1
|
Plasmodium pre-erythrocytic vaccine antigens enhance sterile protection in mice induced by circumsporozoite protein. Infect Immun 2021; 89:e0016521. [PMID: 34310889 DOI: 10.1128/iai.00165-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pre-erythrocytic vaccines prevent malaria by targeting parasites in the clinically silent sporozoite and liver stages and preventing progression to the virulent blood stages. The leading pre-erythrocytic vaccine RTS,S/AS01E (Mosquirix®) entered implementation programs in 2019 and targets the major sporozoite surface antigen called circumsporozoite protein or CSP. However, in phase III clinical trials, RTS,S conferred partial protection with limited durability, indicating a need to improve CSP-based vaccination. Previously, we identified highly expressed liver stage proteins that could potentially be used in combination with CSP and are referred to as pre-erythrocytic vaccine antigens (PEVA). Here, we developed heterologous prime-boost CSP vaccination models to confer partial sterilizing immunity against Plasmodium yoelii (Py)(protein prime/adenovirus 5 (Ad5) boost) and P. berghei (Pb) (DNA prime/Ad5 boost) in mice. When combined as individual antigens with PyCSP, 3 of 8 PyPEVA significantly enhanced sterile protection against sporozoite challenge, compared to PyCSP alone. Similar results were obtained when 3 PbPEVA and PbCSP were combined in a single vaccine regimen. In general, PyCSP antibody responses were similar after CSP alone versus CSP+PEVA vaccinations. Both Py and Pb CSP+PEVA combination vaccines induced robust CD8+ T cell responses including signature IFN-γ increases. In the Pb model system, IFN-γ responses were significantly higher in hepatic than splenic CD8+ T cells. The addition of novel antigens may enhance the degree and duration of sterile protective immunity conferred by a human vaccine such as RTS,S.
Collapse
|
2
|
Ubonprasert S, Jaroensuk J, Pornthanakasem W, Kamonsutthipaijit N, Wongpituk P, Mee-Udorn P, Rungrotmongkol T, Ketchart O, Chitnumsub P, Leartsakulpanich U, Chaiyen P, Maenpuen S. A flap motif in human serine hydroxymethyltransferase is important for structural stabilization, ligand binding, and control of product release. J Biol Chem 2019; 294:10490-10502. [PMID: 31118236 DOI: 10.1074/jbc.ra119.007454] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 05/21/2019] [Indexed: 12/13/2022] Open
Abstract
Human cytosolic serine hydroxymethyltransferase (hcSHMT) is a promising target for anticancer chemotherapy and contains a flexible "flap motif" whose function is yet unknown. Here, using size-exclusion chromatography, analytical ultracentrifugation, small-angle X-ray scattering (SAXS), molecular dynamics (MD) simulations, and ligand-binding and enzyme-kinetic analyses, we studied the functional roles of the flap motif by comparing WT hcSHMT with a flap-deleted variant (hcSHMT/Δflap). We found that deletion of the flap results in a mixture of apo-dimers and holo-tetramers, whereas the WT was mostly in the tetrameric form. MD simulations indicated that the flap stabilizes structural compactness and thereby enhances oligomerization. The hcSHMT/Δflap variant exhibited different catalytic properties in (6S)-tetrahydrofolate (THF)-dependent reactions compared with the WT but had similar activity in THF-independent aldol cleavage of β-hydroxyamino acid. hcSHMT/Δflap was less sensitive to THF inhibition than the WT (Ki of 0.65 and 0.27 mm THF at pH 7.5, respectively), and the THF dissociation constant of the WT was also 3-fold lower than that of hcSHMT/Δflap, indicating that the flap is important for THF binding. hcSHMT/Δflap did not display the burst kinetics observed in the WT. These results indicate that, upon removal of the flap, product release is no longer the rate-limiting step, implying that the flap is important for controlling product release. The findings reported here improve our understanding of the functional roles of the flap motif in hcSHMT and provide fundamental insight into how a flexible loop can be involved in controlling the enzymatic reactions of hcSHMT and other enzymes.
Collapse
Affiliation(s)
- Sakunrat Ubonprasert
- From the Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Juthamas Jaroensuk
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong 21210, Thailand
| | - Wichai Pornthanakasem
- Biomolecular Analysis and Application Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), and
| | | | - Peerapong Wongpituk
- Center of Excellence in Computational Chemistry (CECC), Department of Chemistry, and
| | - Pitchayathida Mee-Udorn
- Bioinformatics and Computational Biology Program, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand, and
| | - Thanyada Rungrotmongkol
- Bioinformatics and Computational Biology Program, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand, and.,Biocatalyst and Environmental Biotechnology Research Unit, Department of Biochemistry, Faculty of Science, and
| | - Onuma Ketchart
- National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency, Pathumthani 12120, Thailand
| | - Penchit Chitnumsub
- Biomolecular Analysis and Application Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), and
| | - Ubolsree Leartsakulpanich
- Biomolecular Analysis and Application Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), and
| | - Pimchai Chaiyen
- From the Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.,School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong 21210, Thailand
| | - Somchart Maenpuen
- Department of Biochemistry, Faculty of Science, Burapha University, Chonburi 20131, Thailand
| |
Collapse
|
3
|
Schwertz G, Witschel MC, Rottmann M, Leartsakulpanich U, Chitnumsub P, Jaruwat A, Amornwatcharapong W, Ittarat W, Schäfer A, Aponte RA, Trapp N, Chaiyen P, Diederich F. Potent Inhibitors ofPlasmodialSerine Hydroxymethyltransferase (SHMT) Featuring a Spirocyclic Scaffold. ChemMedChem 2018; 13:931-943. [DOI: 10.1002/cmdc.201800053] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 02/25/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Geoffrey Schwertz
- Laboratorium für Organische Chemie; ETH Zürich; Vladimir-Prelog-Weg 3 8093 Zürich Switzerland
| | | | - Matthias Rottmann
- Swiss Tropical and Public Health Institute (SwissTPH); Socinstrasse 57 4051 Basel Switzerland
- Universität Basel; Petersplatz 1 4003 Basel Switzerland
| | - Ubolsree Leartsakulpanich
- National Center for Genetic Engineering and Biotechnology; 113 Thailand Science Park, Phahonyothin Road Pathumthani 12120 Thailand
| | - Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology; 113 Thailand Science Park, Phahonyothin Road Pathumthani 12120 Thailand
| | - Aritsara Jaruwat
- National Center for Genetic Engineering and Biotechnology; 113 Thailand Science Park, Phahonyothin Road Pathumthani 12120 Thailand
| | - Watcharee Amornwatcharapong
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science; Mahidol University; 272 Rama VI Road Bangkok 10400 Thailand
| | - Wanwipa Ittarat
- National Center for Genetic Engineering and Biotechnology; 113 Thailand Science Park, Phahonyothin Road Pathumthani 12120 Thailand
| | - Anja Schäfer
- Swiss Tropical and Public Health Institute (SwissTPH); Socinstrasse 57 4051 Basel Switzerland
- Universität Basel; Petersplatz 1 4003 Basel Switzerland
| | | | - Nils Trapp
- Laboratorium für Organische Chemie; ETH Zürich; Vladimir-Prelog-Weg 3 8093 Zürich Switzerland
| | - Pimchai Chaiyen
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science; Mahidol University; 272 Rama VI Road Bangkok 10400 Thailand
- Department of Biomolecular Science and Engineering, School of Biomolecular Science & Engineering; Vidyasirimedhi Institute of Science and Technology (VISTEC); Wangchan Valley Rayong 21210 Thailand
| | - François Diederich
- Laboratorium für Organische Chemie; ETH Zürich; Vladimir-Prelog-Weg 3 8093 Zürich Switzerland
| |
Collapse
|
4
|
Schwertz G, Witschel MC, Rottmann M, Bonnert R, Leartsakulpanich U, Chitnumsub P, Jaruwat A, Ittarat W, Schäfer A, Aponte RA, Charman SA, White KL, Kundu A, Sadhukhan S, Lloyd M, Freiberg GM, Srikumaran M, Siggel M, Zwyssig A, Chaiyen P, Diederich F. Antimalarial Inhibitors Targeting Serine Hydroxymethyltransferase (SHMT) with in Vivo Efficacy and Analysis of their Binding Mode Based on X-ray Cocrystal Structures. J Med Chem 2017; 60:4840-4860. [DOI: 10.1021/acs.jmedchem.7b00008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Geoffrey Schwertz
- Laboratorium für
Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland
| | | | - Matthias Rottmann
- Swiss Tropical and Public Health Institute (SwissTPH), Socinstrasse
57, 4051 Basel, Switzerland
- Universität Basel, Petersplatz 1, 4003 Basel, Switzerland
| | - Roger Bonnert
- Medicines for Malaria Venture, Route de Pré-Bois 20, CH-1215 Geneva, Switzerland
| | - Ubolsree Leartsakulpanich
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Pathumthni 12120, Thailand
| | - Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Pathumthni 12120, Thailand
| | - Aritsara Jaruwat
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Pathumthni 12120, Thailand
| | - Wanwipa Ittarat
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Pathumthni 12120, Thailand
| | - Anja Schäfer
- Swiss Tropical and Public Health Institute (SwissTPH), Socinstrasse
57, 4051 Basel, Switzerland
- Universität Basel, Petersplatz 1, 4003 Basel, Switzerland
| | | | - Susan A. Charman
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Karen L. White
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Abhijit Kundu
- TCG Lifesciences Private Limited, Block BN, Plot 7, Saltlake Electronics Complex, Sector V, Kolkata 700091, West Bengal India
| | - Surajit Sadhukhan
- TCG Lifesciences Private Limited, Block BN, Plot 7, Saltlake Electronics Complex, Sector V, Kolkata 700091, West Bengal India
| | - Mel Lloyd
- Covance Laboratories Ltd., Otley Road, Harrogate HG3 1PY, United Kingdom
| | - Gail M. Freiberg
- Molecular
Characterization, Department R4AE, AbbVie, 1 North Waukegan Road, North Chicago, Illinois 60064-6217, United States
| | - Myron Srikumaran
- Molecular
Characterization, Department R4AE, AbbVie, 1 North Waukegan Road, North Chicago, Illinois 60064-6217, United States
| | - Marc Siggel
- Laboratorium für
Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland
| | - Adrian Zwyssig
- Laboratorium für
Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland
| | - Pimchai Chaiyen
- Department of
Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science Mahidol University, 272 Rama VI Road, Bangkok 10400, Thailand
| | - François Diederich
- Laboratorium für
Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland
| |
Collapse
|
5
|
Witschel MC, Rottmann M, Schwab A, Leartsakulpanich U, Chitnumsub P, Seet M, Tonazzi S, Schwertz G, Stelzer F, Mietzner T, McNamara C, Thater F, Freymond C, Jaruwat A, Pinthong C, Riangrungroj P, Oufir M, Hamburger M, Mäser P, Sanz-Alonso LM, Charman S, Wittlin S, Yuthavong Y, Chaiyen P, Diederich F. Inhibitors of Plasmodial Serine Hydroxymethyltransferase (SHMT): Cocrystal Structures of Pyrazolopyrans with Potent Blood- and Liver-Stage Activities. J Med Chem 2015; 58:3117-30. [DOI: 10.1021/jm501987h] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
| | - Matthias Rottmann
- Swiss Tropical and Public Health Institute (Swiss TPH), Socinstrasse 57, 4051 Basel, Switzerland
- Universität Basel, Petersplatz 1, 4003 Basel, Switzerland
| | - Anatol Schwab
- Laboratorium
für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland
| | - Ubolsree Leartsakulpanich
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani 12120, Thailand
| | - Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani 12120, Thailand
| | - Michael Seet
- Laboratorium
für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland
| | - Sandro Tonazzi
- Laboratorium
für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland
| | - Geoffrey Schwertz
- Laboratorium
für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland
| | - Frank Stelzer
- BASF SE, Carl-Bosch-Strasse
38, 67056 Ludwigshafen, Germany
| | | | - Case McNamara
- California Institute for Biomedical Research (Calibr), 11119 North Torrey Pines Road, Suite 100, La Jolla, California 92037, United States
| | - Frank Thater
- BASF SE, Carl-Bosch-Strasse
38, 67056 Ludwigshafen, Germany
| | - Céline Freymond
- Swiss Tropical and Public Health Institute (Swiss TPH), Socinstrasse 57, 4051 Basel, Switzerland
- Universität Basel, Petersplatz 1, 4003 Basel, Switzerland
| | - Aritsara Jaruwat
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani 12120, Thailand
| | - Chatchadaporn Pinthong
- Department
of Biochemistry and Center of Excellence in Protein Structure and
Function, Faculty of Science, Mahidol University, 272 Rama VI Road, Bangkok 10400, Thailand
| | - Pinpunya Riangrungroj
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani 12120, Thailand
| | - Mouhssin Oufir
- Pharmaceutical
Biology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Matthias Hamburger
- Pharmaceutical
Biology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Pascal Mäser
- Swiss Tropical and Public Health Institute (Swiss TPH), Socinstrasse 57, 4051 Basel, Switzerland
- Universität Basel, Petersplatz 1, 4003 Basel, Switzerland
| | - Laura M. Sanz-Alonso
- Diseases of the
Developing World (DDW), GlaxoSmithKline, C. Severo Ochoa, 2, 28760 Tres Cantos, Spain
| | - Susan Charman
- Centre
for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute (Swiss TPH), Socinstrasse 57, 4051 Basel, Switzerland
- Universität Basel, Petersplatz 1, 4003 Basel, Switzerland
| | - Yongyuth Yuthavong
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani 12120, Thailand
| | - Pimchai Chaiyen
- Department
of Biochemistry and Center of Excellence in Protein Structure and
Function, Faculty of Science, Mahidol University, 272 Rama VI Road, Bangkok 10400, Thailand
| | - François Diederich
- Laboratorium
für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland
| |
Collapse
|
6
|
Lauron EJ, Oakgrove KS, Tell LA, Biskar K, Roy SW, Sehgal RNM. Transcriptome sequencing and analysis of Plasmodium gallinaceum reveals polymorphisms and selection on the apical membrane antigen-1. Malar J 2014; 13:382. [PMID: 25261185 PMCID: PMC4182871 DOI: 10.1186/1475-2875-13-382] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 09/17/2014] [Indexed: 11/15/2022] Open
Abstract
Background Plasmodium erythrocyte invasion genes play a key role in malaria parasite transmission, host-specificity and immuno-evasion. However, the evolution of the genes responsible remains understudied. Investigating these genes in avian malaria parasites, where diversity is particularly high, offers new insights into the processes that confer malaria pathogenesis. These parasites can pose a significant threat to birds and since birds play crucial ecological roles they serve as important models for disease dynamics. Comprehensive knowledge of the genetic factors involved in avian malaria parasite invasion is lacking and has been hampered by difficulties in obtaining nuclear data from avian malaria parasites. Thus the first Illumina-based de novo transcriptome sequencing and analysis of the chicken parasite Plasmodium gallinaceum was performed to assess the evolution of essential Plasmodium genes. Methods White leghorn chickens were inoculated intravenously with erythrocytes containing P. gallinaceum. cDNA libraries were prepared from RNA extracts collected from infected chick blood and sequencing was run on the HiSeq2000 platform. Orthologues identified by transcriptome sequencing were characterized using phylogenetic, ab initio protein modelling and comparative and population-based methods. Results Analysis of the transcriptome identified several orthologues required for intra-erythrocytic survival and erythrocyte invasion, including the rhoptry neck protein 2 (RON2) and the apical membrane antigen-1 (AMA-1). Ama-1 of avian malaria parasites exhibits high levels of genetic diversity and evolves under positive diversifying selection, ostensibly due to protective host immune responses. Conclusion Erythrocyte invasion by Plasmodium parasites require AMA-1 and RON2 interactions. AMA-1 and RON2 of P. gallinaceum are evolutionarily and structurally conserved, suggesting that these proteins may play essential roles for avian malaria parasites to invade host erythrocytes. In addition, host-driven selection presumably results in the high levels of genetic variation found in ama-1 of avian Plasmodium species. These findings have implications for investigating avian malaria epidemiology and population dynamics. Moreover, this work highlights the P. gallinaceum transcriptome as an important public resource for investigating the diversity and evolution of essential Plasmodium genes. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-382) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Elvin J Lauron
- Department of Biology, San Francisco State University, San Francisco, CA 94132, USA.
| | | | | | | | | | | |
Collapse
|
7
|
Chitnumsub P, Ittarat W, Jaruwat A, Noytanom K, Amornwatcharapong W, Pornthanakasem W, Chaiyen P, Yuthavong Y, Leartsakulpanich U. The structure of Plasmodium falciparum serine hydroxymethyltransferase reveals a novel redox switch that regulates its activities. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:1517-27. [PMID: 24914963 PMCID: PMC4051499 DOI: 10.1107/s1399004714005598] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 03/11/2014] [Indexed: 11/10/2022]
Abstract
Plasmodium falciparum serine hydroxymethyltransferase (PfSHMT), an enzyme in the dTMP synthesis cycle, is an antimalarial target because inhibition of its expression or function has been shown to be lethal to the parasite. As the wild-type enzyme could not be crystallized, protein engineering of residues on the surface was carried out. The surface-engineered mutant PfSHMT-F292E was successfully crystallized and its structure was determined at 3 Å resolution. The PfSHMT-F292E structure is a good representation of PfSHMT as this variant revealed biochemical properties similar to those of the wild type. Although the overall structure of PfSHMT is similar to those of other SHMTs, unique features including the presence of two loops and a distinctive cysteine pair formed by Cys125 and Cys364 in the tetrahydrofolate (THF) substrate binding pocket were identified. These structural characteristics have never been reported in other SHMTs. Biochemical characterization and mutation analysis of these two residues confirm that they act as a disulfide/sulfhydryl switch to regulate the THF-dependent catalytic function of the enzyme. This redox switch is not present in the human enzyme, in which the cysteine pair is absent. The data reported here can be further exploited as a new strategy to specifically disrupt the activity of the parasite enzyme without interfering with the function of the human enzyme.
Collapse
Affiliation(s)
- Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand
| | - Wanwipa Ittarat
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand
| | - Aritsara Jaruwat
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand
| | - Krittikar Noytanom
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand
| | - Watcharee Amornwatcharapong
- Department of Biochemistry and Center for Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Wichai Pornthanakasem
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand
| | - Pimchai Chaiyen
- Department of Biochemistry and Center for Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Yongyuth Yuthavong
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand
| | - Ubolsree Leartsakulpanich
- National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand
| |
Collapse
|
8
|
Vitamin B6-dependent enzymes in the human malaria parasite Plasmodium falciparum: a druggable target? BIOMED RESEARCH INTERNATIONAL 2014; 2014:108516. [PMID: 24524072 PMCID: PMC3912857 DOI: 10.1155/2014/108516] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 10/24/2013] [Accepted: 11/28/2013] [Indexed: 11/17/2022]
Abstract
Malaria is a deadly infectious disease which affects millions of people each year in tropical regions. There is no effective vaccine available and the treatment is based on drugs which are currently facing an emergence of drug resistance and in this sense the search for new drug targets is indispensable. It is well established that vitamin biosynthetic pathways, such as the vitamin B6 de novo synthesis present in Plasmodium, are excellent drug targets. The active form of vitamin B6, pyridoxal 5-phosphate, is, besides its antioxidative properties, a cofactor for a variety of essential enzymes present in the malaria parasite which includes the ornithine decarboxylase (ODC, synthesis of polyamines), the aspartate aminotransferase (AspAT, involved in the protein biosynthesis), and the serine hydroxymethyltransferase (SHMT, a key enzyme within the folate metabolism).
Collapse
|
9
|
Heinberg A, Siu E, Stern C, Lawrence EA, Ferdig MT, Deitsch KW, Kirkman LA. Direct evidence for the adaptive role of copy number variation on antifolate susceptibility in Plasmodium falciparum. Mol Microbiol 2013; 88:702-12. [PMID: 23347134 DOI: 10.1111/mmi.12162] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2013] [Indexed: 11/29/2022]
Abstract
Resistance to antimalarials targeting the folate pathway is widespread. GTP-cyclohydrolase (gch1), the first enzyme in this pathway, exhibits extensive copy number variation (CN) in parasite isolates from areas with a history of longstanding antifolate use. Increased CN of gch1 is associated with a greater number of point mutations in enzymes targeted by the antifolates, pyrimethamine and sulphadoxine. While these observations suggest that increases in gch1 CN are an adaptation to drug pressure, changes in CN have not been experimentally demonstrated to directly alter drug susceptibility. To determine if changes in gch1 expression alone modify pyrimethamine sensitivity, we manipulated gch1 CN in several parasite lines to test the effect on drug sensitivity. We report that increases in gch1 CN alter pyrimethamine resistance in most parasites lines. However we find evidence of a detrimental effect of very high levels of gch1 overexpression in parasite lines with high endogenous levels of gch1 expression, revealing the importance of maintaining balance in the folate pathway and implicating changes in gch1 expression in preserving proper metabolic flux. This work expands our understanding of parasite adaptation to drug pressure and provides a possible mechanism for how specific mutations become fixed within parasite populations.
Collapse
Affiliation(s)
- Adina Heinberg
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | | | | | | | | | | | | |
Collapse
|
10
|
Pornthanakasem W, Kongkasuriyachai D, Uthaipibull C, Yuthavong Y, Leartsakulpanich U. Plasmodium serine hydroxymethyltransferase: indispensability and display of distinct localization. Malar J 2012; 11:387. [PMID: 23173711 PMCID: PMC3521198 DOI: 10.1186/1475-2875-11-387] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 11/20/2012] [Indexed: 12/21/2022] Open
Abstract
Background Serine hydroxymethyltransferase (SHMT), a pyridoxal phosphate-dependent enzyme, plays a vital role in the de novo pyrimidine biosynthesis pathway in malaria parasites. Two genes have been identified in Plasmodium spp. encoding a cytosolic SHMT (cSHMT) and putative mitochondria SHMT (mSHMT), but their roles have not been fully investigated. Methods The presence of Plasmodium SHMT isoforms in the intra-erythrocytic stage was assessed based on their gene expression using reverse transcription PCR (RT-PCR). Localization studies of Plasmodium SHMT isoforms were performed by transfection of fluorescent-tagged gene constructs into P. falciparum and expressions of fluorescent fusion proteins in parasites were observed using a laser scanning confocal microscope. Genetic targeting through homologous recombination was used to study the essentiality of SHMT in Plasmodium spp. Results Semi-quantitative RT-PCR revealed the expression of these two genes throughout intra-erythrocytic development. Localization studies using P. falciparum expressing fluorescent-tagged SHMT showed that PfcSHMT-red fluorescent fusion protein (PfcSHMT-DsRed) is localized in the cytoplasm, while PfmSHMT-green fluorescent fusion protein (PfmSHMT-GFP) co-localized with Mitotracker™-labelled mitochondria as predicted. The essentiality of plasmodial cSHMT was inferred from transfection experiments where recovery of viable knock-out parasites was not achieved, unless complemented with a functional equivalent copy of shmt. Conclusions Distinct compartment localizations of PfSHMT were observed between cytoplasmic and mitochondrial isoforms, and evidence was provided for the indispensable role of plasmodial cSHMT indicating it as a valid target for development of novel anti-malarials.
Collapse
Affiliation(s)
- Wichai Pornthanakasem
- National Center for Genetic Engineering and Biotechnology, 113 Phahonyothin Road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | | | | | | | | |
Collapse
|
11
|
Auliff AM, Balu B, Chen N, O’Neil MT, Cheng Q, Adams JH. Functional analysis of Plasmodium vivax dihydrofolate reductase-thymidylate synthase genes through stable transformation of Plasmodium falciparum. PLoS One 2012; 7:e40416. [PMID: 22792308 PMCID: PMC3392216 DOI: 10.1371/journal.pone.0040416] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 06/07/2012] [Indexed: 12/02/2022] Open
Abstract
Mechanisms of drug resistance in Plasmodium vivax have been difficult to study partially because of the difficulties in culturing the parasite in vitro. This hampers monitoring drug resistance and research to develop or evaluate new drugs. There is an urgent need for a novel method to study mechanisms of P. vivax drug resistance. In this paper we report the development and application of the first Plasmodium falciparum expression system to stably express P. vivax dhfr-ts alleles. We used the piggyBac transposition system for the rapid integration of wild-type, single mutant (117N) and quadruple mutant (57L/58R/61M/117T) pvdhfr-ts alleles into the P. falciparum genome. The majority (81%) of the integrations occurred in non-coding regions of the genome; however, the levels of pvdhfr transcription driven by the P. falciparum dhfr promoter were not different between integrants of non-coding and coding regions. The integrated quadruple pvdhfr mutant allele was much less susceptible to antifolates than the wild-type and single mutant pvdhfr alleles. The resistance phenotype was stable without drug pressure. All the integrated clones were susceptible to the novel antifolate JPC-2067. Therefore, the piggyBac expression system provides a novel and important tool to investigate drug resistance mechanisms and gene functions in P. vivax.
Collapse
Affiliation(s)
- Alyson M. Auliff
- Drug Resistance and Diagnostics Department, Australian Army Malaria Institute, Enoggera, Queensland, Australia
- School of Population Health, University of Queensland, Brisbane, Queensland, Australia
| | - Bharath Balu
- Department of Global Health, University of South Florida, Tampa, Florida, United States of America
| | - Nanhua Chen
- Drug Resistance and Diagnostics Department, Australian Army Malaria Institute, Enoggera, Queensland, Australia
| | - Michael T. O’Neil
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Qin Cheng
- Drug Resistance and Diagnostics Department, Australian Army Malaria Institute, Enoggera, Queensland, Australia
- School of Population Health, University of Queensland, Brisbane, Queensland, Australia
- * E-mail: (JHA); (QC)
| | - John H. Adams
- Department of Global Health, University of South Florida, Tampa, Florida, United States of America
- * E-mail: (JHA); (QC)
| |
Collapse
|
12
|
Sopitthummakhun K, Thongpanchang C, Vilaivan T, Yuthavong Y, Chaiyen P, Leartsakulpanich U. Plasmodium serine hydroxymethyltransferase as a potential anti-malarial target: inhibition studies using improved methods for enzyme production and assay. Malar J 2012; 11:194. [PMID: 22691309 PMCID: PMC3502260 DOI: 10.1186/1475-2875-11-194] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 05/30/2012] [Indexed: 11/21/2022] Open
Abstract
Background There is an urgent need for the discovery of new anti-malarial drugs. Thus, it is essential to explore different potential new targets that are unique to the parasite or that are required for its viability in order to develop new interventions for treating the disease. Plasmodium serine hydroxymethyltransferase (SHMT), an enzyme in the dTMP synthesis cycle, is a potential target for such new drugs, but convenient methods for producing and assaying the enzyme are still lacking, hampering the ability to screen inhibitors. Methods Production of recombinant Plasmodium falciparum SHMT (PfSHMT) and Plasmodium vivax SHMT (PvSHMT), using auto-induction media, were compared to those using the conventional Luria Bertani medium with isopropyl thio-β-D-galactoside (LB-IPTG) induction media. Plasmodium SHMT activity, kinetic parameters, and response to inhibitors were measured spectrophotometrically by coupling the reaction to that of 5,10-methylenetetrahydrofolate dehydrogenase (MTHFD). The identity of the intermediate formed upon inactivation of Plasmodium SHMTs by thiosemicarbazide was investigated by spectrophotometry, high performance liquid chromatography (HPLC), and liquid chromatography-mass spectrometry (LC-MS). The active site environment of Plasmodium SHMT was probed based on changes in the fluorescence emission spectrum upon addition of amino acids and folate. Results Auto-induction media resulted in a two to three-fold higher yield of Pf- and PvSHMT (7.38 and 29.29 mg/L) compared to that produced in cells induced in LB-IPTG media. A convenient spectrophotometric activity assay coupling Plasmodium SHMT and MTHFD gave similar kinetic parameters to those previously obtained from the anaerobic assay coupling SHMT and 5,10-methylenetetrahydrofolate reductase (MTHFR); thus demonstrating the validity of the new assay procedure. The improved method was adopted to screen for Plasmodium SHMT inhibitors, of which some were originally designed as inhibitors of malarial dihydrofolate reductase. Plasmodium SHMT was slowly inactivated by thiosemicarbazide and formed a covalent intermediate, PLP-thiosemicarbazone. Conclusions Auto-induction media offers a cost-effective method for the production of Plasmodium SHMTs and should be applicable for other Plasmodium enzymes. The SHMT-MTHFD coupled assay is equivalent to the SHMT-MTHFR coupled assay, but is more convenient for inhibitor screening and other studies of the enzyme. In addition to inhibitors of malarial SHMT, the development of species-specific, anti-SHMT inhibitors is plausible due to the presence of differential active sites on the Plasmodium enzymes.
Collapse
Affiliation(s)
- Kittipat Sopitthummakhun
- Department of Biochemistry and Center of Excellence in Protein Structure & Function, Faculty of Science, Mahidol University, Rama 6 Road Bangkok 10400, Thailand
| | | | | | | | | | | |
Collapse
|
13
|
Costanzo MS, Brown KM, Hartl DL. Fitness trade-offs in the evolution of dihydrofolate reductase and drug resistance in Plasmodium falciparum. PLoS One 2011; 6:e19636. [PMID: 21625425 PMCID: PMC3100297 DOI: 10.1371/journal.pone.0019636] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 04/10/2011] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Patterns of emerging drug resistance reflect the underlying adaptive landscapes for specific drugs. In Plasmodium falciparum, the parasite that causes the most serious form of malaria, antifolate drugs inhibit the function of essential enzymes in the folate pathway. However, a handful of mutations in the gene coding for one such enzyme, dihydrofolate reductase, confer drug resistance. Understanding how evolution proceeds from drug susceptibility to drug resistance is critical if new antifolate treatments are to have sustained usefulness. METHODOLOGY/PRINCIPAL FINDINGS We use a transgenic yeast expression system to build on previous studies that described the adaptive landscape for the antifolate drug pyrimethamine, and we describe the most likely evolutionary trajectories for the evolution of drug resistance to the antifolate chlorcycloguanil. We find that the adaptive landscape for chlorcycloguanil is multi-peaked, not all highly resistant alleles are equally accessible by evolution, and there are both commonalities and differences in adaptive landscapes for chlorcycloguanil and pyrimethamine. CONCLUSIONS/SIGNIFICANCE Our findings suggest that cross-resistance between drugs targeting the same enzyme reflect the fitness landscapes associated with each particular drug and the position of the genotype on both landscapes. The possible public health implications of these findings are discussed.
Collapse
Affiliation(s)
- Marna S Costanzo
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America.
| | | | | |
Collapse
|
14
|
Torrentino-Madamet M, Alméras L, Desplans J, Le Priol Y, Belghazi M, Pophillat M, Fourquet P, Jammes Y, Parzy D. Global response of Plasmodium falciparum to hyperoxia: a combined transcriptomic and proteomic approach. Malar J 2011; 10:4. [PMID: 21223545 PMCID: PMC3030542 DOI: 10.1186/1475-2875-10-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 01/11/2011] [Indexed: 12/21/2022] Open
Abstract
Background Over its life cycle, the Plasmodium falciparum parasite is exposed to different environmental conditions, particularly to variations in O2 pressure. For example, the parasite circulates in human venous blood at 5% O2 pressure and in arterial blood, particularly in the lungs, at 13% O2 pressure. Moreover, the parasite is exposed to 21% O2 levels in the salivary glands of mosquitoes. Methods To study the metabolic adaptation of P. falciparum to different oxygen pressures during the intraerythrocytic cycle, a combined approach using transcriptomic and proteomic techniques was undertaken. Results Even though hyperoxia lengthens the parasitic cycle, significant transcriptional changes were detected in hyperoxic conditions in the late-ring stage. Using PS 6.0™ software (Ariadne Genomics) for microarray analysis, this study demonstrate up-expression of genes involved in antioxidant systems and down-expression of genes involved in the digestive vacuole metabolism and the glycolysis in favour of mitochondrial respiration. Proteomic analysis revealed increased levels of heat shock proteins, and decreased levels of glycolytic enzymes. Some of this regulation reflected post-transcriptional modifications during the hyperoxia response. Conclusions These results seem to indicate that hyperoxia activates antioxidant defence systems in parasites to preserve the integrity of its cellular structures. Moreover, environmental constraints seem to induce an energetic metabolism adaptation of P. falciparum. This study provides a better understanding of the adaptive capabilities of P. falciparum to environmental changes and may lead to the development of novel therapeutic targets.
Collapse
Affiliation(s)
- Marylin Torrentino-Madamet
- UMR-MD3 (Université de la Méditerranée), Antenne IRBA de Marseille (IMTSSA, Le Pharo), Allée du Médecin Colonel Eugène Jamot, BP 60109, 13262 Marseille cedex 07, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Read M, Müller IB, Mitchell SL, Sims PFG, Hyde JE. Dynamic subcellular localization of isoforms of the folate pathway enzyme serine hydroxymethyltransferase (SHMT) through the erythrocytic cycle of Plasmodium falciparum. Malar J 2010; 9:351. [PMID: 21129192 PMCID: PMC3014972 DOI: 10.1186/1475-2875-9-351] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 12/03/2010] [Indexed: 11/10/2022] Open
Abstract
Background The folate pathway enzyme serine hydroxymethyltransferase (SHMT) converts serine to glycine and 5,10-methylenetetrahydrofolate and is essential for the acquisition of one-carbon units for subsequent transfer reactions. 5,10-methylenetetrahydrofolate is used by thymidylate synthase to convert dUMP to dTMP for DNA synthesis. In Plasmodium falciparum an enzymatically functional SHMT (PfSHMTc) and a related, apparently inactive isoform (PfSHMTm) are found, encoded by different genes. Here, patterns of localization of the two isoforms during the parasite erythrocytic cycle are investigated. Methods Polyclonal antibodies were raised to PfSHMTc and PfSHMTm, and, together with specific markers for the mitochondrion and apicoplast, were employed in quantitative confocal fluorescence microscopy of blood-stage parasites. Results As well as the expected cytoplasmic occupancy of PfSHMTc during all stages, localization into the mitochondrion and apicoplast occurred in a stage-specific manner. Although early trophozoites lacked visible organellar PfSHMTc, a significant percentage of parasites showed such fluorescence during the mid-to-late trophozoite and schizont stages. In the case of the mitochondrion, the majority of parasites in these stages at any given time showed no marked PfSHMTc fluorescence, suggesting that its occupancy of this organelle is of limited duration. PfSHMTm showed a distinctly more pronounced mitochondrial location through most of the erythrocytic cycle and GFP-tagging of its N-terminal region confirmed the predicted presence of a mitochondrial signal sequence. Within the apicoplast, a majority of mitotic schizonts showed a marked concentration of PfSHMTc, whose localization in this organelle was less restricted than for the mitochondrion and persisted from the late trophozoite to the post-mitotic stages. PfSHMTm showed a broadly similar distribution across the cycle, but with a distinctive punctate accumulation towards the ends of elongating apicoplasts. In very late post-mitotic schizonts, both PfSHMTc and PfSHMTm were concentrated in the central region of the parasite that becomes the residual body on erythrocyte lysis and merozoite release. Conclusions Both PfSHMTc and PfSHMTm show dynamic, stage-dependent localization among the different compartments of the parasite and sequence analysis suggests they may also reversibly associate with each other, a factor that may be critical to folate cofactor function, given the apparent lack of enzymic activity of PfSHMTm.
Collapse
Affiliation(s)
- Martin Read
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | | | | | | | | |
Collapse
|
16
|
Brown KM, Costanzo MS, Xu W, Roy S, Lozovsky ER, Hartl DL. Compensatory mutations restore fitness during the evolution of dihydrofolate reductase. Mol Biol Evol 2010; 27:2682-90. [PMID: 20576759 PMCID: PMC2981517 DOI: 10.1093/molbev/msq160] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Whether a trade-off exists between robustness and evolvability is an important issue for protein evolution. Although traditional viewpoints have assumed that existing functions must be compromised by the evolution of novel activities, recent research has suggested that existing phenotypes can be robust to the evolution of novel protein functions. Enzymes that are targets of antibiotics that are competitive inhibitors must evolve decreased drug affinity while maintaining their function and sustaining growth. Utilizing a transgenic Saccharomyces cerevisiae model expressing the dihydrofolate reductase (DHFR) enzyme from the malarial parasite Plasmodium falciparum, we examine the robustness of growth rate to drug-resistance mutations. We assay the growth rate and resistance of all 48 combinations of 6 DHFR point mutations associated with increased drug resistance in field isolates of the parasite. We observe no consistent relationship between growth rate and resistance phenotypes among the DHFR alleles. The three evolutionary pathways that dominate DHFR evolution show that mutations with increased resistance can compensate for initial declines in growth rate from previously acquired mutations. In other words, resistance mutations that occur later in evolutionary trajectories can compensate for the fitness consequences of earlier mutations. Our results suggest that high levels of resistance may be selected for without necessarily jeopardizing overall fitness.
Collapse
Affiliation(s)
- Kyle M Brown
- Department of Organismic and Evolutionary Biology, Harvard University, MA, USA.
| | | | | | | | | | | |
Collapse
|
17
|
Kappe SHI, Vaughan AM, Boddey JA, Cowman AF. That Was Then But This Is Now: Malaria Research in the Time of an Eradication Agenda. Science 2010; 328:862-6. [PMID: 20466924 DOI: 10.1126/science.1184785] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
|
18
|
Becker JVW, Mtwisha L, Crampton BG, Stoychev S, van Brummelen AC, Reeksting S, Louw AI, Birkholtz LM, Mancama DT. Plasmodium falciparum spermidine synthase inhibition results in unique perturbation-specific effects observed on transcript, protein and metabolite levels. BMC Genomics 2010; 11:235. [PMID: 20385001 PMCID: PMC2867828 DOI: 10.1186/1471-2164-11-235] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 04/12/2010] [Indexed: 12/02/2022] Open
Abstract
Background Plasmodium falciparum, the causative agent of severe human malaria, has evolved to become resistant to previously successful antimalarial chemotherapies, most notably chloroquine and the antifolates. The prevalence of resistant strains has necessitated the discovery and development of new chemical entities with novel modes-of-action. Although much effort has been invested in the creation of analogues based on existing drugs and the screening of chemical and natural compound libraries, a crucial shortcoming in current Plasmodial drug discovery efforts remains the lack of an extensive set of novel, validated drug targets. A requirement of these targets (or the pathways in which they function) is that they prove essential for parasite survival. The polyamine biosynthetic pathway, responsible for the metabolism of highly abundant amines crucial for parasite growth, proliferation and differentiation, is currently under investigation as an antimalarial target. Chemotherapeutic strategies targeting this pathway have been successfully utilized for the treatment of Trypanosomes causing West African sleeping sickness. In order to further evaluate polyamine depletion as possible antimalarial intervention, the consequences of inhibiting P. falciparum spermidine synthase (PfSpdSyn) were examined on a morphological, transcriptomic, proteomic and metabolic level. Results Morphological analysis of P. falciparum 3D7 following application of the PfSpdSyn inhibitor cyclohexylamine confirmed that parasite development was completely arrested at the early trophozoite stage. This is in contrast to untreated parasites which progressed to late trophozoites at comparable time points. Global gene expression analyses confirmed a transcriptional arrest in the parasite. Several of the differentially expressed genes mapped to the polyamine biosynthetic and associated metabolic pathways. Differential expression of corresponding parasite proteins involved in polyamine biosynthesis was also observed. Most notably, uridine phosphorylase, adenosine deaminase, lysine decarboxylase (LDC) and S-adenosylmethionine synthetase were differentially expressed at the transcript and/or protein level. Several genes in associated metabolic pathways (purine metabolism and various methyltransferases) were also affected. The specific nature of the perturbation was additionally reflected by changes in polyamine metabolite levels. Conclusions This study details the malaria parasite's response to PfSpdSyn inhibition on the transcriptomic, proteomic and metabolic levels. The results corroborate and significantly expand previous functional genomics studies relating to polyamine depletion in this parasite. Moreover, they confirm the role of transcriptional regulation in P. falciparum, particularly in this pathway. The findings promote this essential pathway as a target for antimalarial chemotherapeutic intervention strategies.
Collapse
|
19
|
Waller JC, Akhtar TA, Lara-Núñez A, Gregory JF, McQuinn RP, Giovannoni JJ, Hanson AD. Developmental and feedforward control of the expression of folate biosynthesis genes in tomato fruit. MOLECULAR PLANT 2010; 3:66-77. [PMID: 20085893 DOI: 10.1093/mp/ssp057] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Little is known about how plants regulate their folate content, including whether the expression of folate biosynthesis genes is orchestrated during development or modulated by folate levels. Nor is much known about how folate levels impact the expression of other genes. These points were addressed using wild-type tomato fruit and fruit engineered for high folate content. In wild-type fruit, the expression of genes specifying early steps in folate biosynthesis declined during development but that of other genes did not. In engineered fruit overexpressing foreign GTP cyclohydrolase I and aminodeoxychorismate synthase genes, the expression of the respective endogenous genes did not change, but that of three downstream pathway genes-aminodeoxychorismate lyase, dihydroneopterin aldolase, and mitochondrial folylpolyglutamate synthase-respectively increased by up to 7.8-, 2.8-, and 1.7-fold, apparently in response to the build-up of specific folate pathway metabolites. These results indicate that, in fruit, certain folate pathway genes are developmentally regulated and that certain others are subject to feedforward control by pathway intermediates. Microarray analysis showed that only 14 other transcripts (of 11 000 surveyed) increased in abundance by two-fold or more in high-folate fruit, demonstrating that the induction of folate pathway genes is relatively specific.
Collapse
Affiliation(s)
- Jeffrey C Waller
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
Müller IB, Hyde JE, Wrenger C. Vitamin B metabolism in Plasmodium falciparum as a source of drug targets. Trends Parasitol 2009; 26:35-43. [PMID: 19939733 DOI: 10.1016/j.pt.2009.10.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 09/25/2009] [Accepted: 10/22/2009] [Indexed: 10/20/2022]
Abstract
The malaria parasite Plasmodium falciparum depends primarily on nutrient sources from its human host. Most compounds, such as glucose, purines, amino acids, as well as cofactors and vitamins, are abundantly available in the host cell, and can be readily salvaged by the parasite. However, in some cases the parasite can also synthesize cofactors de novo in reactions that appear to be essential. Importantly, the three biosynthetic pathways that produce vitamins B(1), B(6) and B(9) are absent from the host, but are well established in P. falciparum. This review summarizes and updates the current knowledge of vitamin B de novo synthesis and salvage in P. falciparum and focuses on their potential as targets for drug intervention.
Collapse
Affiliation(s)
- Ingrid B Müller
- Department of Biochemistry, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
| | | | | |
Collapse
|
21
|
Maenpuen S, Sopitthummakhun K, Yuthavong Y, Chaiyen P, Leartsakulpanich U. Characterization of Plasmodium falciparum serine hydroxymethyltransferase-A potential antimalarial target. Mol Biochem Parasitol 2009; 168:63-73. [PMID: 19591881 DOI: 10.1016/j.molbiopara.2009.06.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Revised: 06/02/2009] [Accepted: 06/25/2009] [Indexed: 10/20/2022]
Abstract
Serine hydroxymethyltransferase (SHMT) is a ubiquitous enzyme required for folate recycling and dTMP synthesis. A cDNA encoding Plasmodium falciparum (Pf) SHMT was expressed as a hexa-histidine tagged protein in Escherichia coli BL21-CodonPlus (DE3)-RIL. The protein was purified and the process yielded 3.6 mg protein/l cell culture. Recombinant His(6)-tagged PfSHMT exhibits a visible spectrum characteristic of pyridoxal-5'-phosphate enzyme and catalyzes the reversible conversion of l-serine and tetrahydrofolate (H(4)folate) to glycine and 5,10-methylenetetrahydrofolate (CH(2)-H(4)folate). Steady-state kinetics study indicates that His(6)-tagged PfSHMT catalyzes the reaction by a ternary-complex mechanism. The sequence of substrate binding to the enzyme was also examined by glycine product inhibition. A striking property that is unique for His(6)-tagged PfSHMT is the ability to use D-serine as a substrate in the folate-dependent serine-glycine conversion. Kinetic data in combination with expression result support the proposal of SHMT reaction being a regulatory step for dTMP cycle. This finding suggests that PfSHMT can be a potential target for antimalarial chemotherapy.
Collapse
Affiliation(s)
- Somchart Maenpuen
- Department of Biochemistry and Center for Excellence in Protein Structure & Function, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, Thailand
| | | | | | | | | |
Collapse
|
22
|
Pang CKT, Hunter JH, Gujjar R, Podutoori R, Bowman J, Mudeppa DG, Rathod PK. Catalytic and ligand-binding characteristics of Plasmodium falciparum serine hydroxymethyltransferase. Mol Biochem Parasitol 2009; 168:74-83. [PMID: 19591883 DOI: 10.1016/j.molbiopara.2009.06.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 05/29/2009] [Accepted: 06/25/2009] [Indexed: 11/28/2022]
Abstract
The plant-like, bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) from malaria parasites has been a good target for drug development. Dihydrofolate reductase (DHFR) is inhibited by clinically established antimalarials, pyrimethamine and cycloguanil. Thymidylate synthase (TS) is the target of potent experimental antimalarials such as 5-fluoroorotate and 1843U89. Another enzyme in folate recycling, serine hydroxymethyltransferase (SHMT), produces 5,10-methylenetetrahydrofolate which, in many cells, is required for the de novo, biosynthesis of thymidine and methionine. Thus, the biochemical characterization of malarial SHMT was of interest. The principle, active Plasmodium falciparum SHMT (PfSHMT) was expressed in E. coli and purified using an N-terminal histidine tag. Unlike the plant enzyme, but like the host enzyme, PfSHMT requires the cofactor pyridoxal 5'-phosphate for enzymatic activity. The substrate specificities for serine, tetrahydrofolate, and pyridoxal 5'-phosphate were comparable to those for SHMT from other organisms. Antifolates developed for DHFR and TS inhibited SHMT in the mid-micromolar range, offering insights into the binding preferences of SHMT but clearly leaving room for improved new inhibitors. As previously seen with P. falciparum DHFR-TS, PfSHMT bound its cognate mRNA but not control RNA for actin. RNA binding was not reversed with enzyme substrates. Unlike DHFR-TS, the SHMT RNA-protein interaction was not tight enough to inhibit translation. Another gene PF14_0534, previously proposed to code for an alternate mitochondrial SHMT, was also expressed in E. coli but found to be inactive. This protein, nor DHFR-TS, enhanced the catalytic activity of PfSHMT. The present results set the stage for developing specific, potent inhibitors of SHMT from P. falciparum.
Collapse
Affiliation(s)
- Cullen K T Pang
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | | | | | | | | | | | | |
Collapse
|
23
|
van Brummelen AC, Olszewski KL, Wilinski D, Llinás M, Louw AI, Birkholtz LM. Co-inhibition of Plasmodium falciparum S-adenosylmethionine decarboxylase/ornithine decarboxylase reveals perturbation-specific compensatory mechanisms by transcriptome, proteome, and metabolome analyses. J Biol Chem 2008; 284:4635-46. [PMID: 19073607 DOI: 10.1074/jbc.m807085200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Polyamines are ubiquitous components of all living cells, and their depletion usually causes cytostasis, a strategy employed for treatment of West African trypanosomiasis. To evaluate polyamine depletion as an anti-malarial strategy, cytostasis caused by the co-inhibition of S-adenosylmethionine decarboxylase/ornithine decarboxylase in Plasmodium falciparum was studied with a comprehensive transcriptome, proteome, and metabolome investigation. Highly synchronized cultures were sampled just before and during cytostasis, and a novel zero time point definition was used to enable interpretation of results in lieu of the developmentally regulated control of gene expression in P. falciparum. Transcriptome analysis revealed the occurrence of a generalized transcriptional arrest just prior to the growth arrest due to polyamine depletion. However, the abundance of 538 transcripts was differentially affected and included three perturbation-specific compensatory transcriptional responses as follows: the increased abundance of the transcripts for lysine decarboxylase and ornithine aminotransferase and the decreased abundance of that for S-adenosylmethionine synthetase. Moreover, the latter two compensatory mechanisms were confirmed on both protein and metabolite levels confirming their biological relevance. In contrast with previous reports, the results provide evidence that P. falciparum responds to alleviate the detrimental effects of polyamine depletion via regulation of its transcriptome and subsequently the proteome and metabolome.
Collapse
Affiliation(s)
- Anna C van Brummelen
- Department of Biochemistry, University of Pretoria, Pretoria, Gauteng 0002, South Africa
| | | | | | | | | | | |
Collapse
|
24
|
Ganesan K, Ponmee N, Jiang L, Fowble JW, White J, Kamchonwongpaisan S, Yuthavong Y, Wilairat P, Rathod PK. A genetically hard-wired metabolic transcriptome in Plasmodium falciparum fails to mount protective responses to lethal antifolates. PLoS Pathog 2008; 4:e1000214. [PMID: 19023412 PMCID: PMC2581438 DOI: 10.1371/journal.ppat.1000214] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 10/21/2008] [Indexed: 11/25/2022] Open
Abstract
Genome sequences of Plasmodium falciparum allow for global analysis of drug responses to antimalarial agents. It was of interest to learn how DNA microarrays may be used to study drug action in malaria parasites. In one large, tightly controlled study involving 123 microarray hybridizations between cDNA from isogenic drug-sensitive and drug-resistant parasites, a lethal antifolate (WR99210) failed to over-produce RNA for the genetically proven principal target, dihydrofolate reductase-thymidylate synthase (DHFR-TS). This transcriptional rigidity carried over to metabolically related RNA encoding folate and pyrimidine biosynthesis, as well as to the rest of the parasite genome. No genes were reproducibly up-regulated by more than 2-fold until 24 h after initial drug exposure, even though clonal viability decreased by 50% within 6 h. We predicted and showed that while the parasites do not mount protective transcriptional responses to antifolates in real time, P. falciparum cells transfected with human DHFR gene, and adapted to long-term WR99210 exposure, adjusted the hard-wired transcriptome itself to thrive in the presence of the drug. A system-wide incapacity for changing RNA levels in response to specific metabolic perturbations may contribute to selective vulnerabilities of Plasmodium falciparum to lethal antimetabolites. In addition, such regulation affects how DNA microarrays are used to understand the mode of action of antimetabolites. Traditional knowledge of gene regulation, learned largely from non-pathogenic model organisms such as E. coli, yeast, and mice, suggests that RNA for metabolic pathways are regulated in large part by DNA-binding transcriptional factors that are responsive to cellular metabolic needs. We demonstrate that the malaria-causing Plasmodium falciparum parasites, under lethal drug pressure from an antifolate with a known mechanism of action, are incapable of large reproducible changes in RNA levels for the target pathways, or for any other gene throughout the genome. Small RNA changes, possibly informative of perturbed pathways, can be detected in dying parasites. In addition, significant RNA changes are seen when the hard-wired program, governing RNA levels, itself is altered. Our data formally proves that RNA levels for intermediary metabolism in malaria parasites are largely predetermined. We propose that as a parasite with a complex life cycle travels from one largely predictable intracellular biochemical environment to another, such hard-wiring may be sufficient to manage transcript levels for intermediary metabolism without employing sensory functions. Such a system-wide host–parasite difference in gene regulation may create unexpected pharmacological opportunities when important target pathways are rigid in the parasite but dynamically regulated in host cells.
Collapse
Affiliation(s)
- Karthikeyan Ganesan
- Department of Chemistry and Global Health, University of Washington, Seattle, Washington, United States of America
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Babiker HA, Schneider P. Application of molecular methods for monitoring transmission stages of malaria parasites. Biomed Mater 2008; 3:034007. [PMID: 18708712 DOI: 10.1088/1748-6041/3/3/034007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Recent technical advances in malaria research have allowed specific detection of mRNA of genes that are expressed exclusively in sexual stages (gametocytes) of malaria parasites. The specificity and sensitivity of these techniques were validated on cultured laboratory clones of both human malaria parasites (Plasmodium falciparum) and rodent parasites (P. chabaudi). More recently, quantitative molecular techniques have been developed to quantify these sexual stages and used to monitor gametocyte dynamics and their transmission to mosquitoes. Molecular techniques showed that the infectious reservoir for malaria is larger than expected from previous microscopic studies; individual parasite genotypes within an infection can simultaneously produce infectious gametocytes; gametocyte production can be sustained for several months, and is modulated by environmental factors. The above techniques have empowered approaches for in-depth analysis of the biology of the transmission stages of the parasite and epidemiology of malaria transmission.
Collapse
Affiliation(s)
- Hamza A Babiker
- Biochemistry Department, Faculty of Medicine, Sultan Qaboos University, Alkhod, PO Box 35, Muscat, Oman School of Biological Sciences, University of Edinburgh, UK.
| | | |
Collapse
|
26
|
Cloning and characterization of Plasmodium vivax serine hydroxymethyltransferase. Parasitol Int 2008; 57:223-8. [DOI: 10.1016/j.parint.2007.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 11/02/2007] [Accepted: 11/05/2007] [Indexed: 01/06/2023]
|
27
|
Birkholtz L, van Brummelen A, Clark K, Niemand J, Maréchal E, Llinás M, Louw A. Exploring functional genomics for drug target and therapeutics discovery in Plasmodia. Acta Trop 2008; 105:113-23. [PMID: 18083131 DOI: 10.1016/j.actatropica.2007.10.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Revised: 10/17/2007] [Accepted: 10/30/2007] [Indexed: 02/04/2023]
Abstract
Functional genomics approaches are indispensable tools in the drug discovery arena and have recently attained increased attention in antibacterial drug discovery research. However, the application of functional genomics to post-genomics research of Plasmodia is still in comparatively early stages. Nonetheless, with this genus having the most species sequenced of any eukaryotic organism so far, the Plasmodia could provide unique opportunities for the study of intracellular eukaryotic pathogens. This review presents the status quo of functional genomics of the malaria parasite including descriptions of the transcriptome, proteome and interactome. We provide examples for the in silico mining of the X-ome data sets and illustrate how X-omic data from drug challenged parasites might be used in elucidating amongst others, the mode-of-action of inhibitory compounds, validate potential targets and discover novel targets/therapeutics.
Collapse
|
28
|
Yamasaki M, Tajima M, Yamato O, Hwang SJ, Ohta H, Maede Y. Heat Shock Response of Babesia gibsoni Heat Shock Protein 70. J Parasitol 2008; 94:119-24. [DOI: 10.1645/ge-1279.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
29
|
Sherman IW. References. ADVANCES IN PARASITOLOGY 2008. [DOI: 10.1016/s0065-308x(08)00430-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
30
|
Dittrich S, Mitchell SL, Blagborough AM, Wang Q, Wang P, Sims PFG, Hyde JE. An atypical orthologue of 6-pyruvoyltetrahydropterin synthase can provide the missing link in the folate biosynthesis pathway of malaria parasites. Mol Microbiol 2007; 67:609-18. [PMID: 18093090 PMCID: PMC2229834 DOI: 10.1111/j.1365-2958.2007.06073.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Folate metabolism in malaria parasites is a long-standing, clinical target for chemotherapy and prophylaxis. However, despite determination of the complete genome sequence of the lethal species Plasmodium falciparum, the pathway of de novo folate biosynthesis remains incomplete, as no candidate gene for dihydroneopterin aldolase (DHNA) could be identified. This enzyme catalyses the third step in the well-characterized pathway of plants, bacteria, and those eukaryotic microorganisms capable of synthesizing their own folate. Utilizing bioinformatics searches based on both primary and higher protein structures, together with biochemical assays, we demonstrate that P. falciparum cell extracts lack detectable DHNA activity, but that the parasite possesses an unusual orthologue of 6-pyruvoyltetrahydropterin synthase (PTPS), which simultaneously gives rise to two products in comparable amounts, the predominant of which is 6-hydroxymethyl-7,8-dihydropterin, the substrate for the fourth step in folate biosynthesis (catalysed by 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase; PPPK). This can provide a bypass for the missing DHNA activity and thus a means of completing the biosynthetic pathway from GTP to dihydrofolate. Supported by site-directed mutagenesis experiments, we ascribe the novel catalytic activity of the malarial PTPS to a Cys to Glu change at its active site relative to all previously characterized PTPS molecules, including that of the human host.
Collapse
Affiliation(s)
- Sabine Dittrich
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | | | | | | | | | | | | |
Collapse
|
31
|
Nirmalan N, Flett F, Skinner T, Hyde JE, Sims PFG. Microscale solution isoelectric focusing as an effective strategy enabling containment of hemeoglobin-derived products for high-resolution gel-based analysis of the Plasmodium falciparum proteome. J Proteome Res 2007; 6:3780-7. [PMID: 17696383 PMCID: PMC2632839 DOI: 10.1021/pr070278r] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The high hemeozoin (beta-hemeatin) content of Plasmodium falciparum lysates imposes severe limitations on the analysis of the malarial proteome, in particular compromising the loading capacities of two-dimensional gels. Here we report on the adaptation of a recently developed solution-phase isoelectric focusing-based fractionation technique as a prefractionation strategy for efficient containment of hemeoglobin-derived products and complexity reduction, to facilitate the high-resolution gel-based quantitative analysis of plasmodial lysates.
Collapse
Affiliation(s)
- Niroshini Nirmalan
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Fiona Flett
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Tom Skinner
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - John E. Hyde
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Paul F. G. Sims
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| |
Collapse
|
32
|
Abstract
Synthesis de novo, acquisition by salvage and interconversion of purines and pyrimidines represent the fundamental requirements for their eventual assembly into nucleic acids as nucleotides and the deployment of their derivatives in other biochemical pathways. A small number of drugs targeted to nucleotide metabolism, by virtue of their effect on folate biosynthesis and recycling, have been successfully used against apicomplexan parasites such as Plasmodium and Toxoplasma for many years, although resistance is now a major problem in the prevention and treatment of malaria. Many targets not involving folate metabolism have also been explored at the experimental level. However, the unravelling of the genome sequences of these eukaryotic unicellular organisms, together with increasingly sophisticated molecular analyses, opens up possibilities of introducing new drugs that could interfere with these processes. This review examines the status of established drugs of this type and the potential for further exploiting the vulnerability of apicomplexan human pathogens to inhibition of this key area of metabolism.
Collapse
Affiliation(s)
- John E Hyde
- Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7ND, UK.
| |
Collapse
|
33
|
Gagnon D, Foucher A, Girard I, Ouellette M. Stage specific gene expression and cellular localization of two isoforms of the serine hydroxymethyltransferase in the protozoan parasite Leishmania. Mol Biochem Parasitol 2006; 150:63-71. [PMID: 16876889 DOI: 10.1016/j.molbiopara.2006.06.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 06/22/2006] [Accepted: 06/23/2006] [Indexed: 11/20/2022]
Abstract
Serine hydroxymethyltransferase (SHMT) catalyses the reversible conversion of serine and tetrahydrofolate to glycine and methylene-tetrahydrofolate. The recent completion of the genome sequence of Leishmania major revealed the presence of two genes coding for two isoforms of this protein. In silico analysis showed that one isoform had an extension at its N-terminus and was predicted to localize to the mitochondrion. The situation is different in other kinetoplastid parasites with only one SHMT encoding gene in Trypanosoma cruzi and no SHMT encoding gene in Trypanosoma brucei. The two L. major SHMT genes were cloned in frame with the green fluorescent protein and the resulting fusion proteins showed differential localization: the short form (SHMT-S) was found in the cytosol while the long one (SHMT-L) was found in an organelle that has hallmarks of the parasite mitochondrion. Indeed, SHMT-L had a similar cellular fractionation pattern as the mitochondrial HSP60 as determined by digitonin fractionation. Both SHMT-S and SHMT-L genes were expressed preferentially in the amastigote stage of the parasite and the RNA levels of SHMT-L could be modulated by glycine, serine, and folate. Overexpression of SHMT-S increased resistance to the antifolate methotrexate and to a lower level to the inhibitor thiosemicarbazide in a rich folate containing medium. These findings suggest that folate metabolism is compartmentalised in Leishmania and that SHMT RNA levels are responsive to environmental conditions.
Collapse
Affiliation(s)
- Dominic Gagnon
- Centre de Recherche en Infectiologie du Centre de recherche du CHUL, Division de Microbiologie, Faculté de Médecine, Université Laval, Québec, Canada
| | | | | | | |
Collapse
|
34
|
Yuthavong Y, Kamchonwongpaisan S, Leartsakulpanich U, Chitnumsub P. Folate metabolism as a source of molecular targets for antimalarials. Future Microbiol 2006; 1:113-25. [PMID: 17661690 DOI: 10.2217/17460913.1.1.113] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Folate metabolism of the malaria parasites provides two targets for current antimalarials: dihydrofolate reductase and dihydropteroate synthase. Dihydrofolate reductase inhibitors have been used as antimalarials over the past few decades, often in combination with dihydropteroate synthase inhibitors. Resistance to these antifolate drugs developed through mutations in both target enzymes. However, limited mutation possibilities gave opportunities for the development of new drugs. Furthermore, other enzymes in the folate and related pathways are potential new targets that remain to be exploited. These include thymidylate synthase, an enzyme fused with dihydrofolate reductase in the same protein chain, serine hydroxymethyltransferase, methylene tetrahydrofolate dehydrogenase, methionine synthase and enzymes in the glycine cleavage pathway.
Collapse
|
35
|
Balme-Sinibaldi V, Tribodet M, Croizat F, Lefeuvre P, Kerlan C, Jacquot E. Improvement of Potato virus Y (PVY) detection and quantitation using PVY(N)- and PVY(O)-specific real-time RT-PCR assays. J Virol Methods 2006; 134:261-6. [PMID: 16513184 DOI: 10.1016/j.jviromet.2006.01.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Revised: 01/18/2006] [Accepted: 01/23/2006] [Indexed: 11/21/2022]
Abstract
A Potato virus Y (PVY) single nucleotide polymorphism (A/G(2213)), recently identified as a molecular determinant of the tobacco leaf necrosis symptom induced by PVY(N) isolates, has been used as a target to develop two PVY group-specific (PVY(N) and PVY(O)) fluorescent (TaqMan-based) real-time RT-PCR assays. These procedures allow detection, characterisation, and quantitation of a wide range of PVY isolates in samples containing 10(3)-10(8) viral transcripts. Moreover, the high specificity of these two new assays make the simultaneous detection and the reliable quantitation of PVY(N) and PVY(O) isolates in mixed solutions, regardless of the Y(N)/Y(O) ratio, feasible. The high sensitivity (threshold of 10(3) copies per reaction) and the PVY group specificity of these two new PVY detection tools clearly improve previously published PVY detection tests and offer new opportunities for PVY research programs.
Collapse
Affiliation(s)
- Valérie Balme-Sinibaldi
- INRA/ENSA, Unité Mixte de Recherche Biologie des Organismes et des Populations Appliquée à la Protection des Plantes (BiO3P), Domaine de la Motte B.P. 35327, F-35653 Le Rheu Cedex, France
| | | | | | | | | | | |
Collapse
|
36
|
Wargo AR, Randle N, Chan BHK, Thompson J, Read AF, Babiker HA. Plasmodium chabaudi: reverse transcription PCR for the detection and quantification of transmission stage malaria parasites. Exp Parasitol 2005; 112:13-20. [PMID: 16256988 DOI: 10.1016/j.exppara.2005.08.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Revised: 08/22/2005] [Accepted: 08/23/2005] [Indexed: 11/28/2022]
Abstract
We have developed two reverse transcription polymerase chain reaction (RT-PCR) techniques to detect and quantify the transmission stages (gametocytes) of Plasmodium chabaudi malaria parasites. Both the qualitative and quantitative techniques are based on the amplification of mRNA coding for the P. chabaudi protein Pcs230, which is expressed exclusively in gametocytes. The quantitative RT-PCR (qRT-PCR) technique was developed and validated by examining serial dilutions of known gametocyte densities. The method generated a high correlation between calibration curves of blind samples (R(2)=0.86). The technique was found to be specific, reproducible, and time efficient for quantification of both patent and sub-patent gametocytemia with a sensitivity level 100-1000 times greater than microscopy. The qualitative RT-PCR (RT-PCR) technique was used to monitor the persistence and dynamics of P. chabaudi gametocytes following acute infection. Mice in two independent experiments were sampled for up to 87 days post-infection. RT-PCR showed that gametocytes can persist for up to 8 weeks, post-infection, whereas microscopy could only detect gametocytes up to 6 weeks. Potential applications of the above techniques for studying the ecology, evolution, and epidemiology of malaria transmission are discussed.
Collapse
Affiliation(s)
- Andrew R Wargo
- Institutes of Evolution, Immunology and Infection Research, Ashworth Laboratories, School of Biological Science, University of Edinburgh, The Kings Buildings, West Mains Road, Edinburgh EH9 3JT, UK.
| | | | | | | | | | | |
Collapse
|
37
|
Abstract
As in centuries past, the main weapon against human malaria infections continues to be intervention with drugs, despite the widespread and increasing frequency of parasite populations that are resistant to one or more of the available compounds. This is a particular problem with the lethal species of parasite, Plasmodium falciparum, which claims some two million lives per year as well as causing enormous social and economic problems. Amongst the antimalarial drugs currently in clinical use, the antifolates have the best defined molecular targets, namely the enzymes dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS), which function in the folate metabolic pathway. The products of this pathway, reduced folate cofactors, are essential for DNA synthesis and the metabolism of certain amino acids. Moreover, their formation and interconversions involve a number of other enzymes that have not as yet been exploited as drug targets. Antifolates are of major importance as they currently represent the only inexpensive regime for combating chloroquine-resistant malaria, and are now first-line drugs in a number of African countries. Aspects of our understanding of this pathway and antifolate drug resistance are reviewed here, with a particular emphasis on approaches to analysing the details of, and balance between, folate biosynthesis by the parasite and salvage of pre-formed folate from exogenous sources.
Collapse
Affiliation(s)
- John E Hyde
- Faculty of life Sciences, University of Manchester, P.O. Box 88, Manchester M60 1QD, UK.
| |
Collapse
|
38
|
Nzila A, Ward SA, Marsh K, Sims PFG, Hyde JE. Comparative folate metabolism in humans and malaria parasites (part I): pointers for malaria treatment from cancer chemotherapy. Trends Parasitol 2005; 21:292-8. [PMID: 15922251 PMCID: PMC2720520 DOI: 10.1016/j.pt.2005.04.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 02/10/2005] [Accepted: 04/11/2005] [Indexed: 12/16/2022]
Abstract
New inhibitors are urgently needed to overcome the burgeoning problem of drug resistance in the treatment of Plasmodium falciparum infection. Targeting the folate pathway has proved to be a powerful strategy for drug development against rapidly multiplying systems such as cancer cells and microorganisms. Antifolates have long been used for malaria treatment but, despite their success, much less is known about parasite folate metabolism than about that of the human host. In this article, we focus on folate enzymes used clinically as anticancer drug targets, in addition to those that have potential to be used as drug targets, for which there are inhibitors at various stages of development. We discuss how this information could lead to the identification of new targets in malaria parasites.
Collapse
Affiliation(s)
- Alexis Nzila
- Kenya Medical Research Institute and Wellcome Trust Collaborative Research Program, Wellcome Trust Research Laboratories, PO Box 43640, Nairobi GPO 00100, Kenya.
| | | | | | | | | |
Collapse
|
39
|
Wang P, Nirmalan N, Wang Q, Sims PFG, Hyde JE. Genetic and metabolic analysis of folate salvage in the human malaria parasite Plasmodium falciparum. Mol Biochem Parasitol 2005; 135:77-87. [PMID: 15287589 DOI: 10.1016/j.molbiopara.2004.01.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Antifolate drugs that target the biosynthesis and processing of essential folate cofactors are widely used for treatment of chloroquine-resistant falciparum malaria. Salvage of pre-formed folate can strongly compromise the efficacy of these drugs in vitro and the availability of folate from the human host in natural infections also influences therapeutic outcomes. To investigate how different parasite lines respond to the presence of exogenous folate, we measured the effect of the latter on the susceptibility of parasites to sulfa-drug blockage of folate biosynthesis, utilising the parents and 22 progeny of the HB3-Dd2 genetic cross of Plasmodium falciparum, together with selected unrelated lines. Complete linkage of the folate utilisation phenotype was observed to a DNA sequence of 48.6 kb lying between nucleotide positions 738,489 and 787,058 of chromosome 4 and encompassing the dihydrofolate reductase-thymidylate synthase (dhfr-ts) gene locus. Examination of the putative ORFs on this fragment upstream (3) and downstream (4) of dhfr-ts revealed no plausible candidate genes for folate processing. Similarly, a marked heterogeneity in the 5'-UTR regions of Dd2 and HB3, manifest as a directly repeated 256 bp sequence in the former, also did not correlate with the folate utilisation phenotype nor apparently influence levels of dhfr-ts transcripts or protein products. By contrast, the nature of the coding sequence of the dhfr domain appeared to play a direct role, with the single mutant (S108N) HB3-type utilising folic acid much less efficiently than other allelic variants. We also compared the processing of exogenous folic acid, folinic acid and p-aminobenzoic acid (pABA) in metabolic labelling studies of HB3 and Dd2. These support the view that DHFR is likely to have a low-level folate reductase activity as well as its normal function of reducing dihydrofolate to tetrahydrofolate, and that a significant hurdle in the utilisation of exogenous folic acid is the initial reduction of fully oxidised folic acid to dihydrofolate, an activity that the single mutant enzyme found in HB3 is postulated to perform particularly poorly. This would mirror earlier studies indicating that the DHFR activity of HB3 is also compromised relative to other variants.
Collapse
Affiliation(s)
- Ping Wang
- Department of Biomolecular Sciences, University of Manchester Institute of Science and Technology, P.O. Box 88, Manchester M60 1QD, UK
| | | | | | | | | |
Collapse
|
40
|
Young JA, Winzeler EA. Using expression information to discover new drug and vaccine targets in the malaria parasitePlasmodium falciparum. Pharmacogenomics 2005; 6:17-26. [PMID: 15723602 DOI: 10.1517/14622416.6.1.17] [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: 11/05/2022] Open
Abstract
The recent completion of the malaria parasite Plasmodium falciparum genome has opened the door for applying a variety of genomic-based systems biology approaches that complement existing gene-by-gene methods of investigation. Transcriptomic analyses of P. falciparum using DNA microarrays has allowed for the rapid elucidation of gene function, parasite drug response, and in vivo expression profiles, as well as general mechanisms guiding the parasite life cycle that are vital to disease pathogenesis. The results of these studies have identified promising novel gene targets for the development of new drug and vaccine therapies.
Collapse
Affiliation(s)
- Jason A Young
- The Scripps Research Institute, Department of Cell Biology, ICND 202, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA
| | | |
Collapse
|
41
|
Nozaki T, Ali V, Tokoro M. Sulfur-Containing Amino Acid Metabolism in Parasitic Protozoa. ADVANCES IN PARASITOLOGY 2005; 60:1-99. [PMID: 16230102 DOI: 10.1016/s0065-308x(05)60001-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sulfur-containing amino acids play indispensable roles in a wide variety of biological activities including protein synthesis, methylation, and biosynthesis of polyamines and glutathione. Biosynthesis and catabolism of these amino acids need to be carefully regulated to achieve the requirement of the above-mentioned activities and also to eliminate toxicity attributable to the amino acids. Genome-wide analyses of enzymes involved in the metabolic pathways of sulfur-containing amino acids, including transsulfuration, sulfur assimilatory de novo cysteine biosynthesis, methionine cycle, and degradation, using genome databases available from a variety of parasitic protozoa, reveal remarkable diversity between protozoan parasites and their mammalian hosts. Thus, the sulfur-containing amino acid metabolic pathways are a rational target for the development of novel chemotherapeutic and prophylactic agents against diseases caused by protozoan parasites. These pathways also demonstrate notable heterogeneity among parasites, suggesting that the metabolism of sulfur-containing amino acids reflects the diversity of parasitism among parasite species, and probably influences their biology and pathophysiology such as virulence competence and stress defense.
Collapse
Affiliation(s)
- Tomoyoshi Nozaki
- Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | | | | |
Collapse
|
42
|
Nirmalan N, Sims PFG, Hyde JE. Translational up-regulation of antifolate drug targets in the human malaria parasite Plasmodium falciparum upon challenge with inhibitors. Mol Biochem Parasitol 2004; 136:63-70. [PMID: 15138068 DOI: 10.1016/j.molbiopara.2004.02.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2003] [Revised: 02/11/2004] [Accepted: 02/29/2004] [Indexed: 11/30/2022]
Abstract
The thymidylate cycle in Plasmodium falciparum is essential for cell growth and replication, and dihydrofolate reductase (DHFR), a key enzyme in this cycle, is the target of important antimalarial drugs such as pyrimethamine and cycloguanil. Following previous work, where we found no evidence of upregulation of the dhfr-ts gene upon challenge with pyrimethamine, we investigated the expression at the protein level of the bifunctional gene product, which also carries thymidylate synthase (TS) activity. Challenge of parasite cultures with fluoro-substituted bases that are specific TS inhibitors at levels close to the IC(50) resulted in five to seven-fold increases in enzyme level, as monitored by both DHFR and TS activities, while pyrimethamine and another DHFR-binding inhibitor, WR99210, induced smaller but still significant increases of approximately three-fold. However, when parasites were challenged with tetracycline, an antimalarial not directed at the folate pathway, although an increase was consistently seen above untreated controls, this was at a level of approximately 1.8-fold. These increases reflect enhanced synthesis of the DHFR-TS enzyme, rather than liberation of a latent activity, as they were completely abolished if cultures were pre-incubated with cycloheximide to block de novo protein synthesis. Moreover, none of the above antimalarial drugs was found to significantly alter absolute levels of the dhfr-ts mRNA under the conditions of challenge used. We conclude that, in common with mammalian systems, where a similar phenomenon has been reported, malaria parasites are able to significantly relieve translational constraint when faced with antifolate drug challenge. The data indicate that there is a specific component in addition to a low-level non-specific increment, and that binding to the TS domain of the DHFR-TS protein appears to be better able to relieve this constraint than binding to the DHFR domain.
Collapse
Affiliation(s)
- Niroshini Nirmalan
- Department of Biomolecular Sciences, University of Manchester Institute of Science and Technology (UMIST), P.O. Box 88, Manchester M60 1QD, UK
| | | | | |
Collapse
|
43
|
Nirmalan N, Sims PFG, Hyde JE. Quantitative proteomics of the human malaria parasite Plasmodium falciparum and its application to studies of development and inhibition. Mol Microbiol 2004; 52:1187-99. [PMID: 15130134 DOI: 10.1111/j.1365-2958.2004.04049.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The ability to measure accurately comparative levels of protein expression after drug challenge, metabolic stress, developmental programming or other perturbation represents one of the most important goals in post-genomics malaria research. We describe here a simple and robust quantitative methodology that is ideally suited to in vitro experiments designed to study changes in the proteome of the most important of the human parasites, the lethal species Plasmodium falciparum. The metabolic labelling technique we have developed uses parasite uptake of heavy isotope-containing isoleucine during normal growth followed by two-dimensional separation of individual proteins and mass spectrometry. The method is applicable to essentially each of the approximately 5300 proteins of P. falciparum predicted from the completed genome sequence, permitting facile identification and accurate comparative quantification of labelled peptides from any of these proteins synthesized by in vitro cultures subjected to different stimuli. We demonstrate its application to the study of cell cycle changes, where we observe divergent patterns of protein and reported transcript levels indicative of modulation at the translational level. Our data also provide evidence for significant levels of post-translational modification in the parasite, and we measure differences among variants of phosphoethanolamine N-methyltransferase and actin-I across the cell cycle. We have also monitored parasite responses to equipotent doses of the clinical antimalarial inhibitors pyrimethamine and tetracycline and observed differential effects for a number of proteins unrelated to likely targets of these drugs.
Collapse
Affiliation(s)
- Niroshini Nirmalan
- Department of Biomolecular Sciences, University of Manchester Institute of Science and Technology (UMIST), PO Box 88, Manchester M60 1QD, UK
| | | | | |
Collapse
|
44
|
Sijwali PS, Rosenthal PJ. Gene disruption confirms a critical role for the cysteine protease falcipain-2 in hemoglobin hydrolysis by Plasmodium falciparum. Proc Natl Acad Sci U S A 2004; 101:4384-9. [PMID: 15070727 PMCID: PMC384756 DOI: 10.1073/pnas.0307720101] [Citation(s) in RCA: 228] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Erythrocytic malaria parasites degrade hemoglobin in an acidic food vacuole to acquire free amino acids and maintain parasite homeostasis. Hemoglobin hydrolysis appears to be a cooperative process requiring cysteine proteases (falcipains) and aspartic proteases (plasmepsins), but the specific roles of different enzymes in this process are unknown. We previously showed that falcipain-2 is a major trophozoite food vacuole cysteine protease. To characterize the specific role of falcipain-2, we disrupted the falcipain-2 gene and assessed the effect of this alteration. Falcipain-2-knockout trophozoites had markedly diminished cysteine protease activity and swollen, dark staining food vacuoles, consistent with a block in hemoglobin hydrolysis, as caused by cysteine protease inhibitors. However, more mature stages of knockout parasites were indistinguishable from wild-type parasites and developed normally. The knockout parasites had decreased and delayed expression of falcipain-2, which appeared to be directed by increased transcription of a second copy of the gene (falcipain-2'). Expression of other falcipains and plasmepsins was similar in wild-type and knockout parasites. Compared with wild-type, knockout parasites were about 3 times more sensitive to the cysteine protease inhibitors E-64 and leupeptin, and over 50-fold more sensitive to the aspartic protease inhibitor pepstatin. Our results assign a specific function for falcipain-2, the hydrolysis of hemoglobin in trophozoites. In addition, they highlight the cooperative action of cysteine and aspartic proteases in hemoglobin degradation by malaria parasites.
Collapse
Affiliation(s)
- Puran S Sijwali
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, CA 94143, USA
| | | |
Collapse
|
45
|
Cowman AF, Crabb BS. Functional genomics: identifying drug targets for parasitic diseases. Trends Parasitol 2004; 19:538-43. [PMID: 14580967 DOI: 10.1016/j.pt.2003.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Alan F Cowman
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne 3050, Australia.
| | | |
Collapse
|
46
|
|