1
|
Babai R, Izrael R, Vértessy BG. Characterization of the dynamics of Plasmodium falciparum deoxynucleotide-triphosphate pool in a stage-specific manner. Sci Rep 2022; 12:19926. [PMID: 36402851 PMCID: PMC9675800 DOI: 10.1038/s41598-022-23807-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 11/06/2022] [Indexed: 11/21/2022] Open
Abstract
Understanding and characterizing the molecular background of the maintenance of genomic integrity might be a major factor in comprehending the exceptional ability of the malaria parasite, Plasmodium falciparum to adapt at a fast pace to antimalarials. A balanced nucleotide pool is an essential factor for high-fidelity replication. The lack of detailed studies on deoxynucleotide-triphosphate (dNTP) pools in various intraerythrocytic stages of Plasmodium falciparum motivated our present study. Here, we focused on the building blocks of DNA and utilized an EvaGreen-based dNTP incorporation assay to successfully measure the temporal dynamics of dNTPs in every intraerythrocytic stage and in drug-treated trophozoites. Our findings show that the ratio of dNTPs in the ring-stage parasites significantly differs from the more mature trophozoite and schizont stages. We were also able to detect dGTP levels that have never been shown before and found it to be the least abundant dNTP in all stages. Treatment with WR99210, a TS-DHFR inhibitor drug, affected not only dTTP, but also dGTP levels, despite its presumed selective action on pyrimidine biosynthesis. Results from our studies might assist in a better understanding of genome integrity mechanisms and may potentially lead to novel drug related aspects involving purine and pyrimidine metabolic targets.
Collapse
Affiliation(s)
- Réka Babai
- grid.425578.90000 0004 0512 3755Malaria Research Laboratory, Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117 Hungary ,grid.6759.d0000 0001 2180 0451George A. Olah Doctoral School of Chemistry and Chemical Technology, BME Budapest University of Technology and Economics, Budapest, 1111 Hungary ,grid.6759.d0000 0001 2180 0451Department of Applied Biotechnology and Food Sciences, BME Budapest University of Technology and Economics, Budapest, 1111 Hungary
| | - Richard Izrael
- grid.425578.90000 0004 0512 3755Malaria Research Laboratory, Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117 Hungary ,grid.9008.10000 0001 1016 9625Doctoral School of Multidisciplinary Medical Sciences, University of Szeged, Szeged, 6720 Hungary
| | - Beáta G. Vértessy
- grid.425578.90000 0004 0512 3755Malaria Research Laboratory, Institute of Enzymology, Research Centre for Natural Sciences, Budapest, 1117 Hungary ,grid.6759.d0000 0001 2180 0451Department of Applied Biotechnology and Food Sciences, BME Budapest University of Technology and Economics, Budapest, 1111 Hungary
| |
Collapse
|
2
|
Heppler LN, Attarha S, Persaud R, Brown JI, Wang P, Petrova B, Tošić I, Burton FB, Flamand Y, Walker SR, Yeh JE, Zubarev RA, Gaetani M, Kanarek N, Page BDG, Frank DA. The antimicrobial drug pyrimethamine inhibits STAT3 transcriptional activity by targeting the enzyme dihydrofolate reductase. J Biol Chem 2022; 298:101531. [PMID: 34953855 PMCID: PMC8800111 DOI: 10.1016/j.jbc.2021.101531] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 12/13/2021] [Indexed: 12/19/2022] Open
Abstract
Cancer is often characterized by aberrant gene expression patterns caused by the inappropriate activation of transcription factors. Signal transducer and activator of transcription 3 (STAT3) is a key transcriptional regulator of many protumorigenic processes and is persistently activated in many types of human cancer. However, like many transcription factors, STAT3 has proven difficult to target clinically. To address this unmet clinical need, we previously developed a cell-based assay of STAT3 transcriptional activity and performed an unbiased and high-throughput screen of small molecules known to be biologically active in humans. We identified the antimicrobial drug pyrimethamine as a novel and specific inhibitor of STAT3 transcriptional activity. Here, we show that pyrimethamine does not significantly affect STAT3 phosphorylation, nuclear translocation, or DNA binding at concentrations sufficient to inhibit STAT3 transcriptional activity, suggesting a potentially novel mechanism of inhibition. To identify the direct molecular target of pyrimethamine and further elucidate the mechanism of action, we used a new quantitative proteome profiling approach called proteome integral solubility alteration coupled with a metabolomic analysis. We identified human dihydrofolate reductase as a target of pyrimethamine and demonstrated that the STAT3-inhibitory effects of pyrimethamine are the result of a deficiency in reduced folate downstream of dihydrofolate reductase inhibition, implicating folate metabolism in the regulation of STAT3 transcriptional activity. This study reveals a previously unknown regulatory node of the STAT3 pathway that may be important for the development of novel strategies to treat STAT3-driven cancers.
Collapse
Affiliation(s)
- Lisa N Heppler
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA; Division of Medical Sciences, Harvard University, Boston, Massachusetts, USA
| | - Sanaz Attarha
- Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden
| | - Rosanne Persaud
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
| | - Jennifer I Brown
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
| | - Peng Wang
- Department of Pathology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Boryana Petrova
- Department of Pathology, Boston Children's Hospital, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
| | - Isidora Tošić
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Foster B Burton
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Yael Flamand
- Department of Data Sciences, Dana-Farber-Cancer Institute, Boston, Massachusetts, USA
| | - Sarah R Walker
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Jennifer E Yeh
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA; Division of Medical Sciences, Harvard University, Boston, Massachusetts, USA
| | - Roman A Zubarev
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden; Chemical Proteomics, SciLifeLab, Stockholm, Sweden; Department of Pharmacological & Technological Chemistry, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Massimiliano Gaetani
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden; Chemical Proteomics, SciLifeLab, Stockholm, Sweden
| | - Naama Kanarek
- Department of Pathology, Boston Children's Hospital, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; The Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA
| | - Brent D G Page
- Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden; Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada
| | - David A Frank
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA.
| |
Collapse
|
3
|
Machado M, Steinke S, Ganter M. Plasmodium Reproduction, Cell Size, and Transcription: How to Cope With Increasing DNA Content? Front Cell Infect Microbiol 2021; 11:660679. [PMID: 33898332 PMCID: PMC8062723 DOI: 10.3389/fcimb.2021.660679] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/19/2021] [Indexed: 11/13/2022] Open
Abstract
Plasmodium, the unicellular parasite that causes malaria, evolved a highly unusual mode of reproduction. During its complex life cycle, invasive or transmissive stages alternate with proliferating stages, where a single parasite can produce tens of thousands of progeny. In the clinically relevant blood stage of infection, the parasite replicates its genome up to thirty times and forms a multinucleated cell before daughter cells are assembled. Thus, within a single cell cycle, Plasmodium develops from a haploid to a polypoid cell, harboring multiple copies of its genome. Polyploidy creates several biological challenges, such as imbalances in genome output, and cells can respond to this by changing their size and/or alter the production of RNA species and protein to achieve expression homeostasis. However, the effects and possible adaptations of Plasmodium to the massively increasing DNA content are unknown. Here, we revisit and embed current Plasmodium literature in the context of polyploidy and propose potential mechanisms of the parasite to cope with the increasing gene dosage.
Collapse
Affiliation(s)
- Marta Machado
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany.,Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Salome Steinke
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Markus Ganter
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| |
Collapse
|
4
|
Elshemy HA, Zaki MA, Mohamed EI, Khan SI, Lamie PF. A multicomponent reaction to design antimalarial pyridyl-indole derivatives: Synthesis, biological activities and molecular docking. Bioorg Chem 2020; 97:103673. [DOI: 10.1016/j.bioorg.2020.103673] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 01/18/2020] [Accepted: 02/15/2020] [Indexed: 12/21/2022]
|
5
|
Reeve SM, Si D, Krucinska J, Yan Y, Viswanathan K, Wang S, Holt GT, Frenkel MS, Ojewole AA, Estrada A, Agabiti SS, Alverson JB, Gibson ND, Priestley ND, Wiemer AJ, Donald BR, Wright DL. Toward Broad Spectrum Dihydrofolate Reductase Inhibitors Targeting Trimethoprim Resistant Enzymes Identified in Clinical Isolates of Methicillin Resistant Staphylococcus aureus. ACS Infect Dis 2019; 5:1896-1906. [PMID: 31565920 DOI: 10.1021/acsinfecdis.9b00222] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The spread of plasmid borne resistance enzymes in clinical Staphylococcus aureus isolates is rendering trimethoprim and iclaprim, both inhibitors of dihydrofolate reductase (DHFR), ineffective. Continued exploitation of these targets will require compounds that can broadly inhibit these resistance-conferring isoforms. Using a structure-based approach, we have developed a novel class of ionized nonclassical antifolates (INCAs) that capture the molecular interactions that have been exclusive to classical antifolates. These modifications allow for a greatly expanded spectrum of activity across these pathogenic DHFR isoforms, while maintaining the ability to penetrate the bacterial cell wall. Using biochemical, structural, and computational methods, we are able to optimize these inhibitors to the conserved active sites of the endogenous and trimethoprim resistant DHFR enzymes. Here, we report a series of INCA compounds that exhibit low nanomolar enzymatic activity and potent cellular activity with human selectivity against a panel of clinically relevant TMP resistant (TMPR) and methicillin resistant Staphylococcus aureus (MRSA) isolates.
Collapse
Affiliation(s)
- Stephanie M. Reeve
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Road, Storrs, Connecticut 06269, United States
| | - Debjani Si
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Road, Storrs, Connecticut 06269, United States
| | - Jolanta Krucinska
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Road, Storrs, Connecticut 06269, United States
| | - Yongzhao Yan
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Road, Storrs, Connecticut 06269, United States
| | - Kishore Viswanathan
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Road, Storrs, Connecticut 06269, United States
| | - Siyu Wang
- Department of Computer Science, Duke University, 308 Research Drive, Durham, North Carolina 27708, United States
- Program in Computational Biology and Bioinformatics, Duke University, 101 Science Drive, Durham, North Carolina 27708, United States
| | - Graham T. Holt
- Department of Computer Science, Duke University, 308 Research Drive, Durham, North Carolina 27708, United States
- Program in Computational Biology and Bioinformatics, Duke University, 101 Science Drive, Durham, North Carolina 27708, United States
| | - Marcel S. Frenkel
- Department of Biochemistry, Duke University Medical Center, 255 Nanaline H. Duke, Durham, North Carolina 27710, United States
| | - Adegoke A. Ojewole
- Department of Computer Science, Duke University, 308 Research Drive, Durham, North Carolina 27708, United States
- Program in Computational Biology and Bioinformatics, Duke University, 101 Science Drive, Durham, North Carolina 27708, United States
| | - Alexavier Estrada
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Road, Storrs, Connecticut 06269, United States
| | - Sherry S. Agabiti
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Road, Storrs, Connecticut 06269, United States
| | - Jeremy B. Alverson
- Department of Chemistry, University of Montana, 32 Campus Drive, Missoula, Montana 59812, United States
| | - Nathan D. Gibson
- Department of Chemistry, University of Montana, 32 Campus Drive, Missoula, Montana 59812, United States
| | - Nigel D. Priestley
- Department of Chemistry, University of Montana, 32 Campus Drive, Missoula, Montana 59812, United States
| | - Andrew J. Wiemer
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Road, Storrs, Connecticut 06269, United States
| | - Bruce R. Donald
- Department of Computer Science, Duke University, 308 Research Drive, Durham, North Carolina 27708, United States
- Department of Biochemistry, Duke University Medical Center, 255 Nanaline H. Duke, Durham, North Carolina 27710, United States
- Department of Chemistry, Duke University, 124 Science Drive, Durham, North Carolina 27708, United States
| | - Dennis L. Wright
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N. Eagleville Road, Storrs, Connecticut 06269, United States
- Department of Chemistry, University of Connecticut, 55 N. Eagleville Road, Storrs, Connecticut 06269, United States
| |
Collapse
|
6
|
Patel TS, Bhatt JD, Dixit RB, Chudasama CJ, Patel BD, Dixit BC. Design and synthesis of leucine-linked quinazoline-4(3H)-one-sulphonamide molecules distorting malarial reductase activity in the folate pathway. Arch Pharm (Weinheim) 2019; 352:e1900099. [PMID: 31381192 DOI: 10.1002/ardp.201900099] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/28/2019] [Accepted: 06/18/2019] [Indexed: 11/08/2022]
Abstract
Optimization of a modified Grimmel's method for N-heterocyclization of a leucine-linked sulfonamide side-arm at position 2 leading to 2,3-disustituted-4-quinazolin-(3H)-ones was accomplished. Further, 22 hybrid quinazolinone motifs (4a-v) were synthesized by N-heterocyclization reaction under microwave irradiation using the ionic liquid [Bmim][BF4 ]-H2 O as green solvent as well as the catalyst. The in vitro screening of the hybrid entities against the malarial species Plasmodium falciparum yielded five potent molecules 4l, 4n, 4o, 4t, and 4u owning antimalarial activity comparable to those of the reference drugs. In continuation, an in silico study was carried out to obtain a pharmacophoric model and quantitative structure-activity relationship. We also built a 3D-QSAR model to procure more information that could be applied to design new molecules with more potent Pf-DHFR inhibitory activity. The designed pharmacophore was recognized to be more potent for the selected molecules, exhibiting five pharmacophoric features. The active scaffolds were further evaluated for enzyme inhibition efficacy against alleged receptor Pf-DHFR computationally and in vitro, proving their candidature as lead dihydrofolate reductase inhibitors, and the selectivity of the test candidates was ascertained by toxicity study against Vero cells. Good oral bioavailability was also proved by studying pharmacokinetic properties.
Collapse
Affiliation(s)
- Tarosh S Patel
- Chemistry Department, V. P. & R. P. T. P Science College, Affiliated to Sardar Patel University, Vallabh Vidyanagar, Gujarat, India
| | - Jaimin D Bhatt
- Industrial Chemistry Department, V. P. & R. P. T. P Science College, Affiliated to Sardar Patel University, Vallabh Vidyanagar, Gujarat, India
| | - Ritu B Dixit
- Pharmaceutical Chemistry Department, Ashok & Rita Patel Institute of Integrated Studies and Research in Biotechnology and Allied Sciences, New Vallabh Vidyanagar, Gujarat, India
| | - Chaitanya J Chudasama
- Department of Biochemistry, Shree Alpesh N. Patel P. G. Institute, Affiliated to Sardar Patel University, Anand, Gujarat, India
| | - Bhavesh D Patel
- Microbiology Department, V. P. & R. P. T. P Science College, Affiliated to Sardar Patel University, Vallabh Vidyanagar, Gujarat, India
| | - Bharat C Dixit
- Chemistry Department, V. P. & R. P. T. P Science College, Affiliated to Sardar Patel University, Vallabh Vidyanagar, Gujarat, India
| |
Collapse
|
7
|
Patel TS, Bhatt JD, Dixit RB, Chudasama CJ, Patel BD, Dixit BC. Green synthesis, biological evaluation, molecular docking studies and 3D-QSAR analysis of novel phenylalanine linked quinazoline-4(3H)-one-sulphonamide hybrid entities distorting the malarial reductase activity in folate pathway. Bioorg Med Chem 2019; 27:3574-3586. [PMID: 31272837 DOI: 10.1016/j.bmc.2019.06.038] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 06/19/2019] [Accepted: 06/22/2019] [Indexed: 10/26/2022]
Abstract
A modified Grimmel's method for N-heterocyclization of phenylalanine linked sulphonamide side arm at position-2 was optimized leading to 2,3-disustituted-4-quinazolin-(3H)-ones. Further, [Bmim][BF4]-H2O (IL) was used as green solvent as well as catalyst for the synthesis of twenty two hybrid quinazolinone motifs (4a-4v) by N-heterocyclization reaction using microwave irradiation technique. The in vitro screening of the hybrid entities against the malarial species Plasmodium falciparum yielded five potent molecules 4l, 4n, 4r, 4t & 4u owing comparable antimalarial activity to the reference drugs. In continuation, anin silicostudy was carried out to obtain a pharmacophoric model and quantitative structure activity relationship. We also built a 3D-QSAR model to procure more information that could be applied to design new molecules with more potent Pf-DHFR inhibitory activity. The designed pharmacophore was recognized to be more potent for the selected molecules, exhibiting five pharmacophoric features. The active scaffolds were further evaluated for enzyme inhibition efficacy against alleged receptor Pf-DHFR computationally and in vitro, proving their candidature as lead dihydrofolate reductase inhibitors as well as the selectivity of the test candidates was ascertained by toxicity study against vero cells. The perception of good oral bioavailability was also proved by study of pharmacokinetic properties.
Collapse
Affiliation(s)
- Tarosh S Patel
- Chemistry Department, V. P. & R. P. T. P Science College, Affiliated to Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India.
| | - Jaimin D Bhatt
- Industrial Chemistry Department, V. P. & R. P. T. P Science College, Affiliated to Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India
| | - Ritu B Dixit
- Ashok & Rita Patel Institute of Integrated Studies and Research in Biotechnology and Allied Sciences, New Vallabh Vidyanagar, 388121, Gujarat, India
| | - Chaitanya J Chudasama
- Department of Biochemistry, Shree Alpesh N. Patel P. G. Institute, Affiliated to Sardar Patel University, Anand 388001, Gujarat, India
| | - Bhavesh D Patel
- Microbiology Department, V. P. & R. P. T. P Science College, Affiliated to Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India
| | - Bharat C Dixit
- Chemistry Department, V. P. & R. P. T. P Science College, Affiliated to Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India.
| |
Collapse
|
8
|
Hajian B, Scocchera E, Shoen C, Krucinska J, Viswanathan K, G-Dayanandan N, Erlandsen H, Estrada A, Mikušová K, Korduláková J, Cynamon M, Wright D. Drugging the Folate Pathway in Mycobacterium tuberculosis: The Role of Multi-targeting Agents. Cell Chem Biol 2019; 26:781-791.e6. [PMID: 30930162 DOI: 10.1016/j.chembiol.2019.02.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 01/22/2019] [Accepted: 02/24/2019] [Indexed: 01/19/2023]
Abstract
The folate biosynthetic pathway offers many druggable targets that have yet to be exploited in tuberculosis therapy. Herein, we have identified a series of small molecules that interrupt Mycobacterium tuberculosis (Mtb) folate metabolism by dual targeting of dihydrofolate reductase (DHFR), a key enzyme in the folate pathway, and its functional analog, Rv2671. We have also compared the antifolate activity of these compounds with that of para-aminosalicylic acid (PAS). We found that the bioactive metabolite of PAS, in addition to previously reported activity against DHFR, inhibits flavin-dependent thymidylate synthase in Mtb, suggesting a multi-targeted mechanism of action for this drug. Finally, we have shown that antifolate treatment in Mtb decreases the production of mycolic acids, most likely due to perturbation of the activated methyl cycle. We conclude that multi-targeting of the folate pathway in Mtb is associated with highly potent anti-mycobacterial activity.
Collapse
Affiliation(s)
- Behnoush Hajian
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Eric Scocchera
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, USA
| | | | - Jolanta Krucinska
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Kishore Viswanathan
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, USA
| | | | - Heidi Erlandsen
- Center for Open Research Resources and Equipment, University of Connecticut, Storrs, CT 06269, USA
| | - Alexavier Estrada
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Katarína Mikušová
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská Dolina CH-1, Ilkovičova 6, 842 15, Bratislava, Slovakia
| | - Jana Korduláková
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská Dolina CH-1, Ilkovičova 6, 842 15, Bratislava, Slovakia
| | | | - Dennis Wright
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, USA.
| |
Collapse
|
9
|
Ravikumar A, Arzumanyan GA, Obadi MKA, Javanpour AA, Liu CC. Scalable, Continuous Evolution of Genes at Mutation Rates above Genomic Error Thresholds. Cell 2018; 175:1946-1957.e13. [PMID: 30415839 PMCID: PMC6343851 DOI: 10.1016/j.cell.2018.10.021] [Citation(s) in RCA: 146] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 08/16/2018] [Accepted: 10/04/2018] [Indexed: 11/17/2022]
Abstract
Directed evolution is a powerful approach for engineering biomolecules and understanding adaptation. However, experimental strategies for directed evolution are notoriously labor intensive and low throughput, limiting access to demanding functions, multiple functions in parallel, and the study of molecular evolution in replicate. We report OrthoRep, an orthogonal DNA polymerase-plasmid pair in yeast that stably mutates ∼100,000-fold faster than the host genome in vivo, exceeding the error threshold of genomic replication that causes single-generation extinction. User-defined genes in OrthoRep continuously and rapidly evolve through serial passaging, a highly straightforward and scalable process. Using OrthoRep, we evolved drug-resistant malarial dihydrofolate reductases (DHFRs) in 90 independent replicates. We uncovered a more complex fitness landscape than previously realized, including common adaptive trajectories constrained by epistasis, rare outcomes that avoid a frequent early adaptive mutation, and a suboptimal fitness peak that occasionally traps evolving populations. OrthoRep enables a new paradigm of routine, high-throughput evolution of biomolecular and cellular function.
Collapse
Affiliation(s)
- Arjun Ravikumar
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA
| | - Garri A Arzumanyan
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA
| | - Muaeen K A Obadi
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA
| | - Alex A Javanpour
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA
| | - Chang C Liu
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA; Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697, USA.
| |
Collapse
|
10
|
Patel MM, Volkov OA, Leija C, Lemoff A, Phillips MA. A dual regulatory circuit consisting of S-adenosylmethionine decarboxylase protein and its reaction product controls expression of the paralogous activator prozyme in Trypanosoma brucei. PLoS Pathog 2018; 14:e1007404. [PMID: 30365568 PMCID: PMC6221367 DOI: 10.1371/journal.ppat.1007404] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 11/07/2018] [Accepted: 10/12/2018] [Indexed: 01/12/2023] Open
Abstract
Polyamines are essential for cell growth of eukaryotes including the etiologic agent of human African trypanosomiasis (HAT), Trypanosoma brucei. In trypanosomatids, a key enzyme in the polyamine biosynthetic pathway, S-adenosylmethionine decarboxylase (TbAdoMetDC) heterodimerizes with a unique catalytically-dead paralog called prozyme to form the active enzyme complex. In higher eukaryotes, polyamine metabolism is subject to tight feedback regulation by spermidine-dependent mechanisms that are absent in trypanosomatids. Instead, in T. brucei an alternative regulatory strategy based on TbAdoMetDC prozyme has evolved. We previously demonstrated that prozyme protein levels increase in response to loss of TbAdoMetDC activity. Herein, we show that prozyme levels are under translational control by monitoring incorporation of deuterated leucine into nascent prozyme protein. We furthermore identify pathway factors that regulate prozyme mRNA translation. We find evidence for a regulatory feedback mechanism in which TbAdoMetDC protein and decarboxylated AdoMet (dcAdoMet) act as suppressors of prozyme translation. In TbAdoMetDC null cells expressing the human AdoMetDC enzyme, prozyme levels are constitutively upregulated. Wild-type prozyme levels are restored by complementation with either TbAdoMetDC or an active site mutant, suggesting that TbAdoMetDC possesses an enzyme activity-independent function that inhibits prozyme translation. Depletion of dcAdoMet pools by three independent strategies: inhibition/knockdown of TbAdoMetDC, knockdown of AdoMet synthase, or methionine starvation, each cause prozyme upregulation, providing independent evidence that dcAdoMet functions as a metabolic signal for regulation of the polyamine pathway in T. brucei. These findings highlight a potential regulatory paradigm employing enzymes and pseudoenzymes that may have broad implications in biology. Trypanosoma brucei is a single-celled eukaryotic pathogen and the causative agent of human African trypanosomiasis (HAT). Polyamines are organic polycations that are essential for growth in T. brucei to facilitate protein translation and to maintain redox homeostasis. The pathway is the target of eflornithine, a current frontline therapy for treatment of HAT. Polyamine biosynthetic enzymes are regulated at multiple levels in mammals (e.g. transcription, translation and protein turnover), but in contrast, T. brucei lacks these mechanisms. Instead in T. brucei a central enzyme in polyamine metabolism called AdoMetDC must form a complex with a sister protein (termed a pseudoenzyme) to be active. Herein, we show that cellular levels of this sister protein we call prozyme are in turn feedback regulated by both AdoMetDC and by its reaction product in response to cell treatments that reduce pathway output. This regulatory paradigm highlights how pseudoenzymes can evolve to play an important role in metabolic pathway regulation and in organismal fitness.
Collapse
Affiliation(s)
- Manish M. Patel
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Harry Hines Blvd, Dallas, TX, United States of America
| | - Oleg A. Volkov
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Harry Hines Blvd, Dallas, TX, United States of America
| | - Christopher Leija
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Harry Hines Blvd, Dallas, TX, United States of America
| | - Andrew Lemoff
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Harry Hines Blvd, Dallas, TX, United States of America
| | - Margaret A. Phillips
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Harry Hines Blvd, Dallas, TX, United States of America
- * E-mail:
| |
Collapse
|
11
|
Corral MG, Haywood J, Stehl LH, Stubbs KA, Murcha MW, Mylne JS. Targeting plant DIHYDROFOLATE REDUCTASE with antifolates and mechanisms for genetic resistance. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 95:727-742. [PMID: 29876984 DOI: 10.1111/tpj.13983] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 05/16/2018] [Accepted: 05/21/2018] [Indexed: 06/08/2023]
Abstract
The folate biosynthetic pathway and its key enzyme dihydrofolate reductase (DHFR) is a popular target for drug development due to its essential role in the synthesis of DNA precursors and some amino acids. Despite its importance, little is known about plant DHFRs, which, like the enzymes from the malarial parasite Plasmodium, are bifunctional, possessing DHFR and thymidylate synthase (TS) domains. Here using genetic knockout lines we confirmed that either DHFR-TS1 or DHFR-TS2 (but not DHFR-TS3) was essential for seed development. Screening mutated Arabidopsis thaliana seeds for resistance to antimalarial DHFR-inhibitor drugs pyrimethamine and cycloguanil identified causal lesions in DHFR-TS1 and DHFR-TS2, respectively, near the predicted substrate-binding site. The different drug resistance profiles for the plants, enabled by the G137D mutation in DHFR-TS1 and the A71V mutation in DHFR-TS2, were consistent with biochemical studies using recombinant proteins and could be explained by structural models. These findings provide a great improvement in our understanding of plant DHFR-TS and suggest how plant-specific inhibitors might be developed, as DHFR is not currently targeted by commercial herbicides.
Collapse
Affiliation(s)
- Maxime G Corral
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
- The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
| | - Joel Haywood
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
- The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
| | - Luca H Stehl
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
- Faculty of Biology, The University of Freiburg, Schaenzlestrasse 1, Freiburg, 79104, Germany
| | - Keith A Stubbs
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
| | - Monika W Murcha
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
- The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
| | - Joshua S Mylne
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
- The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia
| |
Collapse
|
12
|
Abstract
A critical assessment of new opportunities for drug discovery to treat malaria
Collapse
Affiliation(s)
- John White
- NIH International Center of Excellence for Malaria Research (South Asia), Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Pradipsinh K Rathod
- NIH International Center of Excellence for Malaria Research (South Asia), Department of Chemistry, University of Washington, Seattle, WA, USA.
| |
Collapse
|
13
|
Patel TS, Bhatt JD, Vanparia SF, Patel UH, Dixit RB, Chudasama CJ, Patel BD, Dixit BC. Ionic liquid mediated stereoselective synthesis of alanine linked hybrid quinazoline-4(3H)-one derivatives perturbing the malarial reductase activity in folate pathway. Bioorg Med Chem 2017; 25:6635-6646. [PMID: 29126742 DOI: 10.1016/j.bmc.2017.10.041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/20/2017] [Accepted: 10/30/2017] [Indexed: 11/27/2022]
Abstract
Grimmel's method was optimized as well as modified leading to the cyclization and incorporation of alanine linked sulphonamide in 4-quinazolin-(3H)-ones. Further, the generation of heterocyclic motif at position-3 of 4-quinazolinones was explored by synthesis of imines, which unfortunately led to an isomeric mixture of stereoisomers. The hurdle of diastereomers encountered on the path was eminently rectified by development of new rapid and reproducible methodology involving the use of imidazolium based ionic liquid as solvents as well as catalyst for cyclization as well as synthesis of imines in situ at position-3 leading to procurement of single E-isomer as the target hybrid heterocyclic molecules. The purity and presence of single isomer was also confirmed by HPLC and spectroscopic techniques. Further, the synthesized sulphonamide linked 4-quinazolin-(3H)-ones hybrids were screened for their antimalarial potency rendering potent entities (4b, 4c, 4 l, 4 t and 4u). The active hybrids were progressively screened for enzyme inhibitory efficacy against presumed receptor Pf-DHFR and h-DHFR computationally as well as in vitro, proving their potency as dihydrofolate reductase inhibitors. The ADME properties of these active molecules were also predicted to enhance the knowhow of the oral bioavailability, indicating good bioavailability of the active entities.
Collapse
Affiliation(s)
- Tarosh S Patel
- Chemistry Department, V. P. & R. P. T. P Science College, Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India.
| | - Jaimin D Bhatt
- Chemistry Department, V. P. & R. P. T. P Science College, Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India
| | - Satish F Vanparia
- Chemistry Department, V. P. & R. P. T. P Science College, Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India
| | - Urmila H Patel
- Department of Physics, Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India
| | - Ritu B Dixit
- Ashok & Rita Patel Institute of Integrated Studies and Research in Biotechnology and Allied Sciences, New Vallabh Vidyanagar 388121, Gujarat, India
| | - Chaitanya J Chudasama
- Department of Biochemistry, Shree Alpesh N. Patel P. G. Institute, Sardar Patel University, Anand 388001, Gujarat, India
| | - Bhavesh D Patel
- Microbiology Department, V. P. & R. P. T. P Science College, Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India
| | - Bharat C Dixit
- Chemistry Department, V. P. & R. P. T. P Science College, Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India.
| |
Collapse
|
14
|
Bahia D. A New Trick for a Conserved Enzyme: Mevalonate Kinase, a Glycosomal Enzyme, Can Be Secreted by Trypanosoma cruzi and Modulate Cell Invasion and Signaling. Is It Another Moonlighting Enzyme? Front Cell Infect Microbiol 2017; 7:426. [PMID: 29034216 PMCID: PMC5627032 DOI: 10.3389/fcimb.2017.00426] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 09/15/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Diana Bahia
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.,Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil
| |
Collapse
|
15
|
Knockdown of the Plasmodium falciparum SURFIN4.1 antigen leads to an increase of its cognate transcript. PLoS One 2017; 12:e0183129. [PMID: 28800640 PMCID: PMC5553854 DOI: 10.1371/journal.pone.0183129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 07/31/2017] [Indexed: 11/24/2022] Open
Abstract
The genome of the malaria parasite Plasmodium falciparum contains the surf gene family which encodes large transmembrane proteins of unknown function. While some surf alleles appear to be expressed in sexual stages, others occur in asexual blood stage forms and may be associated to virulence-associated processes and undergo transcriptional switching. We accessed the transcription of surf genes along multiple invasions by real time PCR. Based on the observation of persistent expression of gene surf4.1, we created a parasite line which expresses a conditionally destabilized SURFIN4.1 protein. Upon destabilization of the protein, no interference of parasite growth or morphological changes were detected. However, we observed a strong increase in the transcript quantities of surf4.1 and sometimes of other surf genes in knocked-down parasites. While this effect was reversible when SURFIN4.1 was stabilized again after a few days of destabilization, longer destabilization periods resulted in a transcriptional switch away from surf4.1. When we tested if a longer transcript half-life was responsible for increased transcript detection in SURFIN4.1 knocked-down parasites, no alteration was found compared to control parasite lines. This suggests a specific feedback of the expressed SURFIN protein to its transcript pointing to a novel type of regulation, inedited in Plasmodium.
Collapse
|
16
|
DeMott CM, Majumder S, Burz DS, Reverdatto S, Shekhtman A. Ribosome Mediated Quinary Interactions Modulate In-Cell Protein Activities. Biochemistry 2017; 56:4117-4126. [PMID: 28715177 DOI: 10.1021/acs.biochem.7b00613] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ribosomes are present inside bacterial cells at micromolar concentrations and occupy up to 20% of the cell volume. Under these conditions, even weak quinary interactions between ribosomes and cytosolic proteins can affect protein activity. By using in-cell and in vitro NMR spectroscopy, and biophysical techniques, we show that the enzymes, adenylate kinase and dihydrofolate reductase, and the respective coenzymes, ATP and NADPH, bind to ribosomes with micromolar affinity, and that this interaction suppresses the enzymatic activities of both enzymes. Conversely, thymidylate synthase, which works together with dihydrofolate reductase in the thymidylate synthetic pathway, is activated by ribosomes. We also show that ribosomes impede diffusion of green fluorescent protein in vitro and contribute to the decrease in diffusion in vivo. These results strongly suggest that ribosome-mediated quinary interactions contribute to the differences between in vitro and in vivo protein activities and that ribosomes play a previously under-appreciated nontranslational role in regulating cellular biochemistry.
Collapse
Affiliation(s)
- Christopher M DeMott
- Department of Chemistry, State University of New York at Albany , Albany, New York 12222, United States
| | - Subhabrata Majumder
- Department of Chemistry, State University of New York at Albany , Albany, New York 12222, United States
| | - David S Burz
- Department of Chemistry, State University of New York at Albany , Albany, New York 12222, United States
| | - Sergey Reverdatto
- Department of Chemistry, State University of New York at Albany , Albany, New York 12222, United States
| | - Alexander Shekhtman
- Department of Chemistry, State University of New York at Albany , Albany, New York 12222, United States
| |
Collapse
|
17
|
Clark RL. Animal Embryotoxicity Studies of Key Non-Artemisinin Antimalarials and Use in Women in the First Trimester. Birth Defects Res 2017. [DOI: 10.1002/bdr2.1035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
18
|
Verhoef H, Veenemans J, Mwangi MN, Prentice AM. Safety and benefits of interventions to increase folate status in malaria-endemic areas. Br J Haematol 2017; 177:905-918. [PMID: 28369746 PMCID: PMC5485039 DOI: 10.1111/bjh.14618] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
For decades, folic acid has routinely been given to prevent or treat anaemia in children, pregnant women and people with sickle cell disease. However, there is no conclusive evidence that folate deficiency anaemia constitutes a public health problem in any of these groups. Industrial flour fortification is recommended and implemented in many countries to combat neural tube defects. Dietary folates or folic acid can antagonise the action of antifolate drugs that play a critical role in the prevention and treatment of malaria. Randomised trials have shown that folic acid supplementation increases the rate of treatment failures with sulfadoxine-pyrimethamine. The efficacy of antifolate drugs against Plasmodium is maximized in the absence of exogenous folic acid, suggesting that there is no safe minimum dose of ingested folic acid. We here review the safety and benefits of interventions to increase folate status in malaria-endemic countries. We conclude that formal cost-benefit analyses are required.
Collapse
Affiliation(s)
- Hans Verhoef
- London School of Hygiene and Tropical Medicine, MRC International Nutrition Group, London, UK
- Nutrition Theme, MRC Unit The Gambia, Banjul, Gambia
- Cell Biology and Immunology Group, & Research, Wageningen, The Netherlands
- Division of Human Nutrition, Wageningen University and Research, Wageningen, The Netherlands
| | - Jacobien Veenemans
- Laboratory for Microbiology and Immunology, Admiral de Ruyter Hospital, Goes, The Netherlands
- Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, The Netherlands
| | - Martin N Mwangi
- Division of Human Nutrition, Wageningen University and Research, Wageningen, The Netherlands
| | - Andrew M Prentice
- London School of Hygiene and Tropical Medicine, MRC International Nutrition Group, London, UK
- Nutrition Theme, MRC Unit The Gambia, Banjul, Gambia
| |
Collapse
|
19
|
Vembar SS, Droll D, Scherf A. Translational regulation in blood stages of the malaria parasite Plasmodium spp.: systems-wide studies pave the way. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:772-792. [PMID: 27230797 PMCID: PMC5111744 DOI: 10.1002/wrna.1365] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/21/2016] [Accepted: 04/26/2016] [Indexed: 11/10/2022]
Abstract
The malaria parasite Plasmodium spp. varies the expression profile of its genes depending on the host it resides in and its developmental stage. Virtually all messenger RNA (mRNA) is expressed in a monocistronic manner, with transcriptional activation regulated at the epigenetic level and by specialized transcription factors. Furthermore, recent systems-wide studies have identified distinct mechanisms of post-transcriptional and translational control at various points of the parasite lifecycle. Taken together, it is evident that 'just-in-time' transcription and translation strategies coexist and coordinate protein expression during Plasmodium development, some of which we review here. In particular, we discuss global and specific mechanisms that control protein translation in blood stages of the human malaria parasite Plasmodium falciparum, once a cytoplasmic mRNA has been generated, and its crosstalk with mRNA decay and storage. We also focus on the widespread translational delay observed during the 48-hour blood stage lifecycle of P. falciparum-for over 30% of transcribed genes, including virulence factors required to invade erythrocytes-and its regulation by cis-elements in the mRNA, RNA-processing enzymes and RNA-binding proteins; the first-characterized amongst these are the DNA- and RNA-binding Alba proteins. More generally, we conclude that translational regulation is an emerging research field in malaria parasites and propose that its elucidation will not only shed light on the complex developmental program of this parasite, but may also reveal mechanisms contributing to drug resistance and define new targets for malaria intervention strategies. WIREs RNA 2016, 7:772-792. doi: 10.1002/wrna.1365 For further resources related to this article, please visit the WIREs website.
Collapse
Affiliation(s)
- Shruthi Sridhar Vembar
- Unité Biologie des Interactions Hôte-Parasite, Département de Parasites et Insectes Vecteurs, Institut Pasteur, Paris, France.
| | - Dorothea Droll
- Unité Biologie des Interactions Hôte-Parasite, Département de Parasites et Insectes Vecteurs, Institut Pasteur, Paris, France
| | - Artur Scherf
- Unité Biologie des Interactions Hôte-Parasite, Département de Parasites et Insectes Vecteurs, Institut Pasteur, Paris, France
| |
Collapse
|
20
|
Mudeppa DG, Kumar S, Kokkonda S, White J, Rathod PK. Topoisomerase II from Human Malaria Parasites: EXPRESSION, PURIFICATION, AND SELECTIVE INHIBITION. J Biol Chem 2015; 290:20313-24. [PMID: 26055707 DOI: 10.1074/jbc.m115.639039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Indexed: 11/06/2022] Open
Abstract
Historically, type II topoisomerases have yielded clinically useful drugs for the treatment of bacterial infections and cancer, but the corresponding enzymes from malaria parasites remain understudied. This is due to the general challenges of producing malaria proteins in functional forms in heterologous expression systems. Here, we express full-length Plasmodium falciparum topoisomerase II (PfTopoII) in a wheat germ cell-free transcription-translation system. Functional activity of soluble PfTopoII from the translation lysates was confirmed through both a plasmid relaxation and a DNA decatenation activity that was dependent on magnesium and ATP. To facilitate future drug discovery, a convenient and sensitive fluorescence assay was established to follow DNA decatenation, and a stable, truncated PfTopoII was engineered for high level enzyme production. PfTopoII was purified using a DNA affinity column. Existing TopoII inhibitors previously developed for other non-malaria indications inhibited PfTopoII, as well as malaria parasites in culture at submicromolar concentrations. Even before optimization, inhibitors of bacterial gyrase, GSK299423, ciprofloxacin, and etoposide exhibited 15-, 57-, and 3-fold selectivity for the malarial enzyme over human TopoII. Finally, it was possible to use the purified PfTopoII to dissect the different modes by which these varying classes of TopoII inhibitors could trap partially processed DNA. The present biochemical advancements will allow high throughput chemical screening of compound libraries and lead optimization to develop new lines of antimalarials.
Collapse
Affiliation(s)
- Devaraja G Mudeppa
- From the Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Shiva Kumar
- From the Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Sreekanth Kokkonda
- From the Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - John White
- From the Department of Chemistry, University of Washington, Seattle, Washington 98195
| | - Pradipsinh K Rathod
- From the Department of Chemistry, University of Washington, Seattle, Washington 98195
| |
Collapse
|
21
|
Kumar S, Krishnamoorthy K, Mudeppa DG, Rathod PK. Structure of Plasmodium falciparum orotate phosphoribosyltransferase with autologous inhibitory protein-protein interactions. Acta Crystallogr F Struct Biol Commun 2015; 71:600-8. [PMID: 25945715 PMCID: PMC4427171 DOI: 10.1107/s2053230x1500549x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/17/2015] [Indexed: 11/10/2022] Open
Abstract
The most severe form of malaria is caused by the obligate parasite Plasmodium falciparum. Orotate phosphoribosyltransferase (OPRTase) is the fifth enzyme in the de novo pyrimidine-synthesis pathway in the parasite, which lacks salvage pathways. Among all of the malaria de novo pyrimidine-biosynthesis enzymes, the structure of P. falciparum OPRTase (PfOPRTase) was the only one unavailable until now. PfOPRTase that could be crystallized was obtained after some low-complexity sequences were removed. Four catalytic dimers were seen in the asymmetic unit (a total of eight polypeptides). In addition to revealing unique amino acids in the PfOPRTase active sites, asymmetric dimers in the larger structure pointed to novel parasite-specific protein-protein interactions that occlude the catalytic active sites. The latter could potentially modulate PfOPRTase activity in parasites and possibly provide new insights for blocking PfOPRTase functions.
Collapse
Affiliation(s)
- Shiva Kumar
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | | | | | | |
Collapse
|
22
|
Heinberg A, Kirkman L. The molecular basis of antifolate resistance in Plasmodium falciparum: looking beyond point mutations. Ann N Y Acad Sci 2015; 1342:10-8. [PMID: 25694157 DOI: 10.1111/nyas.12662] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Drugs that target the folate-synthesis pathway have a long history of effectiveness against a variety of pathogens. As antimalarials, the antifolates were safe and well tolerated, but resistance emerged quickly and has persisted even with decreased drug pressure. The primary determinants of resistance in Plasmodium falciparum are well-described point mutations in the enzymes dihydropteroate synthase and dihydrofolate reductase targeted by the combination sulfadoxine-pyrimethamine. Recent work has highlighted the contributions of additional parasite adaptation to antifolate resistance. In fact, the evolution of antifolate-resistant parasites is multifaceted and complex. Gene amplification of the first enzyme in the parasite folate synthesis pathway, GTP-cyclohydrolase, is strongly associated with resistant parasites and potentially contributes to persistence of resistant parasites. Further understanding of how parasites adjust flux through the folate pathway is important to the further development of alternative agents targeting this crucial synthesis pathway.
Collapse
|
23
|
Caro F, Ahyong V, Betegon M, DeRisi JL. Genome-wide regulatory dynamics of translation in the Plasmodium falciparum asexual blood stages. eLife 2014; 3. [PMID: 25493618 PMCID: PMC4371882 DOI: 10.7554/elife.04106] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Accepted: 11/06/2014] [Indexed: 12/11/2022] Open
Abstract
The characterization of the transcriptome and proteome of Plasmodium
falciparum has been a tremendous resource for the understanding of the
molecular physiology of this parasite. However, the translational dynamics that link
steady-state mRNA with protein levels are not well understood. In this study, we
bridge this disconnect by measuring genome-wide translation using ribosome profiling,
through five stages of the P. falciparum blood phase developmental
cycle. Our findings show that transcription and translation are tightly coupled, with
overt translational control occurring for less than 10% of the transcriptome.
Translationally regulated genes are predominantly associated with merozoite egress
functions. We systematically define mRNA 5′ leader sequences, and 3′
UTRs, as well as antisense transcripts, along with ribosome occupancy for each, and
establish that accumulation of ribosomes on 5′ leaders is a common transcript
feature. This work represents the highest resolution and broadest portrait of gene
expression and translation to date for this medically important parasite. DOI:http://dx.doi.org/10.7554/eLife.04106.001 The genome of an organism includes all of the genes or information necessary to
build, maintain, and replicate that organism. However, cells with the same
genome—such as a skin cell and a liver cell from the same person—can
look and behave very differently depending on which of the genes in their genomes
they express, and to what extent. For a gene to be expressed, its DNA is ‘transcribed’ to make an RNA
molecule, which is then ‘translated’ to make a protein. Efforts to
measure the transcription and translation processes in diseased cells, or in the
microorganisms that cause infections, may lead to new treatments and preventative
medicines. Such work is currently ongoing in the global effort to treat and prevent
malaria. Malaria is both preventable and curable, yet over 600,000 people are estimated to die
from this disease each year. The disease is caused by a single-celled parasite called
Plasmodium. Mosquitoes carry the parasites in their salivary
glands, and when a mosquito bites a human, these parasites are injected into the
bloodstream with the mosquito's saliva. Plasmodium parasites then
travel to and infect the liver, before bursting out of this tissue into the
bloodstream. Here, the parasites infect red blood cells and undergo rounds of
replication during which the symptoms of the disease are manifested. It is also
during this bloodstream phase that parasites can develop into forms capable of
infecting another mosquito and continuing the transmission cycle. The genes, RNA molecules, and proteins of the Plasmodium falciparum
parasite—which causes the most serious cases of malaria in humans—have
been cataloged to better understand the biology of this parasite. However, the
processes that control how, and when, an RNA transcript is translated into a protein
are not well understood. Now Caro et al. have uncovered which RNA molecules are being translated, and by how
much, during Plasmodium development within the blood. The
transcription and translation of genes in this parasite were found to be tightly
linked processes; the expression of only a few genes was controlled more by the
translation process than by transcription. These translationally regulated genes were
found mainly to be those that encode proteins involved in the parasite's exit from
the red blood cells and spread throughout the bloodstream. Caro et al. discovered that genetic regulation of the malaria parasite resembles a
preset genetic program, rather than a system that responds to changes and external
signals. As such, these findings suggest that targeting such a genetic program within
Plasmodium and preventing its implementation could prove an
effective strategy to curb the spread of malaria. DOI:http://dx.doi.org/10.7554/eLife.04106.002
Collapse
Affiliation(s)
- Florence Caro
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Vida Ahyong
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Miguel Betegon
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Joseph L DeRisi
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| |
Collapse
|
24
|
Abbat S, Jain V, Bharatam PV. Origins of the specificity of inhibitor P218 toward wild-type and mutantPfDHFR: a molecular dynamics analysis. J Biomol Struct Dyn 2014; 33:1913-28. [DOI: 10.1080/07391102.2014.979231] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
25
|
Molecular characterization of Plasmodium falciparum Bruno/CELF RNA binding proteins. Mol Biochem Parasitol 2014; 198:1-10. [DOI: 10.1016/j.molbiopara.2014.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 10/13/2014] [Accepted: 10/22/2014] [Indexed: 01/04/2023]
|
26
|
Brancucci NMB, Witmer K, Schmid C, Voss TS. A var gene upstream element controls protein synthesis at the level of translation initiation in Plasmodium falciparum. PLoS One 2014; 9:e100183. [PMID: 24937593 PMCID: PMC4061111 DOI: 10.1371/journal.pone.0100183] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 05/23/2014] [Indexed: 01/14/2023] Open
Abstract
Clonally variant protein expression in the malaria parasite Plasmodium falciparum generates phenotypic variability and allows isogenic populations to adapt to environmental changes encountered during blood stage infection. The underlying regulatory mechanisms are best studied for the major virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1). PfEMP1 is encoded by the multicopy var gene family and only a single variant is expressed in individual parasites, a concept known as mutual exclusion or singular gene choice. var gene activation occurs in situ and is achieved through the escape of one locus from epigenetic silencing. Singular gene choice is controlled at the level of transcription initiation and var 5' upstream (ups) sequences harbour regulatory information essential for mutually exclusive transcription as well as for the trans-generational inheritance of the var activity profile. An additional level of control has recently been identified for the var2csa gene, where an mRNA element in the 5' untranslated region (5' UTR) is involved in the reversible inhibition of translation of var2csa transcripts. Here, we extend the knowledge on post-transcriptional var gene regulation to the common upsC type. We identified a 5' UTR sequence that inhibits translation of upsC-derived mRNAs. Importantly, this 5' UTR element efficiently inhibits translation even in the context of a heterologous upstream region. Further, we found var 5' UTRs to be significantly enriched in uAUGs which are known to impair the efficiency of protein translation in other eukaryotes. Our findings suggest that regulation at the post-transcriptional level is a common feature in the control of PfEMP1 expression in P. falciparum.
Collapse
Affiliation(s)
- Nicolas M. B. Brancucci
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Kathrin Witmer
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Christoph Schmid
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Till S. Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- * E-mail:
| |
Collapse
|
27
|
Expression of functional Plasmodium falciparum enzymes using a wheat germ cell-free system. EUKARYOTIC CELL 2013; 12:1653-63. [PMID: 24123271 DOI: 10.1128/ec.00222-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
One decade after the sequencing of the Plasmodium falciparum genome, 95% of malaria proteins in the genome cannot be expressed in traditional cell-based expression systems, and the targets of the best new leads for antimalarial drug discovery are either not known or not available in functional form. For a disease that kills up to 1 million people per year, routine expression of recombinant malaria proteins in functional form is needed both for the discovery of new therapeutics and for identification of targets of new drugs. We tested the general utility of cell-free systems for expressing malaria enzymes. Thirteen test enzyme sequences were reverse amplified from total RNA, cloned into a plant-like expression vector, and subjected to cell-free expression in a wheat germ system. Protein electrophoresis and autoradiography confirmed the synthesis of products of expected molecular masses. In rare problematic cases, truncated products were avoided by using synthetic genes carrying wheat codons. Scaled-up production generated 39 to 354 μg of soluble protein per 10 mg of translation lysate. Compared to rare proteins where cell-based systems do produce functional proteins, the cell-free yields are comparable or better. All 13 test products were enzymatically active, without failure. This general path to produce functional malaria proteins should now allow the community to access new tools, such as biologically active protein arrays, and lead to the discovery of new chemical functions, structures, and inhibitors of previously inaccessible malaria gene products.
Collapse
|
28
|
Then RL. Antimicrobial Dihydrofolate Reductase Inhibitors - Achievements and Future Options: Review. J Chemother 2013; 16:3-12. [PMID: 15077993 DOI: 10.1179/joc.2004.16.1.3] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Despite all progress made in the fight against infections caused by bacteria, fungi, protozoa or viruses, there is a need for more and new active agents. Intensive efforts are currently directed against many new and attractive targets, and are hoped to result in new useful agents. The opportunities offered by some known and validated targets are, however, by far not exhausted. Dihydrofolate reductase (DHFR, EC 1.5.1.3) attracted much attention over several decades, which yielded several useful agents. There are excellent chances for new drugs in this field, and they are thought to increase by limiting the spectrum of activity. Whereas trimethoprim seems to present the optimum which can be achieved for a broad spectrum antibacterial agent, specific agents could probably be designed for well defined groups or specific organisms, such as staphylococci among the bacteria, or for a number of parasites, such as Plasmodium falciparum, the fungus Pneumocystis carinii, and several protozoa, such as Trypanosoma, Toxoplasma, and others. This would even extend to herbicides or specific plant pathogens. Achievements and current efforts directed against new DHFR-inhibitors are reviewed, considering only the most recent literature.
Collapse
Affiliation(s)
- R L Then
- Morphochem AG, Microbiology, CH-4058 Basel, Switzerland.
| |
Collapse
|
29
|
Coleman BI, Ribacke U, Manary M, Bei AK, Winzeler EA, Wirth DF, Duraisingh MT. Nuclear repositioning precedes promoter accessibility and is linked to the switching frequency of a Plasmodium falciparum invasion gene. Cell Host Microbe 2013; 12:739-50. [PMID: 23245319 DOI: 10.1016/j.chom.2012.11.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 07/14/2012] [Accepted: 10/26/2012] [Indexed: 02/07/2023]
Abstract
Variation of surface adhesins, such as the Plasmodium falciparum erythrocyte invasion ligand PfRh4, is critical for virulence and immune evasion in many microbes. While phenotypic switching is linked to transcriptional changes and chromatin function, the determinants of switching frequency remain poorly defined. By expressing a prokaryotic DNA methylase in P. falciparum, we directly assayed accessibility of transcriptionally active and silent chromatin at the PfRh4 locus. Parasites selected for in vivo PfRh4 activation show a reversible increase in promoter accessibility and exhibit perinuclear repositioning of the locus from a silent to a conserved activation domain. Forced activation of a proximal gene results in a similar repositioning of the PfRh4 locus, with a concomitant increase in PfRh4 activation in a subpopulation of parasites and promoter accessibility correlating with actively transcribed loci. Thus, nuclear repositioning is associated with increased P. falciparum switching frequency, while promoter accessibility is tightly linked to clonally active PfRh4 promoters.
Collapse
Affiliation(s)
- Bradley I Coleman
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | | | | | | | | | | | | |
Collapse
|
30
|
Kim DH, Barrett MP. Metabolite-dependent regulation of gene expression in Trypanosoma brucei. Mol Microbiol 2013; 88:841-5. [PMID: 23668674 DOI: 10.1111/mmi.12243] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2013] [Indexed: 12/21/2022]
Abstract
Mechanisms regulating gene expression in trypanosomatid protozoa differ significantly from those in other eukaryotes. Transcription of the genome appears to be more or less constitutive with the polyadenylation and trans-splicing of large polycistronic RNAs producing monocistronic RNAs whose translation may then depend upon information within their 3' untranslated regions (3'UTRs). Various 3'UTR sequences involved in life-cycle stage-dependent differential gene expression have been described. Moreover, several RNA-binding proteins have been implicated in regulating expression of these transcripts through altering either their stability or their ability to interact with ribosomes. In this issue of Molecular Microbiology Xiao et al. report on a regulatory element within the 3'UTR of the transcript that encodes the polyamine pathway regulatory protein called prozyme. It appears that the RNA element controls translation of the prozyme RNA causing expression to be upregulated when levels of decarboxylated S-adenosylmethionine (dcAdoMet) are depleted. Since prozyme activates the enzyme S-adenosylmethionine decarboxylase (AdoMetDC), which is responsible for the production of dcAdoMet, losing this metabolite leads to upregulation of prozyme, activation of AdoMetDC and restoration of optimal levels of dcAdomet. The system thus represents a novel metabolite-sensing regulatory circuit that maintains polyamine homeostasis in these cells.
Collapse
|
31
|
Xiao Y, Nguyen S, Kim SH, Volkov OA, Tu BP, Phillips MA. Product feedback regulation implicated in translational control of the Trypanosoma brucei S-adenosylmethionine decarboxylase regulatory subunit prozyme. Mol Microbiol 2013; 88:846-61. [PMID: 23634831 DOI: 10.1111/mmi.12226] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2013] [Indexed: 12/12/2022]
Abstract
Human African sleeping sickness (HAT) is caused by the parasitic protozoan Trypanosoma brucei. Polyamine biosynthesis is an important drug target in the treatment of HAT. Previously we showed that trypanosomatid S-adenosylmethionine decarboxylase (AdoMetDC), a key enzyme for biosynthesis of the polyamine spermidine, is activated by heterodimer formation with an inactive paralogue termed prozyme. Furthermore, prozyme protein levels were regulated in response to reduced AdoMetDC activity. Herein we show that T. brucei encodes three prozyme transcripts. The 3'UTRs of these transcripts were mapped and chloramphenicol acetyltransferase (CAT) reporter constructs were used to identify a 1.2 kb region that contained a 3'UTR prozyme regulatory element sufficient to upregulate CAT protein levels (but not RNA) upon AdoMetDC inhibition, supporting the hypothesis that prozyme expression is regulated translationally. To gain insight into trans-acting factors, genetic rescue of AdoMetDC RNAi knock-down lines with human AdoMetDC was performed leading to rescue of the cell growth block, and restoration of prozyme protein to wild-type levels. Metabolite analysis showed that prozyme protein levels were inversely proportional to intracellular levels of decarboxylated AdoMet (dcAdoMet). These data suggest that prozyme translation may be regulated by dcAdoMet, a metabolite not previously identified to play a regulatory role.
Collapse
Affiliation(s)
- Yanjing Xiao
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA
| | | | | | | | | | | |
Collapse
|
32
|
Chaianantakul N, Sirawaraporn R, Sirawaraporn W. Insights into the role of the junctional region of Plasmodium falciparum dihydrofolate reductase-thymidylate synthase. Malar J 2013; 12:91. [PMID: 23497065 PMCID: PMC3623654 DOI: 10.1186/1475-2875-12-91] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 03/09/2013] [Indexed: 12/03/2022] Open
Abstract
Background Plasmodium falciparum dihydrofolate reductase-thymidylate synthase (pfDHFR-TS) is a well-defined target of anti-malarial drug, such as pyrimethamine and cycloguanil. Emergence of malaria parasites resistant to these drugs has been shown to be associated with point mutations of the gene coding for the target enzymes. Although the 3D-structure of P. falciparum bifunctional pfDHFR-TS has been reported previously, relatively little is known about the interactions between the pfDHFR and pfTS domains and the roles of the junctional region that links the two domains together. Therefore, a thorough understanding of the interaction of the two domains and the role of the junctional region of this target is important as the knowledge could assist the development of new effective anti-malarial drugs aimed at overcoming drug-resistant malaria. Methods A system was developed to investigate the interaction between pfDHFR and pfTS domains and the role of the junctional region on the activity of the recombinant pfTS. Based on the ability of co-transformed plasmids coding for pfDHFR and pfTS with truncated junctional region to complement the growth of TS-deficient Escherichia coli strain χ2913recA(DE3) on minimum media without thymidine supplementation, active pfTS mutants with minimal length of junctional region were identified. Interactions between active pfDHFR and the pfTS domains were demonstrated by using a bacterial two-hybrid system. Results Using TS-deficient E. coli strain χ2913recA(DE3), the authors have shown for the first time that in P. falciparum a junctional region of at least 44 amino acids or longer was necessary for the pfTS domain to be active for the synthesis of thymidylate for the cells. Truncation of the junctional region of the bifunctional pfDHFR-TS further confirmed the above results, and suggested that a critical length of the junctional peptide of pfDHFR-TS would be essential for the activity of TS to catalyze the synthesis of thymidylate. Conclusion The present study demonstrated the interactions between the pfDHFR and pfTS domains of the bifunctional pfDHFR-TS, and revealed that the junctional region linking the two protein domains is essential for the expression of catalytically active pfTS domain. The findings could be useful since inhibition of the pfDHFR-TS domain-domain interaction could form a basis for the development of new anti-malarial drugs based on targeting the non-active site region of this important enzyme.
Collapse
Affiliation(s)
- Natpasit Chaianantakul
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | | | | |
Collapse
|
33
|
Lindner SE, Mikolajczak SA, Vaughan AM, Moon W, Joyce BR, Sullivan WJ, Kappe SHI. Perturbations of Plasmodium Puf2 expression and RNA-seq of Puf2-deficient sporozoites reveal a critical role in maintaining RNA homeostasis and parasite transmissibility. Cell Microbiol 2013; 15:1266-83. [PMID: 23356439 DOI: 10.1111/cmi.12116] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 01/18/2013] [Accepted: 01/22/2013] [Indexed: 12/30/2022]
Abstract
Malaria's cycle of infection requires parasite transmission between a mosquito vector and a mammalian host. We here demonstrate that the Plasmodium yoelii Pumilio-FBF family member Puf2 allows the sporozoite to remain infectious in the mosquito salivary glands while awaiting transmission. Puf2 mediates this solely through its RNA-binding domain (RBD) likely by stabilizing or hastening the degradation of specific mRNAs. Puf2 traffics to sporozoite cytosolic granules, which are negative for several markers of stress granules and P-bodies, and disappear rapidly after infection of hepatocytes. In contrast to previously described Plasmodium berghei pbpuf2(-) parasites, pypuf2(-) sporozoites have no apparent defect in host infection when tested early in salivary gland residence, but become progressively non-infectious and prematurely transform into EEFs during prolonged salivary gland residence. The premature overexpression of Puf2 in oocysts causes striking deregulation of sporozoite maturation and infectivity while extension of Puf2 expression in liverstages causes no defect, suggesting that the presence of Puf2 alone is not sufficient for its functions. Finally, by conducting the first comparative RNA-seq analysis of Plasmodium sporozoites, we find that Puf2 may play a role in directly or indirectly maintaining the homeostasis of specific transcripts. These findings uncover requirements for maintaining a window of opportunity for the malaria parasite to accommodate the unpredictable moment of transmission from mosquito to mammalian host.
Collapse
Affiliation(s)
- Scott E Lindner
- Seattle Biomedical Research Institute, Seattle, WA 98109, USA
| | | | | | | | | | | | | |
Collapse
|
34
|
Calderón F, Wilson DM, Gamo FJ. Antimalarial drug discovery: recent progress and future directions. PROGRESS IN MEDICINAL CHEMISTRY 2013; 52:97-151. [PMID: 23384667 DOI: 10.1016/b978-0-444-62652-3.00003-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Félix Calderón
- Tres Cantos Medicines Development Campus, Diseases of the Developing World, GlaxoSmithKline, Tres Cantos, Spain
| | | | | |
Collapse
|
35
|
Domínguez JN, Gamboa de Domínguez N, Rodrigues J, Acosta ME, Caraballo N, León C. Synthesis and antimalarial activity of urenyl Bis-chalcone in vitro and in vivo. J Enzyme Inhib Med Chem 2012; 28:1267-73. [DOI: 10.3109/14756366.2012.733383] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- José N. Domínguez
- Laboratorio de Síntesis Orgánica, Facultad de Farmacia, Universidad Central de Venezuela,
Caracas 1051, Venezuela
| | - Neira Gamboa de Domínguez
- Laboratorio de Bioquímica, Facultad de Farmacia, Universidad Central de Venezuela,
Caracas 1051, Venezuela
| | - Juan Rodrigues
- Laboratorio de Bioquímica, Facultad de Farmacia, Universidad Central de Venezuela,
Caracas 1051, Venezuela
| | - María Eugenia Acosta
- Laboratorio de Bioquímica, Facultad de Farmacia, Universidad Central de Venezuela,
Caracas 1051, Venezuela
| | - Noris Caraballo
- Departamento de Biología y Química, Universidad Pedagógica Experimental Libertador, Instituto Pedagógico de Caracas,
Caracas 1020, Venezuela
| | - Caritza León
- Departamento de Biología y Química, Universidad Pedagógica Experimental Libertador, Instituto Pedagógico de Caracas,
Caracas 1020, Venezuela
| |
Collapse
|
36
|
Ludin P, Woodcroft B, Ralph SA, Mäser P. In silico prediction of antimalarial drug target candidates. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2012; 2:191-9. [PMID: 24533280 DOI: 10.1016/j.ijpddr.2012.07.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 06/28/2012] [Accepted: 07/03/2012] [Indexed: 10/28/2022]
Abstract
The need for new antimalarials is persistent due to the emergence of drug resistant parasites. Here we aim to identify new drug targets in Plasmodium falciparum by phylogenomics among the Plasmodium spp. and comparative genomics to Homo sapiens. The proposed target discovery pipeline is largely independent of experimental data and based on the assumption that P. falciparum proteins are likely to be essential if (i) there are no similar proteins in the same proteome and (ii) they are highly conserved across the malaria parasites of mammals. This hypothesis was tested using sequenced Saccharomycetaceae species as a touchstone. Consecutive filters narrowed down the potential target space of P. falciparum to proteins that are likely to be essential, matchless in the human proteome, expressed in the blood stages of the parasite, and amenable to small molecule inhibition. The final set of 40 candidate drug targets was significantly enriched in essential proteins and comprised proven targets (e.g. dihydropteroate synthetase or enzymes of the non-mevalonate pathway), targets currently under investigation (e.g. calcium-dependent protein kinases), and new candidates of potential interest such as phosphomannose isomerase, phosphoenolpyruvate carboxylase, signaling components, and transporters. The targets were prioritized based on druggability indices and on the availability of in vitro assays. Potential inhibitors were inferred from similarity to known targets of other disease systems. The identified candidates from P. falciparum provide insight into biochemical peculiarities and vulnerable points of the malaria parasite and might serve as starting points for rational drug discovery.
Collapse
Affiliation(s)
- Philipp Ludin
- Swiss Tropical and Public Health Institute, 4002 Basel, Switzerland ; University of Basel, 4000 Basel, Switzerland
| | - Ben Woodcroft
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia
| | - Stuart A Ralph
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia
| | - Pascal Mäser
- Swiss Tropical and Public Health Institute, 4002 Basel, Switzerland ; University of Basel, 4000 Basel, Switzerland
| |
Collapse
|
37
|
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
|
38
|
Jordão FM, Kimura EA, Katzin AM. Isoprenoid biosynthesis in the erythrocytic stages of Plasmodium falciparum. Mem Inst Oswaldo Cruz 2012; 106 Suppl 1:134-41. [PMID: 21881768 DOI: 10.1590/s0074-02762011000900018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 06/15/2011] [Indexed: 12/19/2022] Open
Abstract
The development of new drugs is one strategy for malaria control. Biochemical pathways localised in the apicoplast of the parasite, such as the synthesis of isoprenic precursors, are excellent targets because they are different or absent in the human host. Isoprenoids are a large and highly diverse group of natural products with many functions and their synthesis is essential for the parasite's survival. During the last few years, the genes, enzymes, intermediates and mechanisms of this biosynthetic route have been elucidated. In this review, we comment on some aspects of the methylerythritol phosphate pathway and discuss the presence of diverse isoprenic products such as dolichol, ubiquinone, carotenoids, menaquinone and isoprenylated proteins, which are biosynthesised during the intraerythrocytic stages of Plasmodium falciparum.
Collapse
Affiliation(s)
- Fabiana Morandi Jordão
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brasil
| | | | | |
Collapse
|
39
|
Kuroda Y, Isarai K, Murata S. Reductive amination of 6-acetylpteridine to 6-N-arylaminoethylpteridine. HETEROCYCL COMMUN 2012. [DOI: 10.1515/hc-2012-0046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract6-Acetyl-7-methylpteridine derivatives
Collapse
|
40
|
Hayashi H, Tazoe Y, Horino M, Fujimaki-Katoh C, Tsuboi S, Matsuyama T, Kosuge K, Yamada H, Tsuji D, Inoue K, Itoh K. An artifact derived from a pseudogene led to the discovery of microRNA binding site polymorphism in the 3'-untranslated region of the human dihydrofolate reductase gene. Drug Metab Pharmacokinet 2011; 27:263-7. [PMID: 22201119 DOI: 10.2133/dmpk.dmpk-11-nt-092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel single-nucleotide polymorphism (SNP) in the 3'-untranslated region of the human dihydrofolate reductase (DHFR) gene with enhanced expression was identified in 2001. In 2007, it was reported that this SNP, DHFR C829T, was located close to a microRNA binding site and contributed to the stability of mRNA. Many researchers have analyzed this SNP in several races including Asians and Caucasians. However, the mutation allele is not yet confirmed in most populations. In this study, we reinvestigated the frequency of this SNP using three methods. First, this SNP in genomic DNA was analyzed by a PCR-restriction fragment length polymorphism method. Second, this SNP in mRNA was analyzed by a single nucleotide extension method following a reverse transcription reaction. Third, the mRNA expression level was analyzed by a real-time PCR method. The findings in our study, regarding the discovery of this SNP, suggest that the SNP is an artifact caused by contamination by the genomic DNA of the pseudogene DHFRP1. This study is a reinvestigation of a newly discovered genetic polymorphism.
Collapse
Affiliation(s)
- Hideki Hayashi
- Department of Clinical Pharmacology & Genetics, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Prediction of residues involved in inhibitor specificity in the dihydrofolate reductase family. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1870-9. [DOI: 10.1016/j.bbapap.2011.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 07/29/2011] [Accepted: 08/01/2011] [Indexed: 12/11/2022]
|
42
|
Somsak V, Uthaipibull C, Prommana P, Srichairatanakool S, Yuthavong Y, Kamchonwongpaisan S. Transgenic Plasmodium parasites stably expressing Plasmodium vivax dihydrofolate reductase-thymidylate synthase as in vitro and in vivo models for antifolate screening. Malar J 2011; 10:291. [PMID: 21981896 PMCID: PMC3198988 DOI: 10.1186/1475-2875-10-291] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 10/07/2011] [Indexed: 11/12/2022] Open
Abstract
Background Plasmodium vivax is the most prevalent cause of human malaria in tropical regions outside the African continent. The lack of a routine continuous in vitro culture of this parasite makes it difficult to develop specific drugs for this disease. To facilitate the development of anti-P. vivax drugs, bacterial and yeast surrogate models expressing the validated P. vivax target dihydrofolate reductase-thymidylate synthase (DHFR-TS) have been generated; however, they can only be used as primary screening models because of significant differences in enzyme expression level and in vivo drug metabolism between the surrogate models and P. vivax parasites. Methods Plasmodium falciparum and Plasmodium berghei parasites were transfected with DNA constructs bearing P. vivax dhfr-ts pyrimethamine sensitive (wild-type) and pyrimethamine resistant (mutant) alleles. Double crossover homologous recombination was used to replace the endogenous dhfr-ts of P. falciparum and P. berghei parasites with P. vivax homologous genes. The integration of Pvdhfr-ts genes via allelic replacement was verified by Southern analysis and the transgenic parasites lines validated as models by standard drug screening assays. Results Transgenic P. falciparum and P. berghei lines stably expressing PvDHFR-TS replacing the endogenous parasite DHFR-TS were obtained. Anti-malarial drug screening assays showed that transgenic parasites expressing wild-type PvDHFR-TS were pyrimethamine-sensitive, whereas transgenic parasites expressing mutant PvDHFR-TS were pyrimethamine-resistant. The growth and sensitivity to other types of anti-malarial drugs in the transgenic parasites were otherwise indistinguishable from the parental parasites. Conclusion With the permanent integration of Pvdhfr-ts gene in the genome, the transgenic Plasmodium lines expressing PvDHFR-TS are genetically stable and will be useful for screening anti-P. vivax compounds targeting PvDHFR-TS. A similar approach could be used to generate transgenic models specific for other targets of interest, thus facilitating the development of anti-P. vivax drugs in general.
Collapse
Affiliation(s)
- Voravuth Somsak
- Protein-Ligand Engineering and Molecular Biology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Thailand Science Park, Pathumthani 12120, Thailand
| | | | | | | | | | | |
Collapse
|
43
|
Hedstrom L, Liechti G, Goldberg JB, Gollapalli DR. The antibiotic potential of prokaryotic IMP dehydrogenase inhibitors. Curr Med Chem 2011; 18:1909-18. [PMID: 21517780 DOI: 10.2174/092986711795590129] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 04/04/2011] [Indexed: 12/30/2022]
Abstract
Inosine 5'-monophosphate dehydrogenase (IMPDH) catalyzes the first committed step of guanosine 5'-monophosphate (GMP) biosynthesis, and thus regulates the guanine nucleotide pool, which in turn governs proliferation. Human IMPDHs are validated targets for immunosuppressive, antiviral and anticancer drugs, but as yet microbial IMPDHs have not been exploited in antimicrobial chemotherapy. Selective inhibitors of IMPDH from Cryptosporidium parvum have recently been discovered that display anti-parasitic activity in cell culture models of infection. X-ray crystal structure and mutagenesis experiments identified the structural features that determine inhibitor susceptibility. These features are found in IMPDHs from a wide variety of pathogenic bacteria, including select agents and multiply drug resistant strains. A second generation inhibitor displays antibacterial activity against Helicobacter pylori, demonstrating the antibiotic potential of IMPDH inhibitors.
Collapse
Affiliation(s)
- L Hedstrom
- Brandeis University, Departments of Biology, Waltham, MA 02454-9110, USA.
| | | | | | | |
Collapse
|
44
|
Muregi FW, Ohta I, Masato U, Kino H, Ishih A. Resistance of a rodent malaria parasite to a thymidylate synthase inhibitor induces an apoptotic parasite death and imposes a huge cost of fitness. PLoS One 2011; 6:e21251. [PMID: 21698180 PMCID: PMC3116895 DOI: 10.1371/journal.pone.0021251] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 05/25/2011] [Indexed: 01/09/2023] Open
Abstract
Background The greatest impediment to effective malaria control is drug resistance in Plasmodium falciparum, and thus understanding how resistance impacts on the parasite's fitness and pathogenicity may aid in malaria control strategy. Methodology/Principal Findings To generate resistance, P. berghei NK65 was subjected to 5-fluoroorotate (FOA, an inhibitor of thymidylate synthase, TS) pressure in mice. After 15 generations of drug pressure, the 2% DT (the delay time for proliferation of parasites to 2% parasitaemia, relative to untreated wild-type controls) reduced from 8 days to 4, equalling the controls. Drug sensitivity studies confirmed that FOA-resistance was stable. During serial passaging in the absence of drug, resistant parasite maintained low growth rates (parasitaemia, 15.5%±2.9, 7 dpi) relative to the wild-type (45.6%±8.4), translating into resistance cost of fitness of 66.0%. The resistant parasite showed an apoptosis-like death, as confirmed by light and transmission electron microscopy and corroborated by oligonucleosomal DNA fragmentation. Conclusions/Significance The resistant parasite was less fit than the wild-type, which implies that in the absence of drug pressure in the field, the wild-type alleles may expand and allow drugs withdrawn due to resistance to be reintroduced. FOA resistance led to depleted dTTP pools, causing thymineless parasite death via apoptosis. This supports the tenet that unicellular eukaryotes, like metazoans, also undergo apoptosis. This is the first report where resistance to a chemical stimulus and not the stimulus itself is shown to induce apoptosis in a unicellular parasite. This finding is relevant in cancer therapy, since thymineless cell death induced by resistance to TS-inhibitors can further be optimized via inhibition of pyrimidine salvage enzymes, thus providing a synergistic impact. We conclude that since apoptosis is a process that can be pharmacologically modulated, the parasite's apoptotic machinery may be exploited as a novel drug target in malaria and other protozoan diseases of medical importance.
Collapse
Affiliation(s)
- Francis W Muregi
- Department of Infectious Diseases, Hamamatsu University School of Medicine, Hamamatsu, Japan.
| | | | | | | | | |
Collapse
|
45
|
Drug discovery and the use of computational approaches for infectious diseases. Future Med Chem 2011; 3:1011-25. [DOI: 10.4155/fmc.11.60] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
For centuries infectious diseases were the scourge of humanity, overcome only by the discovery of vaccination and penicillin. With an armamentarium of effective antibiotics, vaccines and drugs at hand, infectious diseases for many years were considered to be negligible. With the onset of the AIDS pandemic, the return of tuberculosis and influenza (e.g., swine influenza) this notion has changed in recent years. Drug discovery for infectious diseases, therefore, is again gaining increasing interest. This article discusses the drug-discovery process in this area and introduces major computational approaches used to identify suitable drug targets and to discover and optimize chemical lead compounds towards drug candidates using examples from antiparasitic drug discovery.
Collapse
|
46
|
Bateman KS, Cherney MM, Mahuran DJ, Tropak M, James MNG. Crystal structure of β-hexosaminidase B in complex with pyrimethamine, a potential pharmacological chaperone. J Med Chem 2011; 54:1421-9. [PMID: 21265544 DOI: 10.1021/jm101443u] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
β-Hexosaminidases (β-hex) are a group of glycosyl hydrolase isozymes that break down neutral and sialylated glycosphingolipids in the lysosomes, thereby preventing their buildup in neuronal cells. Some mutants of β-hex have decreased folding stability that results in adult-onset forms of lysosomal storage diseases. However, prevention of the harmful accumulation of glycolipids only requires 10% of wild-type activity. Pyrimethamine (PYR) is a potential pharmacological chaperone that works by stabilizing these mutant enzymes sufficiently to allow more β-hex to arrive in the lysosome, where it can carry out its function. An X-ray structure of the complex between human β-hexosaminidase B (HexB) and PYR has been determined to 2.8 Å. PYR binds to the active site of HexB where several favorable van der Waals contacts and hydrogen bonds are introduced. Small adjustments of the enzyme structure are required to accommodate the ligand, and details of the inhibition and stabilization properties of PYR are discussed.
Collapse
Affiliation(s)
- Katherine S Bateman
- Department of Biochemistry, 4-29 Medical Sciences Building, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | | | | | | | | |
Collapse
|
47
|
Partow S, Siewers V, Bjørn S, Nielsen J, Maury J. Characterization of different promoters for designing a new expression vector in Saccharomyces cerevisiae. Yeast 2010; 27:955-64. [DOI: 10.1002/yea.1806] [Citation(s) in RCA: 237] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
48
|
Hughes KR, Philip N, Lucas Starnes G, Taylor S, Waters AP. From cradle to grave: RNA biology in malaria parasites. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:287-303. [DOI: 10.1002/wrna.30] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Katie R. Hughes
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
| | - Nisha Philip
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
| | - G. Lucas Starnes
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
| | - Sonya Taylor
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
| | - Andrew P. Waters
- Division of Infection and Immunity, Faculty of Biomedical Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland, UK
| |
Collapse
|
49
|
High-throughput genotyping of single nucleotide polymorphisms in the Plasmodium falciparum dhfr gene by asymmetric PCR and melt-curve analysis. J Clin Microbiol 2010; 48:3081-7. [PMID: 20631115 DOI: 10.1128/jcm.00634-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Mutations within the Plasmodium falciparum dihydrofolate reductase gene (Pfdhfr) contribute to resistance to antimalarials such as sulfadoxine-pyrimethamine (SP). Of particular importance are the single nucleotide polymorphisms (SNPs) within codons 51, 59, 108, and 164 in the Pfdhfr gene that are associated with SP treatment failure. Given that traditional genotyping methods are time-consuming and laborious, we developed an assay that provides the rapid, high-throughput analysis of parasite DNA isolated from clinical samples. This assay is based on asymmetric real-time PCR and melt-curve analysis (MCA) performed on the LightCycler platform. Unlabeled probes specific to each SNP are included in the reaction mixture and hybridize differentially to the mutant and wild-type sequences within the amplicon, generating distinct melting curves. Since the probe is present throughout PCR and MCA, the assay proceeds seamlessly with no further addition of reagents. This assay was validated for analytical sensitivity and specificity using plasmids, purified genomic DNA from reference strains, and parasite cultures. For all four SNPs, correct genotypes were identified with 100 copies of the template. The performance of the assay was evaluated with a blind panel of clinical isolates from travelers with low-level parasitemia. The concordance between our assay and DNA sequencing ranged from 84 to 100% depending on the SNP. We also directly compared our MCA assay to a published TaqMan real-time PCR assay and identified major issues with the specificity of the TaqMan probes. Our assay provides a number of technical improvements that facilitate the high-throughput screening of patient samples to identify SP-resistant malaria.
Collapse
|
50
|
Defining the role of mutations in Plasmodium vivax dihydrofolate reductase-thymidylate synthase gene using an episomal Plasmodium falciparum transfection system. Antimicrob Agents Chemother 2010; 54:3927-32. [PMID: 20566761 DOI: 10.1128/aac.00628-10] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium vivax resistance to antifolates is prevalent throughout Australasia and is caused by point mutations within the parasite dihydrofolate reductase (DHFR)-thymidylate synthase. Several unique mutations have been reported in P. vivax DHFR, and their roles in resistance to classic and novel antifolates are not entirely clear due, in part, to the inability to culture P. vivax in vitro. In this study, we use a homologous system to episomally express both wild-type and various mutant P. vivax dhfr (pvdhfr) alleles in an antifolate-sensitive line of P. falciparum and to assess their influences on the susceptibility of the recipient P. falciparum line to commonly used and new antifolate drugs. Although the wild-type pvdhfr-transfected P. falciparum line was as susceptible to antifolate drugs as the P. falciparum parent line, the single (117N), double (57L/117T and 58R/117T), and quadruple (57L/58R/61M/117T) mutant pvdhfr alleles conferred a marked reduction in their susceptibilities to antifolates. The resistance index increased with the number of mutations in these alleles, indicating that these mutations contribute to antifolate resistance directly. In contrast, the triple mutant allele (58R/61M/117T) significantly reversed the resistance to all antifolates, indicating that 61M may be a compensatory mutation. These findings help elucidate the mechanism of antifolate resistance and the effect of existing mutations in the parasite population on the current and new generation of antifolate drugs. It also demonstrates that the episomal transfection system has the potential to provide a rapid screening system for drug development and for studying drug resistance mechanisms in P. vivax.
Collapse
|