts, Amherst, MA 01003, USA
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5
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Inventory and Evolution of Mitochondrion-localized Family A DNA Polymerases in Euglenozoa. Pathogens 2020; 9:pathogens9040257. [PMID: 32244644 PMCID: PMC7238167 DOI: 10.3390/pathogens9040257] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 03/29/2020] [Accepted: 03/30/2020] [Indexed: 11/17/2022] Open
Abstract
The order Trypanosomatida has been well studied due to its pathogenicity and the unique biology of the mitochondrion. In Trypanosoma brucei, four DNA polymerases, namely PolIA, PolIB, PolIC, and PolID, related to bacterial DNA polymerase I (PolI), were shown to be localized in mitochondria experimentally. These mitochondrion-localized DNA polymerases are phylogenetically distinct from other family A DNA polymerases, such as bacterial PolI, DNA polymerase gamma (Polγ) in human and yeasts, “plant and protist organellar DNA polymerase (POP)” in diverse eukaryotes. However, the diversity of mitochondrion-localized DNA polymerases in Euglenozoa other than Trypanosomatida is poorly understood. In this study, we discovered putative mitochondrion-localized DNA polymerases in broad members of three major classes of Euglenozoa—Kinetoplastea, Diplonemea, and Euglenida—to explore the origin and evolution of trypanosomatid PolIA-D. We unveiled distinct inventories of mitochondrion-localized DNA polymerases in the three classes: (1) PolIA is ubiquitous across the three euglenozoan classes, (2) PolIB, C, and D are restricted in kinetoplastids, (3) new types of mitochondrion-localized DNA polymerases were identified in a prokinetoplastid and diplonemids, and (4) evolutionarily distinct types of POP were found in euglenids. We finally propose scenarios to explain the inventories of mitochondrion-localized DNA polymerases in Kinetoplastea, Diplonemea, and Euglenida.
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Concepción-Acevedo J, Miller JC, Boucher MJ, Klingbeil MM. Cell cycle localization dynamics of mitochondrial DNA polymerase IC in African trypanosomes. Mol Biol Cell 2018; 29:2540-2552. [PMID: 30133333 PMCID: PMC6254582 DOI: 10.1091/mbc.e18-02-0127] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Trypanosoma brucei has a unique catenated mitochondrial DNA (mtDNA) network called kinetoplast DNA (kDNA). Replication of kDNA occurs once per cell cycle in near synchrony with nuclear S phase and requires the coordination of many proteins. Among these are three essential DNA polymerases (TbPOLIB, IC, and ID). Localization dynamics of these proteins with respect to kDNA replication stages and how they coordinate their functions during replication are not well understood. We previously demonstrated that TbPOLID undergoes dynamic localization changes that are coupled to kDNA replication events. Here, we report the localization of TbPOLIC, a second essential DNA polymerase, and demonstrate the accumulation of TbPOLIC foci at active kDNA replication sites (antipodal sites) during stage II of the kDNA duplication cycle. While TbPOLIC was undetectable by immunofluorescence during other cell cycle stages, steady-state protein levels measured by Western blot remained constant. TbPOLIC foci colocalized with the fraction of TbPOLID that localized to the antipodal sites. However, the partial colocalization of the two essential DNA polymerases suggests a highly dynamic environment at the antipodal sites to coordinate the trafficking of replication proteins during kDNA synthesis. These data indicate that cell cycle-dependent localization is a major regulatory mechanism for essential mtDNA polymerases during kDNA replication.
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Affiliation(s)
| | - Jonathan C Miller
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA 01003
| | - Michael J Boucher
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA 01003
| | - Michele M Klingbeil
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA 01003
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Amodeo S, Jakob M, Ochsenreiter T. Characterization of the novel mitochondrial genome replication factor MiRF172 in Trypanosoma brucei. J Cell Sci 2018; 131:jcs211730. [PMID: 29626111 PMCID: PMC5963845 DOI: 10.1242/jcs.211730] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 03/20/2018] [Indexed: 01/07/2023] Open
Abstract
The unicellular parasite Trypanosoma brucei harbors one mitochondrial organelle with a singular genome called the kinetoplast DNA (kDNA). The kDNA consists of a network of concatenated minicircles and a few maxicircles that form the kDNA disc. More than 30 proteins involved in kDNA replication have been described. However, several mechanistic questions are only poorly understood. Here, we describe and characterize minicircle replication factor 172 (MiRF172), a novel mitochondrial genome replication factor that is essential for cell growth and kDNA maintenance. By performing super-resolution microscopy, we show that MiRF172 is localized to the kDNA disc, facing the region between the genome and the mitochondrial membranes. We demonstrate that depletion of MiRF172 leads to a loss of minicircles and maxicircles. Detailed analysis suggests that MiRF172 is involved in the reattachment of replicated minicircles to the kDNA disc. Furthermore, we provide evidence that the localization of the replication factor MiRF172 not only depends on the kDNA itself, but also on the mitochondrial genome segregation machinery, suggesting an interaction between the two essential entities.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Simona Amodeo
- Institute of Cell Biology, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern CH-3012, Switzerland
| | - Martin Jakob
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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8
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Peña-Diaz P, Vancová M, Resl C, Field MC, Lukeš J. A leucine aminopeptidase is involved in kinetoplast DNA segregation in Trypanosoma brucei. PLoS Pathog 2017; 13:e1006310. [PMID: 28388690 PMCID: PMC5397073 DOI: 10.1371/journal.ppat.1006310] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 04/19/2017] [Accepted: 03/23/2017] [Indexed: 12/29/2022] Open
Abstract
The kinetoplast (k), the uniquely packaged mitochondrial DNA of trypanosomatid protists is formed by a catenated network of minicircles and maxicircles that divide and segregate once each cell cycle. Although many proteins involved in kDNA replication and segregation are now known, several key steps in the replication mechanism remain uncharacterized at the molecular level, one of which is the nabelschnur or umbilicus, a prominent structure which in the mammalian parasite Trypanosoma brucei connects the daughter kDNA networks prior to their segregation. Here we characterize an M17 family leucyl aminopeptidase metalloprotease, termed TbLAP1, which specifically localizes to the kDNA disk and the nabelschur and represents the first described protein found in this structure. We show that TbLAP1 is required for correct segregation of kDNA, with knockdown resulting in delayed cytokinesis and ectopic expression leading to kDNA loss and decreased cell proliferation. We propose that TbLAP1 is required for efficient kDNA division and specifically participates in the separation of daughter kDNA networks.
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Affiliation(s)
- Priscila Peña-Diaz
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
| | - Marie Vancová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Christian Resl
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Mark C. Field
- School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
- Canadian Institute for Advanced Research, Toronto, ON, Canada
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9
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Fernández-Orgiler A, Martínez-Jiménez MI, Alonso A, Alcolea PJ, Requena JM, Thomas MC, Blanco L, Larraga V. A putative Leishmania DNA polymerase theta protects the parasite against oxidative damage. Nucleic Acids Res 2016; 44:4855-70. [PMID: 27131366 PMCID: PMC4889957 DOI: 10.1093/nar/gkw346] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 04/11/2016] [Accepted: 04/14/2016] [Indexed: 12/19/2022] Open
Abstract
Leishmania infantum is a protozoan parasite that is phagocytized by human macrophages. The host macrophages kill the parasite by generating oxidative compounds that induce DNA damage. We have identified, purified and biochemically characterized a DNA polymerase θ from L. infantum (LiPolθ), demonstrating that it is a DNA-dependent DNA polymerase involved in translesion synthesis of 8oxoG, abasic sites and thymine glycol lesions. Stably transfected L. infantum parasites expressing LiPolθ were significantly more resistant to oxidative and interstrand cross-linking agents, e.g. hydrogen peroxide, cisplatin and mitomycin C. Moreover, LiPolθ-overexpressing parasites showed an increased infectivity toward its natural macrophage host. Therefore, we propose that LiPolθ is a translesion synthesis polymerase involved in parasite DNA damage tolerance, to confer resistance against macrophage aggression.
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Affiliation(s)
| | | | - Ana Alonso
- Centro de Investigaciones Biológicas (CSIC), 28040 Madrid, Spain
| | - Pedro J Alcolea
- Centro de Investigaciones Biológicas (CSIC), 28040 Madrid, Spain
| | - Jose M Requena
- Centro de Biología Molecular 'Severo Ochoa' (CSIC-UAM), 28049 Madrid, Spain
| | - María C Thomas
- Instituto de Parasitología y Biomedicina López-Neyra (CSIC), 18100 Granada, Spain
| | - Luis Blanco
- Centro de Biología Molecular 'Severo Ochoa' (CSIC-UAM), 28049 Madrid, Spain
| | - Vicente Larraga
- Centro de Investigaciones Biológicas (CSIC), 28040 Madrid, Spain
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Alkhaldi AAM, Martinek J, Panicucci B, Dardonville C, Zíková A, de Koning HP. Trypanocidal action of bisphosphonium salts through a mitochondrial target in bloodstream form Trypanosoma brucei. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2015; 6:23-34. [PMID: 27054061 PMCID: PMC4805778 DOI: 10.1016/j.ijpddr.2015.12.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/03/2015] [Accepted: 12/07/2015] [Indexed: 12/21/2022]
Abstract
Lipophilic bisphosphonium salts are among the most promising antiprotozoal leads currently under investigation. As part of their preclinical evaluation we here report on their mode of action against African trypanosomes, the etiological agents of sleeping sickness. The bisphosphonium compounds CD38 and AHI-9 exhibited rapid inhibition of Trypanosoma brucei growth, apparently the result of cell cycle arrest that blocked the replication of mitochondrial DNA, contained in the kinetoplast, thereby preventing the initiation of S-phase. Incubation with either compound led to a rapid reduction in mitochondrial membrane potential, and ATP levels decreased by approximately 50% within 1 h. Between 4 and 8 h, cellular calcium levels increased, consistent with release from the depolarized mitochondria. Within the mitochondria, the Succinate Dehydrogenase complex (SDH) was investigated as a target for bisphosphonium salts, but while its subunit 1 (SDH1) was present at low levels in the bloodstream form trypanosomes, the assembled complex was hardly detectable. RNAi knockdown of the SDH1 subunit produced no growth phenotype, either in bloodstream or in the procyclic (insect) forms and we conclude that in trypanosomes SDH is not the target for bisphosphonium salts. Instead, the compounds inhibited ATP production in intact mitochondria, as well as the purified F1 ATPase, to a level that was similar to 1 mM azide. Co-incubation with azide and bisphosphonium compounds did not inhibit ATPase activity more than either product alone. The results show that, in T. brucei, bisphosphonium compounds do not principally act on succinate dehydrogenase but on the mitochondrial FoF1 ATPase. Bisphosphonium salts display highly promising antiprotozoal activity. It has been reported that, in Leishmania, they act on the mitochondrial SDH complex. We show that in Trypanosoma brucei SDH is not essential and not the drug target. Instead, we present strong evidence that the F1F0 ATPase is the target.
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Affiliation(s)
- Abdulsalam A M Alkhaldi
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Jan Martinek
- Institute of Parasitology, Biology Centre & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Brian Panicucci
- Institute of Parasitology, Biology Centre & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | | | - Alena Zíková
- Institute of Parasitology, Biology Centre & Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
| | - Harry P de Koning
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
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11
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Wong RG, Kazane K, Maslov DA, Rogers K, Aphasizhev R, Simpson L. U-insertion/deletion RNA editing multiprotein complexes and mitochondrial ribosomes in Leishmania tarentolae are located in antipodal nodes adjacent to the kinetoplast DNA. Mitochondrion 2015; 25:76-86. [PMID: 26462764 DOI: 10.1016/j.mito.2015.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Revised: 10/05/2015] [Accepted: 10/08/2015] [Indexed: 11/28/2022]
Abstract
We studied the intramitochondrial localization of several multiprotein complexes involved in U-insertion/deletion RNA editing in trypanosome mitochondria. The editing complexes are located in one or two antipodal nodes adjacent to the kinetoplast DNA (kDNA) disk, which are distinct from but associated with the minicircle catenation nodes. In some cases the proteins are in a bilateral sheet configuration. We also found that mitoribosomes have a nodal configuration. This type of organization is consistent with evidence for protein and RNA interactions of multiple editing complexes to form an ~40S editosome and also an interaction of editosomes with mitochondrial ribosomes.
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Affiliation(s)
- Richard G Wong
- Department of Gerontology, Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, United States; Department of Microbiology, Immunology and Molecular Genetics, Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States
| | - Katelynn Kazane
- Multispan Inc., Hayward, CA 94544, United States; Department of Microbiology, Immunology and Molecular Genetics, Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States
| | - Dmitri A Maslov
- Department of Biology, University of California - Riverside, Riverside, CA 92521, United States
| | - Kestrel Rogers
- Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, United States
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA 02118, United States
| | - Larry Simpson
- Department of Microbiology, Immunology and Molecular Genetics, Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States.
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Bienstock RJ, Beard WA, Wilson SH. Phylogenetic analysis and evolutionary origins of DNA polymerase X-family members. DNA Repair (Amst) 2014; 22:77-88. [PMID: 25112931 DOI: 10.1016/j.dnarep.2014.07.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 06/25/2014] [Accepted: 07/09/2014] [Indexed: 01/19/2023]
Abstract
Mammalian DNA polymerase (pol) β is the founding member of a large group of DNA polymerases now termed the X-family. DNA polymerase β has been kinetically, structurally, and biologically well characterized and can serve as a phylogenetic reference. Accordingly, we have performed a phylogenetic analysis to understand the relationship between pol β and other members of the X-family of DNA polymerases. The bacterial X-family DNA polymerases, Saccharomyces cerevisiae pol IV, and four mammalian X-family polymerases appear to be directly related. These enzymes originated from an ancient common ancestor characterized in two Bacillus species. Understanding distinct functions for each of the X-family polymerases, evolving from a common bacterial ancestor is of significant interest in light of the specialized roles of these enzymes in DNA metabolism.
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Affiliation(s)
- Rachelle J Bienstock
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, United States
| | - William A Beard
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, United States
| | - Samuel H Wilson
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, United States.
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Independence from Kinetoplast DNA maintenance and expression is associated with multidrug resistance in Trypanosoma brucei in vitro. Antimicrob Agents Chemother 2014; 58:2925-8. [PMID: 24550326 PMCID: PMC3993240 DOI: 10.1128/aac.00122-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
It is well known that several antitrypanosomatid drugs accumulate in the parasite's mitochondrion, where they often bind to the organellar DNA, the kinetoplast. To what extent this property relates to the mode of action of these compounds has remained largely unquantified. Here we show that single point mutations that remove the dependence of laboratory strains of the sleeping sickness parasite Trypanosoma brucei on a functional kinetoplast result in significant resistance to the diamidine and phenanthridine drug classes.
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14
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Changmai P, Horáková E, Long S, Černotíková-Stříbrná E, McDonald LM, Bontempi EJ, Lukeš J. Both human ferredoxins equally efficiently rescue ferredoxin deficiency in Trypanosoma brucei. Mol Microbiol 2013; 89:135-51. [PMID: 23675735 DOI: 10.1111/mmi.12264] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2013] [Indexed: 11/29/2022]
Abstract
Ferredoxins are highly conserved proteins that function universally as electron transporters. They not only require Fe-S clusters for their own activity, but are also involved in Fe-S formation itself. We identified two homologues of ferredoxin in the genome of the parasitic protist Trypanosoma brucei and named them TbFdxA and TbFdxB. TbFdxA protein, which is homologous to other eukaryotic mitochondrial ferredoxins, is essential in both the procyclic (= insect-transmitted) and bloodstream (mammalian) stage, but is more abundant in the active mitochondrion of the former stage. Depletion of TbFdxA caused disruption of Fe-S cluster biogenesis and lowered the level of intracellular haem. However, TbFdxB, which is present exclusively within kinetoplastid flagellates, was non-essential for the procyclic stage, and double knock-down with TbFdxA showed this was not due to functional redundancy between the two homologues. Heterologous expressions of human orthologues HsFdx1 and HsFdx2 fully rescued the growth and Fe-S-dependent enzymatic activities of TbFdxA knock-down. In both cases, the genuine human import signals allowed efficient import into the T. brucei mitochondrion. Given the huge evolutionary distance between trypanosomes and humans, ferredoxins clearly have ancestral and highly conserved function in eukaryotes and both human orthologues have retained the capacity to participate in Fe-S cluster assembly.
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Affiliation(s)
- Piya Changmai
- Institute of Parasitology, Biology Centre, University of South Bohemia, Branišovská 31, 37005, České Budějovice (Budweis), Czech Republic
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Trypanosoma brucei Tb927.2.6100 is an essential protein associated with kinetoplast DNA. EUKARYOTIC CELL 2013; 12:970-8. [PMID: 23650088 DOI: 10.1128/ec.00352-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The mitochondrial DNA of trypanosomatid protozoa consists of a complex, intercatenated network of tens of maxicircles and thousands of minicircles. This structure, called kinetoplast DNA (kDNA), requires numerous proteins and multiprotein complexes for replication, segregation, and transcription. In this study, we used a proteomic approach to identify proteins that are associated with the kDNA network. We identified a novel protein encoded by Tb927.2.6100 that was present in a fraction enriched for kDNA and colocalized the protein with kDNA by fluorescence microscopy. RNA interference (RNAi) knockdown of its expression resulted in a growth defect and changes in the proportion of kinetoplasts and nuclei in the cell population. RNAi also resulted in shrinkage and loss of the kinetoplasts, loss of maxicircle and minicircle components of kDNA at similar rates, and (perhaps secondarily) loss of edited and pre-edited mRNA. These results indicate that the Tb927.2.6100 protein is essential for the maintenance of kDNA.
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Dual functions of α-ketoglutarate dehydrogenase E2 in the Krebs cycle and mitochondrial DNA inheritance in Trypanosoma brucei. EUKARYOTIC CELL 2012; 12:78-90. [PMID: 23125353 DOI: 10.1128/ec.00269-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The dihydrolipoyl succinyltransferase (E2) of the multisubunit α-ketoglutarate dehydrogenase complex (α-KD) is an essential Krebs cycle enzyme commonly found in the matrices of mitochondria. African trypanosomes developmentally regulate mitochondrial carbohydrate metabolism and lack a functional Krebs cycle in the bloodstream of mammals. We found that despite the absence of a functional α-KD, bloodstream form (BF) trypanosomes express α-KDE2, which localized to the mitochondrial matrix and inner membrane. Furthermore, α-KDE2 fractionated with the mitochondrial genome, the kinetoplast DNA (kDNA), in a complex with the flagellum. A role for α-KDE2 in kDNA maintenance was revealed in α-KDE2 RNA interference (RNAi) knockdowns. Following RNAi induction, bloodstream trypanosomes showed pronounced growth reduction and often failed to equally distribute kDNA to daughter cells, resulting in accumulation of cells devoid of kDNA (dyskinetoplastic) or containing two kinetoplasts. Dyskinetoplastic trypanosomes lacked mitochondrial membrane potential and contained mitochondria of substantially reduced volume. These results indicate that α-KDE2 is bifunctional, both as a metabolic enzyme and as a mitochondrial inheritance factor necessary for the distribution of kDNA networks to daughter cells at cytokinesis.
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Dynamic localization of Trypanosoma brucei mitochondrial DNA polymerase ID. EUKARYOTIC CELL 2012; 11:844-55. [PMID: 22286095 DOI: 10.1128/ec.05291-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Trypanosomes contain a unique form of mitochondrial DNA called kinetoplast DNA (kDNA) that is a catenated network composed of minicircles and maxicircles. Several proteins are essential for network replication, and most of these localize to the antipodal sites or the kinetoflagellar zone. Essential components for kDNA synthesis include three mitochondrial DNA polymerases TbPOLIB, TbPOLIC, and TbPOLID). In contrast to other kDNA replication proteins, TbPOLID was previously reported to localize throughout the mitochondrial matrix. This spatial distribution suggests that TbPOLID requires redistribution to engage in kDNA replication. Here, we characterize the subcellular distribution of TbPOLID with respect to the Trypanosoma brucei cell cycle using immunofluorescence microscopy. Our analyses demonstrate that in addition to the previously reported matrix localization, TbPOLID was detected as discrete foci near the kDNA. TbPOLID foci colocalized with replicating minicircles at antipodal sites in a specific subset of the cells during stages II and III of kDNA replication. Additionally, the TbPOLID foci were stable following the inhibition of protein synthesis, detergent extraction, and DNase treatment. Taken together, these data demonstrate that TbPOLID has a dynamic localization that allows it to be spatially and temporally available to perform its role in kDNA replication.
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