1
|
Feng X, Zhang J, Liu J, Su J, Liu X, Yang M, Peng Y, Yan H, Chen Z. A stable thymidine kinase 1 tetramer for improved quality control of serum level quantification. Clin Chim Acta 2024; 565:119967. [PMID: 39304108 DOI: 10.1016/j.cca.2024.119967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 07/30/2024] [Accepted: 09/11/2024] [Indexed: 09/22/2024]
Abstract
DNA synthesis is a critical process for cell growth and division. In cancer patients, an enzyme called thymidine kinase 1 (TK1) is often elevated in the blood, making it a valuable biomarker for cancer diagnosis and treatment. However, previous studies have shown that recombinant TK1 can exist in unstable mixtures of tetramers and dimers, leading to inconsistent results and potentially affecting accuracy. To address this issue, we hypothesized that incorporating tetrameric coiled-coil peptides could enhance TK1 self-assembly into stable tetramers without requiring additional adenosine triphosphate. In this study, we successfully expressed a recombinant TK1 tetramer protein in the Escherichia coli system. We optimized the induction conditions, significantly increasing protein expression levels, functionality, and solubility. Size exclusion chromatography confirmed the formation of a tetrameric structure in the expressed TK1 protein, with a molecular weight of 127.2 KDa, consistent with our expectations. We also found that the TK1 tetramer exhibited higher affinity with anti-TK1 IgY than wild-type TK1, as shown by enzyme-linked immunosorbent assay experiments. Moreover, the TK1 tetramer demonstrated good stability against heating, freeze-thawing and lyophilization with almost no immunoactivity lost. These findings suggest that recombinant TK1 tetramers have the potential to serve as calibrators in diagnostic assay kits, becoming promising candidates for quality control of clinical laboratory and in vitro diagnostic reagents.
Collapse
Affiliation(s)
- Xiangning Feng
- NMPA Key Laboratory for Quality Monitoring and Evaluation of Vaccines and Biological Products, 1 Sun Yat-Sen University, Guangzhou 510080, China; One Health Center of Excellence for Research and Training, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou 510080, China
| | - Jinsong Zhang
- NMPA Key Laboratory for Quality Monitoring and Evaluation of Vaccines and Biological Products, 1 Sun Yat-Sen University, Guangzhou 510080, China; One Health Center of Excellence for Research and Training, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou 510080, China
| | - Jinsong Liu
- NMPA Key Laboratory for Quality Monitoring and Evaluation of Vaccines and Biological Products, 1 Sun Yat-Sen University, Guangzhou 510080, China; One Health Center of Excellence for Research and Training, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou 510080, China
| | - Jiayue Su
- NMPA Key Laboratory for Quality Monitoring and Evaluation of Vaccines and Biological Products, 1 Sun Yat-Sen University, Guangzhou 510080, China; One Health Center of Excellence for Research and Training, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou 510080, China
| | - Xinrui Liu
- NMPA Key Laboratory for Quality Monitoring and Evaluation of Vaccines and Biological Products, 1 Sun Yat-Sen University, Guangzhou 510080, China; One Health Center of Excellence for Research and Training, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou 510080, China
| | - Mingwei Yang
- NMPA Key Laboratory for Quality Monitoring and Evaluation of Vaccines and Biological Products, 1 Sun Yat-Sen University, Guangzhou 510080, China; One Health Center of Excellence for Research and Training, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou 510080, China
| | - Yuanli Peng
- NMPA Key Laboratory for Quality Monitoring and Evaluation of Vaccines and Biological Products, 1 Sun Yat-Sen University, Guangzhou 510080, China; One Health Center of Excellence for Research and Training, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou 510080, China
| | - Haozhen Yan
- NMPA Key Laboratory for Quality Monitoring and Evaluation of Vaccines and Biological Products, 1 Sun Yat-Sen University, Guangzhou 510080, China; One Health Center of Excellence for Research and Training, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou 510080, China
| | - Zeliang Chen
- NMPA Key Laboratory for Quality Monitoring and Evaluation of Vaccines and Biological Products, 1 Sun Yat-Sen University, Guangzhou 510080, China; One Health Center of Excellence for Research and Training, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou 510080, China; Key Laboratory of Zoonose Prevention and Control at Universities of Inner Mongolia Autonomous Region, Medical College, Inner Mongolia Minzu University, Tongliao 028000, China; Key Laboratory of Livestock Infectious Diseases, Ministry of Education, Shenyang Agricultural University, Shenyang 110866, China.
| |
Collapse
|
2
|
Trenaman A, Tinti M, Atrih A, Horn D. Genome-wide screens connect HD82 loss-of-function to purine analog resistance in African trypanosomes. mSphere 2024; 9:e0036323. [PMID: 38126788 PMCID: PMC10826343 DOI: 10.1128/msphere.00363-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 11/10/2023] [Indexed: 12/23/2023] Open
Abstract
Nucleoside analogs have been used extensively as anti-infective agents, particularly against viral infections, and have long been considered promising anti-parasitic agents. These pro-drugs are metabolized by host-cell, viral, or parasite enzymes prior to incorporation into DNA, thereby inhibiting DNA replication. Here, we report genes that sensitize African trypanosomes to nucleoside analogs, including the guanosine analog, ganciclovir. We applied ganciclovir selective pressure to a trypanosome genome-wide knockdown library, which yielded nucleoside mono- and diphosphate kinases as hits, validating the approach. The two most dominant hits to emerge, however, were Tb927.6.2800 and Tb927.6.2900, which both encode nuclear proteins; the latter of which is HD82, a SAMHD1-related protein and a putative dNTP triphosphohydrolase. We independently confirmed that HD82, which is conserved among the trypanosomatids, can sensitize Trypanosoma brucei to ganciclovir. Since ganciclovir activity depends upon phosphorylation by ectopically expressed viral thymidine kinase, we also tested the adenosine analog, ara-A, that may be fully phosphorylated by native T. brucei kinase(s). Both Tb927.6.2800 and HD82 knockdowns were resistant to this analog. Tb927.6.2800 knockdown increased sensitivity to hydroxyurea, while dNTP analysis indicated that HD82 is indeed a triphosphohydrolase with dATP as the preferred substrate. Our results provide insights into nucleoside/nucleotide metabolism and nucleoside analog metabolism and resistance in trypanosomatids. We suggest that the product of 6.2800 sensitizes cells to purine analogs through DNA repair, while HD82 does so by reducing the native purine pool.IMPORTANCEThere is substantial interest in developing nucleoside analogs as anti-parasitic agents. We used genome-scale genetic screening and discovered two proteins linked to purine analog resistance in African trypanosomes. Our screens also identified two nucleoside kinases required for pro-drug activation, further validating the approach. The top novel hit, HD82, is related to SAMHD1, a mammalian nuclear viral restriction factor. We validated HD82 and localized the protein to the trypanosome nucleus. HD82 appears to sensitize trypanosomes to nucleoside analogs by reducing native pools of nucleotides, providing insights into both nucleoside/nucleotide metabolism and nucleoside analog resistance in trypanosomatids.
Collapse
Affiliation(s)
- Anna Trenaman
- The Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Michele Tinti
- The Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Abdelmadjid Atrih
- Fingerprints Proteomics Facility, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - David Horn
- The Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| |
Collapse
|
3
|
Antequera-Parrilla P, Castillo-Acosta VM, Bosch-Navarrete C, Ruiz-Pérez LM, González-Pacanowska D. A nuclear orthologue of the dNTP triphosphohydrolase SAMHD1 controls dNTP homeostasis and genomic stability in Trypanosoma brucei. Front Cell Infect Microbiol 2023; 13:1241305. [PMID: 37674581 PMCID: PMC10478004 DOI: 10.3389/fcimb.2023.1241305] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/07/2023] [Indexed: 09/08/2023] Open
Abstract
Maintenance of dNTPs pools in Trypanosoma brucei is dependent on both biosynthetic and degradation pathways that together ensure correct cellular homeostasis throughout the cell cycle which is essential for the preservation of genomic stability. Both the salvage and de novo pathways participate in the provision of pyrimidine dNTPs while purine dNTPs are made available solely through salvage. In order to identify enzymes involved in degradation here we have characterized the role of a trypanosomal SAMHD1 orthologue denominated TbHD82. Our results show that TbHD82 is a nuclear enzyme in both procyclic and bloodstream forms of T. brucei. Knockout forms exhibit a hypermutator phenotype, cell cycle perturbations and an activation of the DNA repair response. Furthermore, dNTP quantification of TbHD82 null mutant cells revealed perturbations in nucleotide metabolism with a substantial accumulation of dATP, dCTP and dTTP. We propose that this HD domain-containing protein present in kinetoplastids plays an essential role acting as a sentinel of genomic fidelity by modulating the unnecessary and detrimental accumulation of dNTPs.
Collapse
Affiliation(s)
| | - Víctor M. Castillo-Acosta
- Instituto de Parasitología y Biomedicina “López-Neyra, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Granada, Spain
| | | | | | - Dolores González-Pacanowska
- Instituto de Parasitología y Biomedicina “López-Neyra, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Granada, Spain
| |
Collapse
|
4
|
Paria P, Tassanakajon A. Identification of Potential Druggable Targets and Structure-Based Virtual Screening for Drug-like Molecules against the Shrimp Pathogen Enterocytozoon hepatopenaei. Int J Mol Sci 2023; 24:ijms24021412. [PMID: 36674953 PMCID: PMC9867128 DOI: 10.3390/ijms24021412] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/26/2022] [Accepted: 01/05/2023] [Indexed: 01/13/2023] Open
Abstract
Enterocytozoon hepatopenaei (EHP) causes slow growth syndrome in shrimp, resulting in huge economic losses for the global shrimp industry. Despite worldwide reports, there are no effective therapeutics for controlling EHP infections. In this study, five potential druggable targets of EHP, namely, aquaporin (AQP), cytidine triphosphate (CTP) synthase, thymidine kinase (TK), methionine aminopeptidase2 (MetAP2), and dihydrofolate reductase (DHFR), were identified via functional classification of the whole EHP proteome. The three-dimensional structures of the proteins were constructed using the artificial-intelligence-based program AlphaFold 2. Following the prediction of druggable sites, the ZINC15 and ChEMBL databases were screened against targets using docking-based virtual screening. Molecules with affinity scores ≥ 7.5 and numbers of interactions ≥ 9 were initially selected and subsequently enriched based on their ADMET properties and electrostatic complementarities. Five compounds were finally selected against each target based on their complex stabilities and binding energies. The compounds CHEMBL3703838, CHEMBL2132563, and CHEMBL133039 were selected against AQP; CHEMBL1091856, CHEMBL1162979, and CHEMBL525202 against CTP synthase; CHEMBL4078273, CHEMBL1683320, and CHEMBL3674540 against TK; CHEMBL340488, CHEMBL1966988, and ZINC000828645375 against DHFR; and CHEMBL3913373, ZINC000016682972, and CHEMBL3142997 against MetAP2.The compounds exhibited high stabilities and low binding free energies, indicating their abilities to suppress EHP infections; however, further validation is necessary for determining their efficacy.
Collapse
|
5
|
Decreased glutamate transport in acivicin resistant Leishmania tarentolae. PLoS Negl Trop Dis 2021; 15:e0010046. [PMID: 34914690 PMCID: PMC8718007 DOI: 10.1371/journal.pntd.0010046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 12/30/2021] [Accepted: 12/02/2021] [Indexed: 12/24/2022] Open
Abstract
Studies of drug resistance in the protozoan parasites of the genus Leishmania have been helpful in revealing biochemical pathways as potential drug targets. The chlorinated glutamine analogue acivicin has shown good activity against Leishmania cells and was shown to target several enzymes containing amidotransferase domains. We selected a Leishmania tarentolae clone for acivicin resistance. The genome of this resistant strain was sequenced and the gene coding for the amidotransferase domain-containing GMP synthase was found to be amplified. Episomal expression of this gene in wild-type L. tarentolae revealed a modest role in acivicin resistance. The most prominent defect observed in the resistant mutant was reduced uptake of glutamate, and through competition experiments we determined that glutamate and acivicin, but not glutamine, share the same transporter. Several amino acid transporters (AATs) were either deleted or mutated in the resistant cells. Some contributed to the acivicin resistance phenotype although none corresponded to the main glutamate transporter. Through sequence analysis one AAT on chromosome 22 corresponded to the main glutamate transporter. Episomal expression of the gene coding for this transporter in the resistant mutant restored glutamate transport and acivicin susceptibility. Its genetic knockout led to reduced glutamate transport and acivicin resistance. We propose that acivicin binds covalently to this transporter and as such leads to decreased transport of glutamate and acivicin thus leading to acivicin resistance. Studies of drug resistance in the protozoan parasites of the genus Leishmania have been helpful in revealing biochemical pathways as potential drug targets. Here we report on the characterization at the genomics and metabolomics levels of a L. tarentolae strain made resistant to acivicin, an analogue of glutamine with activity against this parasite. We found that resistance to acivicin is accompanied by a reduced uptake and intracellular levels of glutamate and that both are expected to share the same transporter. Through gene overexpression and disruption studies we identified the main amino acid transporter responsible for glutamate uptake.
Collapse
|
6
|
Yagüe-Capilla M, Castillo-Acosta VM, Bosch-Navarrete C, Ruiz-Pérez LM, González-Pacanowska D. A Mitochondrial Orthologue of the dNTP Triphosphohydrolase SAMHD1 Is Essential and Controls Pyrimidine Homeostasis in Trypanosoma brucei. ACS Infect Dis 2021; 7:318-332. [PMID: 33417760 DOI: 10.1021/acsinfecdis.0c00551] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The maintenance of deoxyribonucleotide triphosphate (dNTP) homeostasis through synthesis and degradation is critical for accurate genomic and mitochondrial DNA replication fidelity. Trypanosoma brucei makes use of both the salvage and de novo pathways for the provision of pyrimidine dNTPs. In this respect, the sterile α motif and histidine-aspartate domain-containing protein 1 (SAMHD1) appears to be the most relevant dNTPase controlling dNTP/deoxynucleoside homeostasis in mammalian cells. Here, we have characterized the role of a unique trypanosomal SAMHD1 orthologue denominated TbHD52. Our results show that TbHD52 is a mitochondrial enzyme essential in bloodstream forms of T. brucei. Knockout cells are pyrimidine auxotrophs that exhibit strong defects in genomic integrity, cell cycle progression, and nuclear DNA and kinetoplast segregation in the absence of extracellular thymidine. The lack of TbHD52 can be counteracted by the overexpression of human dCMP deaminase, an enzyme that is directly involved in dUMP formation yet absent in trypanosomes. Furthermore, the cellular dNTP quantification and metabolomic analysis of TbHD52 null mutants revealed perturbations in the nucleotide metabolism with a substantial accumulation of dCTP and cytosine-derived metabolites while dTTP formation was significantly reduced. We propose that this HD-domain-containing protein unique to kinetoplastids plays an essential role in pyrimidine dNTP homeostasis and contributes to the provision of deoxycytidine required for cellular dTTP biosynthesis.
Collapse
Affiliation(s)
- Miriam Yagüe-Capilla
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Armilla (Granada) 18016, Spain
| | - Víctor M. Castillo-Acosta
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Armilla (Granada) 18016, Spain
| | - Cristina Bosch-Navarrete
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Armilla (Granada) 18016, Spain
| | - Luis Miguel Ruiz-Pérez
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Armilla (Granada) 18016, Spain
| | - Dolores González-Pacanowska
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Armilla (Granada) 18016, Spain
| |
Collapse
|
7
|
Valente M, Vidal AE, González-Pacanowska D. Targeting Kinetoplastid and Apicomplexan Thymidylate Biosynthesis as an Antiprotozoal Strategy. Curr Med Chem 2019; 26:4262-4279. [PMID: 30259810 DOI: 10.2174/0929867325666180926154329] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 03/23/2018] [Accepted: 09/14/2018] [Indexed: 02/04/2023]
Abstract
Kinetoplastid and apicomplexan parasites comprise a group of protozoans responsible for human diseases, with a serious impact on human health and the socioeconomic growth of developing countries. Chemotherapy is the main option to control these pathogenic organisms and nucleotide metabolism is considered a promising area for the provision of antimicrobial therapeutic targets. Impairment of thymidylate (dTMP) biosynthesis severely diminishes the viability of parasitic protozoa and the absence of enzymatic activities specifically involved in the formation of dTMP (e.g. dUTPase, thymidylate synthase, dihydrofolate reductase or thymidine kinase) results in decreased deoxythymidine triphosphate (dTTP) levels and the so-called thymineless death. In this process, the ratio of deoxyuridine triphosphate (dUTP) versus dTTP in the cellular nucleotide pool has a crucial role. A high dUTP/dTTP ratio leads to uracil misincorporation into DNA, the activation of DNA repair pathways, DNA fragmentation and eventually cell death. The essential character of dTMP synthesis has stimulated interest in the identification and development of drugs that specifically block the biochemical steps involved in thymine nucleotide formation. Here, we review the available literature in relation to drug discovery studies targeting thymidylate biosynthesis in kinetoplastid (genera Trypanosoma and Leishmania) and apicomplexan (Plasmodium spp and Toxoplasma gondii) protozoans. The most relevant findings concerning novel inhibitory molecules with antiparasitic activity against these human pathogens are presented herein.
Collapse
Affiliation(s)
- María Valente
- Instituto de Parasitologia y Biomedicina "Lopez-Neyra", Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Antonio E Vidal
- Instituto de Parasitologia y Biomedicina "Lopez-Neyra", Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Dolores González-Pacanowska
- Instituto de Parasitologia y Biomedicina "Lopez-Neyra", Consejo Superior de Investigaciones Científicas, Granada, Spain
| |
Collapse
|
8
|
Contribution of Cytidine Deaminase to Thymidylate Biosynthesis in Trypanosoma brucei: Intracellular Localization and Properties of the Enzyme. mSphere 2019; 4:4/4/e00374-19. [PMID: 31391279 PMCID: PMC6686228 DOI: 10.1128/msphere.00374-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cytidine deaminase (CDA) is a pyrimidine salvage enzyme that catalyzes cytidine and deoxycytidine hydrolytic deamination to yield uridine and deoxyuridine. Here we report the biochemical characterization of Trypanosoma brucei CDA as an enzyme within the tetrameric class of the CDA family that efficiently deaminates cytidine, deoxycytidine, and the nucleoside analogue 5-methyl-2'-deoxycytidine. In line with previous studies, we show that RNA interference (RNAi)-mediated CDA depletion impairs T. brucei proliferation when grown in pyrimidine-deficient medium, while supplementation with thymidine or deoxyuridine restores growth, further underscoring the role of this enzyme in providing deoxyuridine for dUMP formation via thymidine kinase, the substrate required for de novo thymidylate biosynthesis. This observation contrasts with the existence in T. brucei of a dimeric deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase), an essential enzyme that can produce dUMP via the hydrolysis of dUTP/dUDP. Thus, T. brucei dUTPase-null mutants are thymidine auxotrophs, suggesting that dUTPase might have a role in providing dUMP for thymidylate biosynthesis. We show that overexpression of human dCMP deaminase (DCTD), an enzyme that provides directly dUMP through dCMP deamination, does not reverse the lethal phenotype of dUTPase knockout cells, which further supports the notion that in T. brucei, CDA is uniquely involved in providing dUMP, while the main role of dUTPase would be the withdrawal of the excess of dUTP to avoid its incorporation into DNA. Furthermore, we report the mitochondrial localization of CDA, highlighting the importance of this organelle in pyrimidine metabolism.IMPORTANCE Cytidine deaminases (CDAs) catalyze the hydrolytic deamination of cytidine and deoxycytidine in the pyrimidine salvage pathway. In kinetoplastids, pyrimidine metabolism has been extensively studied as a source of potential drug targets, given the fact that many of the enzymes of the pathway are essential. Thymidylate (dTMP) synthesis in Trypanosoma brucei exhibits unique characteristics. Thus, it has been suggested that the production of dUMP, the substrate for dTMP formation, is solely dependent on cytidine deaminase and thymidine kinase. Here we characterize recombinant T. brucei CDA (TbCDA) and present evidence that indeed the alternative route for dUMP formation via deoxyuridine 5'-triphosphate nucleotidohydrolase does not have a prominent role in de novo dTMP formation. Furthermore, we provide a scheme for the compartmentalization of dTMP biosynthesis, taking into account the observation that CDA is located in the mitochondrion, together with available information on the intracellular localization of other enzymes involved in the dTTP biosynthetic pathway.
Collapse
|
9
|
Crozier TWM, Tinti M, Wheeler RJ, Ly T, Ferguson MAJ, Lamond AI. Proteomic Analysis of the Cell Cycle of Procylic Form Trypanosoma brucei. Mol Cell Proteomics 2018; 17:1184-1195. [PMID: 29555687 PMCID: PMC5986242 DOI: 10.1074/mcp.ra118.000650] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 03/01/2018] [Indexed: 12/24/2022] Open
Abstract
We describe a single-step centrifugal elutriation method to produce synchronous Gap1 (G1)-phase procyclic trypanosomes at a scale amenable for proteomic analysis of the cell cycle. Using ten-plex tandem mass tag (TMT) labeling and mass spectrometry (MS)-based proteomics technology, the expression levels of 5325 proteins were quantified across the cell cycle in this parasite. Of these, 384 proteins were classified as cell-cycle regulated and subdivided into nine clusters with distinct temporal regulation. These groups included many known cell cycle regulators in trypanosomes, which validates the approach. In addition, we identify 40 novel cell cycle regulated proteins that are essential for trypanosome survival and thus represent potential future drug targets for the prevention of trypanosomiasis. Through cross-comparison to the TrypTag endogenous tagging microscopy database, we were able to validate the cell-cycle regulated patterns of expression for many of the proteins of unknown function detected in our proteomic analysis. A convenient interface to access and interrogate these data is also presented, providing a useful resource for the scientific community. Data are available via ProteomeXchange with identifier PXD008741 (https://www.ebi.ac.uk/pride/archive/).
Collapse
Affiliation(s)
- Thomas W M Crozier
- From the ‡Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.,§Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Michele Tinti
- From the ‡Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Richard J Wheeler
- ‖Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Tony Ly
- §Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Michael A J Ferguson
- From the ‡Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK;
| | - Angus I Lamond
- §Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK;
| |
Collapse
|
10
|
Evaluation of the antiprotozoan properties of 5′-norcarbocyclic pyrimidine nucleosides. Bioorg Med Chem Lett 2017; 27:3081-3086. [DOI: 10.1016/j.bmcl.2017.05.052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/15/2017] [Accepted: 05/16/2017] [Indexed: 12/11/2022]
|
11
|
Leija C, Rijo-Ferreira F, Kinch LN, Grishin NV, Nischan N, Kohler JJ, Hu Z, Phillips MA. Pyrimidine Salvage Enzymes Are Essential for De Novo Biosynthesis of Deoxypyrimidine Nucleotides in Trypanosoma brucei. PLoS Pathog 2016; 12:e1006010. [PMID: 27820863 PMCID: PMC5098729 DOI: 10.1371/journal.ppat.1006010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 10/18/2016] [Indexed: 01/17/2023] Open
Abstract
The human pathogenic parasite Trypanosoma brucei possess both de novo and salvage routes for the biosynthesis of pyrimidine nucleotides. Consequently, they do not require salvageable pyrimidines for growth. Thymidine kinase (TK) catalyzes the formation of dTMP and dUMP and is one of several salvage enzymes that appear redundant to the de novo pathway. Surprisingly, we show through analysis of TK conditional null and RNAi cells that TK is essential for growth and for infectivity in a mouse model, and that a catalytically active enzyme is required for its function. Unlike humans, T. brucei and all other kinetoplastids lack dCMP deaminase (DCTD), which provides an alternative route to dUMP formation. Ectopic expression of human DCTD resulted in full rescue of the RNAi growth phenotype and allowed for selection of viable TK null cells. Metabolite profiling by LC-MS/MS revealed a buildup of deoxypyrimidine nucleosides in TK depleted cells. Knockout of cytidine deaminase (CDA), which converts deoxycytidine to deoxyuridine led to thymidine/deoxyuridine auxotrophy. These unexpected results suggested that T. brucei encodes an unidentified 5'-nucleotidase that converts deoxypyrimidine nucleotides to their corresponding nucleosides, leading to their dead-end buildup in TK depleted cells at the expense of dTTP pools. Bioinformatics analysis identified several potential candidate genes that could encode 5'-nucleotidase activity including an HD-domain protein that we show catalyzes dephosphorylation of deoxyribonucleotide 5'-monophosphates. We conclude that TK is essential for synthesis of thymine nucleotides regardless of whether the nucleoside precursors originate from the de novo pathway or through salvage. Reliance on TK in the absence of DCTD may be a shared vulnerability among trypanosomatids and may provide a unique opportunity to selectively target a diverse group of pathogenic single-celled eukaryotes with a single drug.
Collapse
Affiliation(s)
- Christopher Leija
- Department of Pharmacology University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Filipa Rijo-Ferreira
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
- Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Lisa N. Kinch
- Department of Biophysics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Nick V. Grishin
- Department of Biophysics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Nicole Nischan
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Jennifer J. Kohler
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Zeping Hu
- Children’s Medical Center Research Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Margaret A. Phillips
- Department of Pharmacology University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| |
Collapse
|