1
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Keroack CD, Elsworth B, Tennessen JA, Paul AS, Hua R, Ramirez-Ramirez L, Ye S, Moreira CK, Meyers MJ, Zarringhalam K, Duraisingh MT. Comparative chemical genomics in Babesia species identifies the alkaline phosphatase PhoD as a determinant of antiparasitic resistance. Proc Natl Acad Sci U S A 2024; 121:e2312987121. [PMID: 38377214 PMCID: PMC10907312 DOI: 10.1073/pnas.2312987121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 01/09/2024] [Indexed: 02/22/2024] Open
Abstract
Babesiosis is an emerging zoonosis and widely distributed veterinary infection caused by 100+ species of Babesia parasites. The diversity of Babesia parasites and the lack of specific drugs necessitate the discovery of broadly effective antibabesials. Here, we describe a comparative chemogenomics (CCG) pipeline for the identification of conserved targets. CCG relies on parallel in vitro evolution of resistance in independent populations of Babesia spp. (B. bovis and B. divergens). We identified a potent antibabesial, MMV019266, from the Malaria Box, and selected for resistance in two species of Babesia. After sequencing of multiple independently derived lines in the two species, we identified mutations in a membrane-bound metallodependent phosphatase (phoD). In both species, the mutations were found in the phoD-like phosphatase domain. Using reverse genetics, we validated that mutations in bdphoD confer resistance to MMV019266 in B. divergens. We have also demonstrated that BdPhoD localizes to the endomembrane system and partially with the apicoplast. Finally, conditional knockdown and constitutive overexpression of BdPhoD alter the sensitivity to MMV019266 in the parasite. Overexpression of BdPhoD results in increased sensitivity to the compound, while knockdown increases resistance, suggesting BdPhoD is a pro-susceptibility factor. Together, we have generated a robust pipeline for identification of resistance loci and identified BdPhoD as a resistance mechanism in Babesia species.
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Affiliation(s)
- Caroline D. Keroack
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Brendan Elsworth
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Jacob A. Tennessen
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Aditya S. Paul
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Renee Hua
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Luz Ramirez-Ramirez
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Sida Ye
- Department of Mathematics, University of Massachusetts, Boston, MA02125
- Center for Personalized Cancer Therapy, University of Massachusetts, Boston, MA02125
| | - Cristina K. Moreira
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
| | - Marvin J. Meyers
- Department of Chemistry, Saint Louis University, St. Louis, MO63103
| | - Kourosh Zarringhalam
- Department of Mathematics, University of Massachusetts, Boston, MA02125
- Center for Personalized Cancer Therapy, University of Massachusetts, Boston, MA02125
| | - Manoj T. Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA02115
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2
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dos Santos DA, Souza HFS, Silber AM, de Souza TDACB, Ávila AR. Protein kinases on carbon metabolism: potential targets for alternative chemotherapies against toxoplasmosis. Front Cell Infect Microbiol 2023; 13:1175409. [PMID: 37287468 PMCID: PMC10242022 DOI: 10.3389/fcimb.2023.1175409] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/02/2023] [Indexed: 06/09/2023] Open
Abstract
The apicomplexan parasite Toxoplasma gondii is the causative agent of toxoplasmosis, a global disease that significantly impacts human health. The clinical manifestations are mainly observed in immunocompromised patients, including ocular damage and neuronal alterations leading to psychiatric disorders. The congenital infection leads to miscarriage or severe alterations in the development of newborns. The conventional treatment is limited to the acute phase of illness, without effects in latent parasites; consequently, a cure is not available yet. Furthermore, considerable toxic effects and long-term therapy contribute to high treatment abandonment rates. The investigation of exclusive parasite pathways would provide new drug targets for more effective therapies, eliminating or reducing the side effects of conventional pharmacological approaches. Protein kinases (PKs) have emerged as promising targets for developing specific inhibitors with high selectivity and efficiency against diseases. Studies in T. gondii have indicated the presence of exclusive PKs without homologs in human cells, which could become important targets for developing new drugs. Knockout of specific kinases linked to energy metabolism have shown to impair the parasite development, reinforcing the essentiality of these enzymes in parasite metabolism. In addition, the specificities found in the PKs that regulate the energy metabolism in this parasite could bring new perspectives for safer and more efficient therapies for treating toxoplasmosis. Therefore, this review provides an overview of the limitations for reaching an efficient treatment and explores the role of PKs in regulating carbon metabolism in Toxoplasma, discussing their potential as targets for more applied and efficient pharmacological approaches.
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Affiliation(s)
| | - Higo Fernando Santos Souza
- Laboratory of Biochemistry of Trypanosomes (LabTryp), Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Ariel M. Silber
- Laboratory of Biochemistry of Trypanosomes (LabTryp), Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | | | - Andréa Rodrigues Ávila
- Laboratório de Pesquisa em Apicomplexa, Instituto Carlos Chagas, Fiocruz, Curitiba, Brazil
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3
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Elahi R, Prigge ST. New insights into apicoplast metabolism in blood-stage malaria parasites. Curr Opin Microbiol 2023; 71:102255. [PMID: 36563485 PMCID: PMC9852000 DOI: 10.1016/j.mib.2022.102255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 12/24/2022]
Abstract
The apicoplast of Plasmodium falciparum is the only source of essential isoprenoid precursors and Coenzyme A (CoA) in the parasite. Isoprenoid precursor synthesis relies on the iron-sulfur cluster (FeS) cofactors produced within the apicoplast, rendering FeS synthesis an essential function of this organelle. Recent reports provide important insights into the roles of FeS cofactors and the use of isoprenoid precursors and CoA both inside and outside the apicoplast. Here, we review the recent insights into the roles of these metabolites in blood-stage malaria parasites and discuss new questions that have been raised in light of these discoveries.
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Affiliation(s)
- Rubayet Elahi
- Department of Molecular Microbiology and Immunology, Johns Hopkins University, Baltimore, MD, USA; The Johns Hopkins Malaria Research Institute, Baltimore, MD, USA
| | - Sean T Prigge
- Department of Molecular Microbiology and Immunology, Johns Hopkins University, Baltimore, MD, USA; The Johns Hopkins Malaria Research Institute, Baltimore, MD, USA.
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4
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Morehouse JP, Baker TA, Sauer RT. FtsH degrades dihydrofolate reductase by recognizing a partially folded species. Protein Sci 2022; 31:e4410. [PMID: 36630366 PMCID: PMC9601784 DOI: 10.1002/pro.4410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 07/21/2022] [Accepted: 07/24/2022] [Indexed: 01/14/2023]
Abstract
AAA+ proteolytic machines play essential roles in maintaining and rebalancing the cellular proteome in response to stress, developmental cues, and environmental changes. Of the five AAA+ proteases in Escherichia coli, FtsH is unique in its attachment to the inner membrane and its function in degrading both membrane and cytosolic proteins. E. coli dihydrofolate reductase (DHFR) is a stable and biophysically well-characterized protein, which a previous study found resisted FtsH degradation despite the presence of an ssrA degron. By contrast, we find that FtsH degrades DHFR fused to a long peptide linker and ssrA tag. Surprisingly, we also find that FtsH degrades DHFR with shorter linkers and ssrA tag, and without any linker or tag. Thus, FtsH must be able to recognize a sequence element or elements within DHFR. We find that FtsH degradation of DHFR is noncanonical in the sense that it does not rely upon recognition of an unstructured polypeptide at or near the N-terminus or C-terminus of the substrate. Results using peptide-array experiments, mutant DHFR proteins, and fusion proteins suggest that FtsH recognizes an internal sequence in a species of DHFR that is partially unfolded. Overall, our findings provide insight into substrate recognition by FtsH and indicate that its degradation capacity is broader than previously reported.
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Affiliation(s)
- Juhee P. Morehouse
- Department of BiologyMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | - Tania A. Baker
- Department of BiologyMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | - Robert T. Sauer
- Department of BiologyMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
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5
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Bernard MM, Mohanty A, Rajendran V. Title: A Comprehensive Review on Classifying Fast-acting and Slow-acting Antimalarial Agents Based on Time of Action and Target Organelle of Plasmodium sp. Pathog Dis 2022; 80:6589403. [PMID: 35588061 DOI: 10.1093/femspd/ftac015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/20/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
The clinical resistance towards malarial parasites has rendered many antimalarials ineffective, likely due to a lack of understanding of time of action and stage specificity of all life stages. Therefore, to tackle this problem a more incisive comprehensive analysis of the fast and slow-acting profile of antimalarial agents relating to parasite time-kill kinetics and the target organelle on the progression of blood-stage parasites was carried out. It is evident from numerous findings that drugs targeting food vacuole, nuclear components, and endoplasmic reticulum mainly exhibit a fast-killing phenotype within 24h affecting first-cycle activity. Whereas drugs targeting mitochondria, apicoplast, microtubules, parasite invasion and egress exhibit a largely slow-killing phenotype within 96-120h, affecting second-cycle activity with few exemptions as moderately fast-killing. It is essential to understand the susceptibility of drugs on rings, trophozoites, schizonts, merozoites, and the appearance of organelle at each stage of 48h intraerythrocytic parasite cycle. Therefore, these parameters may facilitate the paradigm for understanding the timing of antimalarials action in deciphering its precise mechanism linked with time. Thus, classifying drugs based on the time of killing may promote designing new combination regimens against varied strains of P. falciparum and evaluating potential clinical resistance.
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Affiliation(s)
- Monika Marie Bernard
- Department of Microbiology, School of Life Sciences, Pondicherry University, Puducherry 605014, India
| | - Abhinab Mohanty
- Department of Microbiology, School of Life Sciences, Pondicherry University, Puducherry 605014, India
| | - Vinoth Rajendran
- Department of Microbiology, School of Life Sciences, Pondicherry University, Puducherry 605014, India
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6
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Elaagip A, Absalon S, Florentin A. Apicoplast Dynamics During Plasmodium Cell Cycle. Front Cell Infect Microbiol 2022; 12:864819. [PMID: 35573785 PMCID: PMC9100674 DOI: 10.3389/fcimb.2022.864819] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/11/2022] [Indexed: 11/21/2022] Open
Abstract
The deadly malaria parasite, Plasmodium falciparum, contains a unique subcellular organelle termed the apicoplast, which is a clinically-proven antimalarial drug target. The apicoplast is a plastid with essential metabolic functions that evolved via secondary endosymbiosis. As an ancient endosymbiont, the apicoplast retained its own genome and it must be inherited by daughter cells during cell division. During the asexual replication of P. falciparum inside human red blood cells, both the parasite, and the apicoplast inside it, undergo massive morphological changes, including DNA replication and division. The apicoplast is an integral part of the cell and thus its development is tightly synchronized with the cell cycle. At the same time, certain aspects of its dynamics are independent of nuclear division, representing a degree of autonomy in organelle biogenesis. Here, we review the different aspects of organelle dynamics during P. falciparum intraerythrocytic replication, summarize our current understanding of these processes, and describe the many open questions in this area of parasite basic cell biology.
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Affiliation(s)
- Arwa Elaagip
- Department of Parasitology and Medical Entomology, Faculty of Medical Laboratory Sciences, University of Khartoum, Khartoum, Sudan
| | - Sabrina Absalon
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States
- *Correspondence: Sabrina Absalon, ; Anat Florentin,
| | - Anat Florentin
- The Kuvin Center for the Study of Infectious and Tropical Diseases, Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
- *Correspondence: Sabrina Absalon, ; Anat Florentin,
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7
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Kobakhidze G, Sethi A, Valimehr S, Ralph SA, Rouiller I. The AAA+ ATPase p97 as a novel parasite and tuberculosis drug target. Trends Parasitol 2022; 38:572-590. [DOI: 10.1016/j.pt.2022.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
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8
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Okada M, Rajaram K, Swift RP, Mixon A, Maschek JA, Prigge ST, Sigala PA. Critical role for isoprenoids in apicoplast biogenesis by malaria parasites. eLife 2022; 11:73208. [PMID: 35257658 PMCID: PMC8959605 DOI: 10.7554/elife.73208] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 03/04/2022] [Indexed: 11/13/2022] Open
Abstract
Isopentenyl pyrophosphate (IPP) is an essential metabolic output of the apicoplast organelle in Plasmodium falciparum malaria parasites and is required for prenylation-dependent vesicular trafficking and other cellular processes. We have elucidated a critical and previously uncharacterized role for IPP in apicoplast biogenesis. Inhibiting IPP synthesis blocks apicoplast elongation and inheritance by daughter merozoites, and apicoplast biogenesis is rescued by exogenous IPP and polyprenols. Knockout of the only known isoprenoid-dependent apicoplast pathway, tRNA prenylation by MiaA, has no effect on blood-stage parasites and thus cannot explain apicoplast reliance on IPP. However, we have localized an annotated polyprenyl synthase (PPS) to the apicoplast. PPS knockdown is lethal to parasites, rescued by IPP and long- (C50) but not short-chain (≤C20) prenyl alcohols, and blocks apicoplast biogenesis, thus explaining apicoplast dependence on isoprenoid synthesis. We hypothesize that PPS synthesizes long-chain polyprenols critical for apicoplast membrane fluidity and biogenesis. This work critically expands the paradigm for isoprenoid utilization in malaria parasites and identifies a novel essential branch of apicoplast metabolism suitable for therapeutic targeting.
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Affiliation(s)
- Megan Okada
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Krithika Rajaram
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, United States
| | - Russell P Swift
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, United States
| | - Amanda Mixon
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - John Alan Maschek
- Metabolomics Core, University of Utah, Salt Lake City, United States
| | - Sean T Prigge
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, United States
| | - Paul A Sigala
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
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9
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Cárdenas P, Esherick LY, Chambonnier G, Dey S, Turlo CV, Nasamu AS, Niles JC. GeneTargeter: Automated In Silico Design for Genome Editing in the Malaria Parasite, Plasmodium falciparum. CRISPR J 2022; 5:155-164. [PMID: 35191751 PMCID: PMC8892962 DOI: 10.1089/crispr.2021.0069] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Functional characterization of the multitude of poorly described proteins in the human malarial pathogen, Plasmodium falciparum, requires tools to enable genome-scale perturbation studies. Here, we present GeneTargeter (genetargeter.mit.edu), a software tool for automating the design of homology-directed repair donor vectors to achieve gene knockouts, conditional knockdowns, and epitope tagging of P. falciparum genes. We demonstrate GeneTargeter-facilitated genome-scale design of six different types of knockout and conditional knockdown constructs for the P. falciparum genome and validate the computational design process experimentally with successful donor vector assembly and transfection. The software's modular nature accommodates arbitrary destination vectors and allows customizable designs that extend the genome manipulation outcomes attainable in Plasmodium and other organisms.
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Affiliation(s)
- Pablo Cárdenas
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lisl Y. Esherick
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Gaël Chambonnier
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Sumanta Dey
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Christopher V. Turlo
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Armiyaw Sebastian Nasamu
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jacquin C. Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.,Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA.,Address correspondence to: Jacquin C. Niles, MD, PhD, Department of Biological Engineering, Massachusetts Institute of Technology, Room 56-341, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA,
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10
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Abstract
Malaria, caused by infection with Plasmodium parasites, remains a significant global health concern. For decades, genetic intractability and limited tools hindered our ability to study essential proteins and pathways in Plasmodium falciparum, the parasite associated with the most severe malaria cases. However, recent years have seen major leaps forward in the ability to genetically manipulate P. falciparum parasites and conditionally control protein expression/function. The conditional knockdown systems used in P. falciparum target all 3 components of the central dogma, allowing researchers to conditionally control gene expression, translation, and protein function. Here, we review some of the common knockdown systems that have been adapted or developed for use in P. falciparum. Much of the work done using conditional knockdown approaches has been performed in asexual, blood-stage parasites, but we also highlight their uses in other parts of the life cycle and discuss new ways of applying these systems outside of the intraerythrocytic stages. With the use of these tools, the field’s understanding of parasite biology is ever increasing, and promising new pathways for antimalarial drug development are being discovered.
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11
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Nasamu AS, Falla A, Pasaje CFA, Wall BA, Wagner JC, Ganesan SM, Goldfless SJ, Niles JC. An integrated platform for genome engineering and gene expression perturbation in Plasmodium falciparum. Sci Rep 2021; 11:342. [PMID: 33431920 PMCID: PMC7801740 DOI: 10.1038/s41598-020-77644-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 11/13/2020] [Indexed: 11/24/2022] Open
Abstract
Establishing robust genome engineering methods in the malarial parasite, Plasmodium falciparum, has the potential to substantially improve the efficiency with which we gain understanding of this pathogen's biology to propel treatment and elimination efforts. Methods for manipulating gene expression and engineering the P. falciparum genome have been validated. However, a significant barrier to fully leveraging these advances is the difficulty associated with assembling the extremely high AT content DNA constructs required for modifying the P. falciparum genome. These are frequently unstable in commonly-used circular plasmids. We address this bottleneck by devising a DNA assembly framework leveraging the improved reliability with which large AT-rich regions can be efficiently manipulated in linear plasmids. This framework integrates several key functional genetics outcomes via CRISPR/Cas9 and other methods from a common, validated framework. Overall, this molecular toolkit enables P. falciparum genetics broadly and facilitates deeper interrogation of parasite genes involved in diverse biological processes.
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Affiliation(s)
- Armiyaw S Nasamu
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 56-341B, Cambridge, MA, 02139, USA
| | - Alejandra Falla
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 56-341B, Cambridge, MA, 02139, USA
| | - Charisse Flerida A Pasaje
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 56-341B, Cambridge, MA, 02139, USA
| | - Bridget A Wall
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 56-341B, Cambridge, MA, 02139, USA
| | - Jeffrey C Wagner
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 56-341B, Cambridge, MA, 02139, USA
| | - Suresh M Ganesan
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 56-341B, Cambridge, MA, 02139, USA
| | - Stephen J Goldfless
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 56-341B, Cambridge, MA, 02139, USA
| | - Jacquin C Niles
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 56-341B, Cambridge, MA, 02139, USA.
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12
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Oberstaller J, Otto TD, Rayner JC, Adams JH. Essential Genes of the Parasitic Apicomplexa. Trends Parasitol 2021; 37:304-316. [PMID: 33419671 DOI: 10.1016/j.pt.2020.11.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 11/11/2020] [Accepted: 11/16/2020] [Indexed: 12/29/2022]
Abstract
Genome-scale mutagenesis screens for genes essential for apicomplexan parasite survival have been completed in three species: Plasmodium falciparum, the major human malaria parasite, Plasmodium berghei, a model rodent malaria parasite, and the more distantly related Toxoplasma gondii, the causative agent of toxoplasmosis. These three species share 2606 single-copy orthologs, 1500 of which have essentiality data in all three screens. In this review, we explore the overlap between these datasets to define the core essential genes of the phylum Apicomplexa. We further discuss the implications of these groundbreaking studies for understanding apicomplexan parasite biology, and we identify promising areas of focus for developing new pan-apicomplexan parasite interventions.
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Affiliation(s)
- Jenna Oberstaller
- Center for Global Health and Infectious Diseases and USF Genomics Program, College of Public Health, University of South Florida, 3720 Spectrum Boulevard, Suite 404, Tampa, FL 33612, USA
| | - Thomas D Otto
- Centre of Immunobiology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Julian C Rayner
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, The Keith Peters Building, Hills Road, Cambridge, Cambridgeshire, CB2 0XY, UK
| | - John H Adams
- Center for Global Health and Infectious Diseases and USF Genomics Program, College of Public Health, University of South Florida, 3720 Spectrum Boulevard, Suite 404, Tampa, FL 33612, USA.
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13
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Butler JH, Baptista RP, Valenciano AL, Zhou B, Kissinger JC, Tumwebaze PK, Rosenthal PJ, Cooper RA, Yue JM, Cassera MB. Resistance to Some But Not Other Dimeric Lindenane Sesquiterpenoid Esters Is Mediated by Mutations in a Plasmodium falciparum Esterase. ACS Infect Dis 2020; 6:2994-3003. [PMID: 32970404 PMCID: PMC11075783 DOI: 10.1021/acsinfecdis.0c00487] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Unique lindenane sesquiterpenoid dimers from Chloranthecae spp. were recently identified with promising in vitro antiplasmodial activity and potentially novel mechanisms of action. To gain mechanistic insights to this new class of natural products, in vitro selection of Plasmodium falciparum resistance to the most active antiplasmodial compound, chlorajaponilide C, was explored. In all selected resistant clones, the half-maximal effective concentration (EC50) of chlorajaponilide C increased >250-fold, and whole genome sequencing revealed mutations in the recently discovered P. falciparum prodrug activation and resistance esterase (PfPARE). Chlorajaponilide C was highly potent (mean EC50 = 1.6 nM, n = 34) against fresh Ugandan P. falciparum isolates. The analysis of the structure-resistance relationships revealed that in vitro potency of a subset of lindenane sesquiterpenoid dimers was not mediated by PfPARE mutations. Thus, chlorajaponilide C, but not some related compounds, required parasite esterase activity for in vitro potency, and those compounds serve as the foundation for development of potent and selective antimalarials.
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Affiliation(s)
- Joshua H Butler
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United States
- Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia 30602, United States
| | - Rodrigo P Baptista
- Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia 30602, United States
| | - Ana L Valenciano
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United States
- Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia 30602, United States
| | - Bin Zhou
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100864, People's Republic of China
| | - Jessica C Kissinger
- Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia 30602, United States
| | | | - Philip J Rosenthal
- Department of Medicine, University of California, San Francisco, California 94110, United States
| | - Roland A Cooper
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, California 94901, United States
| | - Jian-Min Yue
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100864, People's Republic of China
| | - Maria B Cassera
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United States
- Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, Georgia 30602, United States
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14
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Okada M, Guo P, Nalder SA, Sigala PA. Doxycycline has distinct apicoplast-specific mechanisms of antimalarial activity. eLife 2020; 9:60246. [PMID: 33135634 PMCID: PMC7669263 DOI: 10.7554/elife.60246] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 11/01/2020] [Indexed: 12/02/2022] Open
Abstract
Doxycycline (DOX) is a key antimalarial drug thought to kill Plasmodium parasites by blocking protein translation in the essential apicoplast organelle. Clinical use is primarily limited to prophylaxis due to delayed second-cycle parasite death at 1–3 µM serum concentrations. DOX concentrations > 5 µM kill parasites with first-cycle activity but are thought to involve off-target mechanisms outside the apicoplast. We report that 10 µM DOX blocks apicoplast biogenesis in the first cycle and is rescued by isopentenyl pyrophosphate, an essential apicoplast product, confirming an apicoplast-specific mechanism. Exogenous iron rescues parasites and apicoplast biogenesis from first- but not second-cycle effects of 10 µM DOX, revealing that first-cycle activity involves a metal-dependent mechanism distinct from the delayed-death mechanism. These results critically expand the paradigm for understanding the fundamental antiparasitic mechanisms of DOX and suggest repurposing DOX as a faster acting antimalarial at higher dosing whose multiple mechanisms would be expected to limit parasite resistance.
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Affiliation(s)
- Megan Okada
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Ping Guo
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Shai-Anne Nalder
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Paul A Sigala
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
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15
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CaaX-Like Protease of Cyanobacterial Origin Is Required for Complex Plastid Biogenesis in Malaria Parasites. mBio 2020; 11:mBio.01492-20. [PMID: 33024034 PMCID: PMC7542359 DOI: 10.1128/mbio.01492-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Plasmodium parasites, which cause malaria, and related apicomplexans are important human and veterinary pathogens. These parasites represent a highly divergent and understudied branch of eukaryotes, and as such often defy the expectations set by model organisms. One striking example of unique apicomplexan biology is the apicoplast, an essential but nonphotosynthetic plastid derived from an unusual secondary (eukaryote-eukaryote) endosymbiosis. Endosymbioses are a major driver of cellular innovation, and apicoplast biogenesis pathways represent a hot spot for molecular evolution. We previously conducted an unbiased screen for apicoplast biogenesis genes in P. falciparum to uncover these essential and innovative pathways. Here, we validate a novel gene candidate from our screen and show that its role in apicoplast biogenesis does not match its functional annotation predicted by model eukaryotes. Our findings suggest that an uncharacterized chloroplast maintenance pathway has been reused for complex plastid biogenesis in this divergent branch of pathogens. Plasmodium parasites and related apicomplexans contain an essential “complex plastid” organelle of secondary endosymbiotic origin, the apicoplast. Biogenesis of this complex plastid poses a unique challenge requiring evolution of new cellular machinery. We previously conducted a mutagenesis screen for essential apicoplast biogenesis genes to discover organellar pathways with evolutionary and biomedical significance. Here we validate and characterize a gene candidate from our screen, Pf3D7_0913500. Using a conditional knockdown strain, we show that Pf3D7_0913500 depletion causes growth inhibition that is rescued by the sole essential product of the apicoplast, isopentenyl pyrophosphate (IPP), and results in apicoplast loss. Because Pf3D7_0913500 had no previous functional annotation, we name it apicoplast-minus IPP-rescued 4 (AMR4). AMR4 has an annotated CaaX protease and bacteriocin processing (CPBP) domain, which in eukaryotes typically indicates a role in CaaX postprenylation processing. Indeed, AMR4 is the only putative CaaX-like protease in Plasmodium parasites which are known to require protein prenylation, and we confirm that the conserved catalytic residue of AMR4 (E352) is required for its apicoplast function. However, we unexpectedly find that AMR4 does not act in a CaaX postprenylation processing pathway in Plasmodium falciparum. Instead, we find that AMR4 is imported into the apicoplast and is derived from a cyanobacterial CPBP gene which was retained through both primary and secondary endosymbiosis. Our findings suggest that AMR4 is not a true CaaX protease, but instead it performs a conserved, uncharacterized chloroplast function that has been retained for complex plastid biogenesis.
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16
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Abstract
Malaria elimination efforts have been repeatedly hindered by the evolution and spread of multidrug-resistant strains of Plasmodium falciparum. The absence of a commercially available vaccine emphasizes the need for a better understanding of Plasmodium biology in order to further translational research. This has been partly facilitated by targeted gene deletion strategies for the functional analysis of parasite genes. However, genes that are essential for parasite replication in erythrocytes are refractory to such methods, and require conditional knockdown or knockout approaches to dissect their function. One such approach is the TetR-DOZI system that employs multiple synthetic aptamers in the untranslated regions of target genes to control their expression in a tetracycline-dependent manner. Maintaining modified parasites with intact aptamer copies has been challenging since these repeats can be lost by recombination. By interspacing the aptamers with unique sequences, we created a stable genetic system that remains effective at controlling target gene expression. One of the most powerful approaches to understanding gene function involves turning genes on and off at will and measuring the impact at the cellular or organismal level. This particularly applies to the cohort of essential genes where traditional gene knockouts are inviable. In Plasmodium falciparum, conditional control of gene expression has been achieved by using multicomponent systems in which individual modules interact with each other to regulate DNA recombination, transcription, or posttranscriptional processes. The recently devised TetR-DOZI aptamer system relies on the ligand-regulatable interaction of a protein module with synthetic RNA aptamers to control the translation of a target gene. This technique has been successfully employed to study essential genes in P. falciparum and involves the insertion of several aptamer copies into the 3′ untranslated regions (UTRs), which provide control over mRNA fate. However, aptamer repeats are prone to recombination and one or more copies can be lost from the system, resulting in a loss of control over target gene expression. We rectified this issue by redesigning the aptamer array to minimize recombination while preserving the control elements. As proof of concept, we compared the original and modified arrays for their ability to knock down the levels of a putative essential apicoplast protein (PF3D7_0815700) and demonstrated that the modified array is highly stable and efficient. This redesign will enhance the utility of a tool that is quickly becoming a favored strategy for genetic studies in P. falciparum. IMPORTANCE Malaria elimination efforts have been repeatedly hindered by the evolution and spread of multidrug-resistant strains of Plasmodium falciparum. The absence of a commercially available vaccine emphasizes the need for a better understanding of Plasmodium biology in order to further translational research. This has been partly facilitated by targeted gene deletion strategies for the functional analysis of parasite genes. However, genes that are essential for parasite replication in erythrocytes are refractory to such methods, and require conditional knockdown or knockout approaches to dissect their function. One such approach is the TetR-DOZI system that employs multiple synthetic aptamers in the untranslated regions of target genes to control their expression in a tetracycline-dependent manner. Maintaining modified parasites with intact aptamer copies has been challenging since these repeats can be lost by recombination. By interspacing the aptamers with unique sequences, we created a stable genetic system that remains effective at controlling target gene expression.
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17
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Goodman CD, Uddin T, Spillman NJ, McFadden GI. A single point mutation in the Plasmodium falciparum FtsH1 metalloprotease confers actinonin resistance. eLife 2020; 9:58629. [PMID: 32678064 PMCID: PMC7386903 DOI: 10.7554/elife.58629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 07/17/2020] [Indexed: 11/24/2022] Open
Abstract
The antibiotic actinonin kills malaria parasites (Plasmodium falciparum) by interfering with apicoplast function. Early evidence suggested that actinonin inhibited prokaryote-like post-translational modification in the apicoplast; mimicking its activity against bacteria. However, Amberg Johnson et al. (2017) identified the metalloprotease TgFtsH1 as the target of actinonin in the related parasite Toxoplasma gondii and implicated P. falciparum FtsH1 as a likely target in malaria parasites. The authors were not, however, able to recover actinonin resistant malaria parasites, leaving the specific target of actinonin uncertain. We generated actinonin resistant P. falciparum by in vitro selection and identified a specific sequence change in PfFtsH1 associated with resistance. Introduction of this point mutation using CRISPr-Cas9 allelic replacement was sufficient to confer actinonin resistance in P. falciparum. Our data unequivocally identify PfFtsH1 as the target of actinonin and suggests that actinonin should not be included in the highly valuable collection of ‘irresistible’ drugs for combatting malaria.
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Affiliation(s)
| | - Taher Uddin
- School of BioSciences, University of Melbourne, Parkville, Australia
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18
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Swift RP, Rajaram K, Liu HB, Dziedzic A, Jedlicka AE, Roberts AD, Matthews KA, Jhun H, Bumpus NN, Tewari SG, Wallqvist A, Prigge ST. A mevalonate bypass system facilitates elucidation of plastid biology in malaria parasites. PLoS Pathog 2020; 16:e1008316. [PMID: 32059044 PMCID: PMC7046295 DOI: 10.1371/journal.ppat.1008316] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 02/27/2020] [Accepted: 01/10/2020] [Indexed: 12/03/2022] Open
Abstract
Malaria parasites rely on a plastid organelle for survival during the blood stages of infection. However, the entire organelle is dispensable as long as the isoprenoid precursor, isopentenyl pyrophosphate (IPP), is supplemented in the culture medium. We engineered parasites to produce isoprenoid precursors from a mevalonate-dependent pathway, creating a parasite line that replicates normally after the loss of the apicoplast organelle. We show that carbon-labeled mevalonate is specifically incorporated into isoprenoid products, opening new avenues for researching this essential class of metabolites in malaria parasites. We also show that essential apicoplast proteins, such as the enzyme target of the drug fosmidomycin, can be deleted in this mevalonate bypass parasite line, providing a new method to determine the roles of other important apicoplast-resident proteins. Several antibacterial drugs kill malaria parasites by targeting basic processes, such as transcription, in the organelle. We used metabolomic and transcriptomic methods to characterize parasite metabolism after azithromycin treatment triggered loss of the apicoplast and found that parasite metabolism and the production of apicoplast proteins is largely unaltered. These results provide insight into the effects of apicoplast-disrupting drugs, several of which have been used to treat malaria infections in humans. Overall, the mevalonate bypass system provides a way to probe essential aspects of apicoplast biology and study the effects of drugs that target apicoplast processes. Malaria parasites rely on an organelle called the apicoplast for growth and survival. Antimalarial drugs such as azithromycin inhibit basic processes in the apicoplast and result in the disruption of the organelle. Surprisingly, addition of a single metabolite, isopentenyl pyrophosphate (IPP), allows the parasites to survive in culture after disruption of the apicoplast. Unfortunately, using IPP to study this phenomenon has several limitations: IPP is prohibitively expensive, has to be used at high concentrations, and has a half-life less than 5 hours. To address these problems, we engineered parasites to express four enzymes from an alternative pathway capable of producing IPP in the parasites. We validated this new system and used it to metabolically label essential metabolites, to delete an essential apicoplast protein, and to characterize the state of apicoplast-disrupted parasites. A key finding from these studies comes from transcriptomic and metabolomic analysis of parasites treated with the drug azithromycin. We found that apicoplast disruption results in few changes in parasite metabolism. In particular, the expression of hundreds of nuclear-encoded apicoplast proteins are not affected by disruption of the apicoplast organelle, making it likely that apicoplast metabolic pathways and processes are still functional in apicoplast-disrupted parasites.
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Affiliation(s)
- Russell P. Swift
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Krithika Rajaram
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Hans B. Liu
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Amanda Dziedzic
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Anne E. Jedlicka
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Aleah D. Roberts
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Krista A. Matthews
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Hugo Jhun
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Namandje N. Bumpus
- Department of Medicine (Division of Clinical Pharmacology), Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Shivendra G. Tewari
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Ft. Detrick, Maryland, United States of America
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, Maryland, United States of America
| | - Anders Wallqvist
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Ft. Detrick, Maryland, United States of America
| | - Sean T. Prigge
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
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19
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Battersby BJ, Richter U, Safronov O. Mitochondrial Nascent Chain Quality Control Determines Organelle Form and Function. ACS Chem Biol 2019; 14:2396-2405. [PMID: 31498990 DOI: 10.1021/acschembio.9b00518] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Proteotoxicity has long been considered a key factor in mitochondrial dysfunction and human disease. The origin of the endogenous offending toxic substrates and the regulatory pathways to deal with these insults, however, have remained unclear. Mitochondria maintain a compartmentalized gene expression system that in animals is only responsible for synthesis of 1% of the organelle proteome. Because of the relatively small contribution of the mitochondrial genome to the overall proteome, the synthesis and quality control of these nascent chains to maintain organelle proteostasis has long been overlooked. However, recent research has uncovered mechanisms by which defects to the quality control of mitochondrial gene expression are linked to a novel cellular stress response that impinges upon organelle form and function and cell fitness. In this review, we discuss the mechanisms for a key event in the response: activation of the metalloprotease OMA1. This severs the membrane tether of the dynamin-related GTPase OPA1, which is a critical determinant for mitochondrial morphology and function. We also highlight the evolutionary conservation from bacteria of these quality-control mechanisms to maintain membrane integrity, gene expression, and cell fitness.
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Affiliation(s)
| | - Uwe Richter
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
| | - Omid Safronov
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
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20
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Cowell AN, Winzeler EA. Advances in omics-based methods to identify novel targets for malaria and other parasitic protozoan infections. Genome Med 2019; 11:63. [PMID: 31640748 PMCID: PMC6805675 DOI: 10.1186/s13073-019-0673-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 09/13/2019] [Indexed: 01/23/2023] Open
Abstract
A major advance in antimalarial drug discovery has been the shift towards cell-based phenotypic screening, with notable progress in the screening of compounds against the asexual blood stage, liver stage, and gametocytes. A primary method for drug target deconvolution in Plasmodium falciparum is in vitro evolution of compound-resistant parasites followed by whole-genome scans. Several of the most promising antimalarial drug targets, such as translation elongation factor 2 (eEF2) and phenylalanine tRNA synthetase (PheRS), have been identified or confirmed using this method. One drawback of this method is that if a mutated gene is uncharacterized, a substantial effort may be required to determine whether it is a drug target, a drug resistance gene, or if the mutation is merely a background mutation. Thus, the availability of high-throughput, functional genomic datasets can greatly assist with target deconvolution. Studies mapping genome-wide essentiality in P. falciparum or performing transcriptional profiling of the host and parasite during liver-stage infection with P. berghei have identified potentially druggable pathways. Advances in mapping the epigenomic regulation of the malaria parasite genome have also enabled the identification of key processes involved in parasite development. In addition, the examination of the host genome during infection has identified novel gene candidates associated with susceptibility to severe malaria. Here, we review recent studies that have used omics-based methods to identify novel targets for interventions against protozoan parasites, focusing on malaria, and we highlight the advantages and limitations of the approaches used. These approaches have also been extended to other protozoan pathogens, including Toxoplasma, Trypanosoma, and Leishmania spp., and these studies highlight how drug discovery efforts against these pathogens benefit from the utilization of diverse omics-based methods to identify promising drug targets.
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Affiliation(s)
- Annie N Cowell
- Division of Infectious Diseases and Global Health, Department of Medicine, University of California, San Diego, Gilman Drive, La Jolla, CA, 92093, USA.
| | - Elizabeth A Winzeler
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, Gilman Drive, La Jolla, CA, 92093, USA
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21
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Kennedy K, Crisafulli EM, Ralph SA. Delayed Death by Plastid Inhibition in Apicomplexan Parasites. Trends Parasitol 2019; 35:747-759. [PMID: 31427248 DOI: 10.1016/j.pt.2019.07.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/25/2019] [Accepted: 07/26/2019] [Indexed: 01/11/2023]
Abstract
The discovery of a plastid in apicomplexan parasites was hoped to be a watershed moment in the treatment of parasitic diseases as it revealed drug targets that are implicitly divergent from host molecular processes. Indeed, this organelle, known as the apicoplast, has since been a productive therapeutic target for pharmaceutical interventions against infections by Plasmodium, Toxoplasma, Babesia, and Theileria. However, some inhibitors of the apicoplast are restricted in their treatment utility because of their slow-kill kinetics, and this characteristic is called the delayed death effect. Here we review the recent genetic and pharmacological experiments that interrogate the causes of delayed death and explore the foundation of this phenomenon in Plasmodium and Toxoplasma parasites.
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Affiliation(s)
- Kit Kennedy
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Emily M Crisafulli
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Stuart A Ralph
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, 3010, Australia.
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22
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Targeting the apicoplast in malaria. Biochem Soc Trans 2019; 47:973-983. [PMID: 31383817 DOI: 10.1042/bst20170563] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 05/22/2019] [Accepted: 06/10/2019] [Indexed: 12/25/2022]
Abstract
Malaria continues to be one of the leading causes of human mortality in the world, and the therapies available are insufficient for eradication. Severe malaria is caused by the apicomplexan parasite Plasmodium falciparum Apicomplexan parasites, including the Plasmodium spp., are descendants of photosynthetic algae, and therefore they possess an essential plastid organelle, named the apicoplast. Since humans and animals have no plastids, the apicoplast is an attractive target for drug development. Indeed, after its discovery, the apicoplast was found to host the target pathways of some known antimalarial drugs, which motivated efforts for further research into its biological functions and biogenesis. Initially, many apicoplast inhibitions were found to result in 'delayed death', whereby parasite killing is seen only at the end of one invasion-egress cycle. This slow action is not in line with the current standard for antimalarials, which seeded scepticism about the potential of compounds targeting apicoplast functions as good candidates for drug development. Intriguingly, recent evidence of apicoplast inhibitors causing rapid killing could put this organelle back in the spotlight. We provide an overview of drugs known to inhibit apicoplast pathways, alongside recent findings in apicoplast biology that may provide new avenues for drug development.
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23
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Tang Y, Meister TR, Walczak M, Pulkoski-Gross MJ, Hari SB, Sauer RT, Amberg-Johnson K, Yeh E. A mutagenesis screen for essential plastid biogenesis genes in human malaria parasites. PLoS Biol 2019; 17:e3000136. [PMID: 30726238 PMCID: PMC6380595 DOI: 10.1371/journal.pbio.3000136] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/19/2019] [Indexed: 02/06/2023] Open
Abstract
Endosymbiosis has driven major molecular and cellular innovations. Plasmodium spp. parasites that cause malaria contain an essential, non-photosynthetic plastid-the apicoplast-which originated from a secondary (eukaryote-eukaryote) endosymbiosis. To discover organellar pathways with evolutionary and biomedical significance, we performed a mutagenesis screen for essential genes required for apicoplast biogenesis in Plasmodium falciparum. Apicoplast(-) mutants were isolated using a chemical rescue that permits conditional disruption of the apicoplast and a new fluorescent reporter for organelle loss. Five candidate genes were validated (out of 12 identified), including a triosephosphate isomerase (TIM)-barrel protein that likely derived from a core metabolic enzyme but evolved a new activity. Our results demonstrate, to our knowledge, the first forward genetic screen to assign essential cellular functions to unannotated P. falciparum genes. A putative TIM-barrel enzyme and other newly identified apicoplast biogenesis proteins open opportunities to discover new mechanisms of organelle biogenesis, molecular evolution underlying eukaryotic diversity, and drug targets against multiple parasitic diseases.
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Affiliation(s)
- Yong Tang
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Thomas R. Meister
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Marta Walczak
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Michael J. Pulkoski-Gross
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Sanjay B. Hari
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Robert T. Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Katherine Amberg-Johnson
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Ellen Yeh
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
- Chan Zuckerberg Biohub, San Francisco, California, United States of America
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24
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Host Cell Metabolism Contributes to Delayed-Death Kinetics of Apicoplast Inhibitors in Toxoplasma gondii. Antimicrob Agents Chemother 2019; 63:AAC.01646-18. [PMID: 30455243 PMCID: PMC6355570 DOI: 10.1128/aac.01646-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 11/08/2018] [Indexed: 01/24/2023] Open
Abstract
Toxoplasma gondii and related human parasites contain an essential plastid organelle called the apicoplast. Clinically used antibiotics and other inhibitors that disrupt apicoplast biogenesis cause a mysterious “delayed-death” phenotype in which parasite growth is unaffected during the first lytic cycle of inhibitor treatment but is severely inhibited in the second lytic cycle even after drug removal. Toxoplasma gondii and related human parasites contain an essential plastid organelle called the apicoplast. Clinically used antibiotics and other inhibitors that disrupt apicoplast biogenesis cause a mysterious “delayed-death” phenotype in which parasite growth is unaffected during the first lytic cycle of inhibitor treatment but is severely inhibited in the second lytic cycle even after drug removal. Critical to understanding the complex downstream cellular effects of these drug classes are the timing of apicoplast loss during inhibitor treatment and how it relates to this peculiar growth phenotype. Here we show that, upon treatment with diverse classes of apicoplast inhibitors, newly replicated T. gondii parasites in the first lytic cycle initially form apicoplasts with defects in protein import or genome replication and eventually fail to inherit the apicoplast altogether. Despite the accumulation of parasites with defective or missing apicoplasts, growth is unaffected during the first lytic cycle, as previously observed. Strikingly, concomitant inhibition of host cell isoprenoid biosynthesis results in growth inhibition in the first lytic cycle and unmasks the apicoplast defects. These results suggest that defects in and even the complete loss of the apicoplast in T. gondii are partially rescued by scavenging of host cell metabolites, leading to death that is delayed. Our findings uncover host cell interactions that can alleviate apicoplast inhibition and highlight key differences in delayed-death inhibitors between T. gondii and Plasmodium falciparum.
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25
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Richter U, Ng KY, Suomi F, Marttinen P, Turunen T, Jackson C, Suomalainen A, Vihinen H, Jokitalo E, Nyman TA, Isokallio MA, Stewart JB, Mancini C, Brusco A, Seneca S, Lombès A, Taylor RW, Battersby BJ. Mitochondrial stress response triggered by defects in protein synthesis quality control. Life Sci Alliance 2019; 2:2/1/e201800219. [PMID: 30683687 PMCID: PMC6348486 DOI: 10.26508/lsa.201800219] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 01/16/2019] [Accepted: 01/17/2019] [Indexed: 12/11/2022] Open
Abstract
Quality control defects of mitochondrial nascent chain synthesis trigger a sequential stress response characterized by OMA1 activation and ribosome decay, determining mitochondrial form and function. Mitochondria have a compartmentalized gene expression system dedicated to the synthesis of membrane proteins essential for oxidative phosphorylation. Responsive quality control mechanisms are needed to ensure that aberrant protein synthesis does not disrupt mitochondrial function. Pathogenic mutations that impede the function of the mitochondrial matrix quality control protease complex composed of AFG3L2 and paraplegin cause a multifaceted clinical syndrome. At the cell and molecular level, defects to this quality control complex are defined by impairment to mitochondrial form and function. Here, we establish the etiology of these phenotypes. We show how disruptions to the quality control of mitochondrial protein synthesis trigger a sequential stress response characterized first by OMA1 activation followed by loss of mitochondrial ribosomes and by remodelling of mitochondrial inner membrane ultrastructure. Inhibiting mitochondrial protein synthesis with chloramphenicol completely blocks this stress response. Together, our data establish a mechanism linking major cell biological phenotypes of AFG3L2 pathogenesis and show how modulation of mitochondrial protein synthesis can exert a beneficial effect on organelle homeostasis.
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Affiliation(s)
- Uwe Richter
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Kah Ying Ng
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Fumi Suomi
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Paula Marttinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Taina Turunen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Christopher Jackson
- Research Programs Unit-Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - Anu Suomalainen
- Research Programs Unit-Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - Helena Vihinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Tuula A Nyman
- Department of Immunology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
| | | | - James B Stewart
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Cecilia Mancini
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Sara Seneca
- Center for Medical Genetics/Research Center Reproduction and Genetics, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Anne Lombès
- Faculté de médecine Cochin, Institut Cochin Institut national de la santé et de la recherche médicale U1016, Centre national de la recherche scientifique Unités Mixtes de Recherche 8104, Université Paris 5, Paris, France
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
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Boucher MJ, Yeh E. Disruption of Apicoplast Biogenesis by Chemical Stabilization of an Imported Protein Evades the Delayed-Death Phenotype in Malaria Parasites. mSphere 2019; 4:e00710-18. [PMID: 30674649 PMCID: PMC6344605 DOI: 10.1128/msphere.00710-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 01/04/2019] [Indexed: 11/20/2022] Open
Abstract
Malaria parasites (Plasmodium spp.) contain a nonphotosynthetic plastid organelle called the apicoplast, which houses essential metabolic pathways and is required throughout the parasite life cycle. The biogenesis pathways responsible for apicoplast growth, division, and inheritance are of key interest as potential drug targets. Unfortunately, several known apicoplast biogenesis inhibitors are of limited clinical utility because they cause a peculiar "delayed-death" phenotype in which parasites do not stop replicating until the second lytic cycle posttreatment. Identifying apicoplast biogenesis pathways that avoid the delayed-death phenomenon is a priority. Here, we generated parasites targeting a murine dihydrofolate reductase (mDHFR) domain, which can be conditionally stabilized with the compound WR99210, to the apicoplast. Surprisingly, chemical stabilization of this exogenous fusion protein disrupted parasite growth in an apicoplast-specific manner after a single lytic cycle. WR99210-treated parasites exhibited an apicoplast biogenesis defect beginning within the same lytic cycle as drug treatment, indicating that stabilized mDHFR perturbs a non-delayed-death biogenesis pathway. While the precise mechanism-of-action of the stabilized fusion is still unclear, we hypothesize that it inhibits apicoplast protein import by stalling within and blocking translocons in the apicoplast membranes.IMPORTANCE Malaria is a major cause of global childhood mortality. To sustain progress in disease control made in the last decade, new antimalarial therapies are needed to combat emerging drug resistance. Malaria parasites contain a relict chloroplast called the apicoplast, which harbors new targets for drug discovery. Unfortunately, some drugs targeting apicoplast pathways exhibit a delayed-death phenotype, which results in a slow onset-of-action that precludes their use as fast-acting, frontline therapies. Identification of druggable apicoplast biogenesis factors that will avoid the delayed-death phenotype is an important priority. Here, we find that chemical stabilization of an apicoplast-targeted mDHFR domain disrupts apicoplast biogenesis and inhibits parasite growth after a single lytic cycle, suggesting a non-delayed-death target. Our finding indicates that further interrogation of the mechanism-of-action of this exogenous fusion protein may reveal novel therapeutic avenues.
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Affiliation(s)
- Michael J Boucher
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Ellen Yeh
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
- Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
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Kalel VC, Mäser P, Sattler M, Erdmann R, Popowicz GM. Come, sweet death: targeting glycosomal protein import for antitrypanosomal drug development. Curr Opin Microbiol 2018; 46:116-122. [PMID: 30481613 DOI: 10.1016/j.mib.2018.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 11/09/2018] [Indexed: 01/18/2023]
Abstract
Glycosomes evolved as specialized system for glycolysis in trypanosomatids. These organelle rely on protein import to maintain function. A machinery of peroxin (PEX) proteins is responsible for recognition and transport of glycosomal proteins to the organelle. Disruption of PEX-based import system was expected to be a strategy against trypanosomatids. Recently, a proof of this hypothesis has been presented. Here, we review current information about trypanosomatids' glycosomal transport components as targets for new trypanocidal therapies.
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Affiliation(s)
- Vishal C Kalel
- Institute of Biochemistry and Pathobiochemistry, Department of Systems Biochemistry, Faculty of Medicine, Ruhr University Bochum, 44780 Bochum, Germany
| | - Pascal Mäser
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland; University of Basel, 4001 Basel, Switzerland
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany; Center for Integrated Protein Science Munich at Chair of Biomolecular NMR, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Ralf Erdmann
- Institute of Biochemistry and Pathobiochemistry, Department of Systems Biochemistry, Faculty of Medicine, Ruhr University Bochum, 44780 Bochum, Germany
| | - Grzegorz M Popowicz
- Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany; Center for Integrated Protein Science Munich at Chair of Biomolecular NMR, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany.
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Kudyba HM, Cobb DW, Florentin A, Krakowiak M, Muralidharan V. CRISPR/Cas9 Gene Editing to Make Conditional Mutants of Human Malaria Parasite P. falciparum. J Vis Exp 2018. [PMID: 30295650 DOI: 10.3791/57747] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Malaria is a significant cause of morbidity and mortality worldwide. This disease, which primarily affects those living in tropical and subtropical regions, is caused by infection with Plasmodium parasites. The development of more effective drugs to combat malaria can be accelerated by improving our understanding of the biology of this complex parasite. Genetic manipulation of these parasites is key to understanding their biology; however, historically the genome of P. falciparum has been difficult to manipulate. Recently, CRISPR/Cas9 genome editing has been utilized in malaria parasites, allowing for easier protein tagging, generation of conditional protein knockdowns, and deletion of genes. CRISPR/Cas9 genome editing has proven to be a powerful tool for advancing the field of malaria research. Here, we describe a CRISPR/Cas9 method for generating glmS-based conditional knockdown mutants in P. falciparum. This method is highly adaptable to other types of genetic manipulations, including protein tagging and gene knockouts.
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Affiliation(s)
- Heather M Kudyba
- Department of Cellular Biology, University of Georgia; Center for Tropical and Emerging Global Diseases, University of Georgia
| | - David W Cobb
- Department of Cellular Biology, University of Georgia
| | - Anat Florentin
- Department of Cellular Biology, University of Georgia; Center for Tropical and Emerging Global Diseases, University of Georgia
| | | | - Vasant Muralidharan
- Department of Cellular Biology, University of Georgia; Center for Tropical and Emerging Global Diseases, University of Georgia;
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29
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Boucher MJ, Ghosh S, Zhang L, Lal A, Jang SW, Ju A, Zhang S, Wang X, Ralph SA, Zou J, Elias JE, Yeh E. Integrative proteomics and bioinformatic prediction enable a high-confidence apicoplast proteome in malaria parasites. PLoS Biol 2018; 16:e2005895. [PMID: 30212465 PMCID: PMC6155542 DOI: 10.1371/journal.pbio.2005895] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 09/25/2018] [Accepted: 08/28/2018] [Indexed: 12/20/2022] Open
Abstract
Malaria parasites (Plasmodium spp.) and related apicomplexan pathogens contain a nonphotosynthetic plastid called the apicoplast. Derived from an unusual secondary eukaryote-eukaryote endosymbiosis, the apicoplast is a fascinating organelle whose function and biogenesis rely on a complex amalgamation of bacterial and algal pathways. Because these pathways are distinct from the human host, the apicoplast is an excellent source of novel antimalarial targets. Despite its biomedical importance and evolutionary significance, the absence of a reliable apicoplast proteome has limited most studies to the handful of pathways identified by homology to bacteria or primary chloroplasts, precluding our ability to study the most novel apicoplast pathways. Here, we combine proximity biotinylation-based proteomics (BioID) and a new machine learning algorithm to generate a high-confidence apicoplast proteome consisting of 346 proteins. Critically, the high accuracy of this proteome significantly outperforms previous prediction-based methods and extends beyond other BioID studies of unique parasite compartments. Half of identified proteins have unknown function, and 77% are predicted to be important for normal blood-stage growth. We validate the apicoplast localization of a subset of novel proteins and show that an ATP-binding cassette protein ABCF1 is essential for blood-stage survival and plays a previously unknown role in apicoplast biogenesis. These findings indicate critical organellar functions for newly discovered apicoplast proteins. The apicoplast proteome will be an important resource for elucidating unique pathways derived from secondary endosymbiosis and prioritizing antimalarial drug targets.
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Affiliation(s)
- Michael J. Boucher
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Sreejoyee Ghosh
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
| | - Lichao Zhang
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Avantika Lal
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Se Won Jang
- Department of Computer Science, Stanford University, Stanford, California, United States of America
| | - An Ju
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
| | - Shuying Zhang
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
| | - Xinzi Wang
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
| | - Stuart A. Ralph
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Vic, Australia
| | - James Zou
- Department of Biomedical Data Science, Stanford University School of Medicine, Stanford, California, United States of America
- Chan Zuckerberg Biohub, San Francisco, California, United States of America
| | - Joshua E. Elias
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Ellen Yeh
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
- Chan Zuckerberg Biohub, San Francisco, California, United States of America
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Luth MR, Gupta P, Ottilie S, Winzeler EA. Using in Vitro Evolution and Whole Genome Analysis To Discover Next Generation Targets for Antimalarial Drug Discovery. ACS Infect Dis 2018; 4:301-314. [PMID: 29451780 PMCID: PMC5848146 DOI: 10.1021/acsinfecdis.7b00276] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
![]()
Although
many new anti-infectives have been discovered and developed solely
using phenotypic cellular screening and assay optimization, most researchers
recognize that structure-guided drug design is more practical and
less costly. In addition, a greater chemical space can be interrogated
with structure-guided drug design. The practicality of structure-guided
drug design has launched a search for the targets of compounds discovered
in phenotypic screens. One method that has been used extensively in
malaria parasites for target discovery and chemical validation is in vitro evolution and whole genome analysis (IVIEWGA).
Here, small molecules from phenotypic screens with demonstrated antiparasitic
activity are used in genome-based target discovery methods. In this
Review, we discuss the newest, most promising druggable targets discovered
or further validated by evolution-based methods, as well as some exceptions.
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Affiliation(s)
- Madeline R. Luth
- Division of Host Pathogen Systems and Therapeutics, Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Purva Gupta
- Division of Host Pathogen Systems and Therapeutics, Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Sabine Ottilie
- Division of Host Pathogen Systems and Therapeutics, Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Elizabeth A. Winzeler
- Division of Host Pathogen Systems and Therapeutics, Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
- Skaggs School of Pharmaceutical Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
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ATG8 Is Essential Specifically for an Autophagy-Independent Function in Apicoplast Biogenesis in Blood-Stage Malaria Parasites. mBio 2018; 9:mBio.02021-17. [PMID: 29295911 PMCID: PMC5750400 DOI: 10.1128/mbio.02021-17] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Plasmodium parasites and related pathogens contain an essential nonphotosynthetic plastid organelle, the apicoplast, derived from secondary endosymbiosis. Intriguingly, a highly conserved eukaryotic protein, autophagy-related protein 8 (ATG8), has an autophagy-independent function in the apicoplast. Little is known about the novel apicoplast function of ATG8 and its importance in blood-stage Plasmodium falciparum Using a P. falciparum strain in which ATG8 expression was conditionally regulated, we showed that P. falciparum ATG8 (PfATG8) is essential for parasite replication. Significantly, growth inhibition caused by the loss of PfATG8 was reversed by addition of isopentenyl pyrophosphate (IPP), which was previously shown to rescue apicoplast defects in P. falciparum Parasites deficient in PfATG8, but whose growth was rescued by IPP, had lost their apicoplast. We designed a suite of functional assays, including a new fluorescence in situ hybridization (FISH) method for detection of the low-copy-number apicoplast genome, to interrogate specific steps in apicoplast biogenesis and detect apicoplast defects which preceded the block in parasite replication. Though protein import and membrane expansion of the apicoplast were unaffected, the apicoplast was not inherited by daughter parasites. Our findings demonstrate that, though multiple autophagy-dependent and independent functions have been proposed for PfATG8, only its role in apicoplast biogenesis is essential in blood-stage parasites. We propose that PfATG8 is required for fission or segregation of the apicoplast during parasite replication.IMPORTANCEPlasmodium parasites, which cause malaria, and related apicomplexan parasites are important human and veterinary pathogens. They are evolutionarily distant from traditional model organisms and possess a unique plastid organelle, the apicoplast, acquired by an unusual eukaryote-eukaryote endosymbiosis which established novel protein/lipid import and organelle inheritance pathways in the parasite cell. Though the apicoplast is essential for parasite survival in all stages of its life cycle, little is known about these novel biogenesis pathways. We show that malaria parasites have adapted a highly conserved protein required for macroautophagy in yeast and mammals to function specifically in apicoplast inheritance. Our finding elucidates a novel mechanism of organelle biogenesis, essential for pathogenesis, in this divergent branch of pathogenic eukaryotes.
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Gisselberg JE, Herrera Z, Orchard LM, Llinás M, Yeh E. Specific Inhibition of the Bifunctional Farnesyl/Geranylgeranyl Diphosphate Synthase in Malaria Parasites via a New Small-Molecule Binding Site. Cell Chem Biol 2017; 25:185-193.e5. [PMID: 29276048 DOI: 10.1016/j.chembiol.2017.11.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/24/2017] [Accepted: 11/22/2017] [Indexed: 12/19/2022]
Abstract
The bifunctional farnesyl/geranylgeranyl diphosphate synthase (FPPS/GGPPS) is a key branchpoint enzyme in isoprenoid biosynthesis in Plasmodium falciparum (malaria) parasites. PfFPPS/GGPPS is a validated, high-priority antimalarial drug target. Unfortunately, current bisphosphonate drugs that inhibit FPPS and GGPPS enzymes by acting as a diphosphate substrate analog show poor bioavailability and selectivity for PfFPPS/GGPPS. We identified a new non-bisphosphonate compound, MMV019313, which is highly selective for PfFPPS/GGPPS and showed no activity against human FPPS or GGPPS. Inhibition of PfFPPS/GGPPS by MMV019313, but not bisphosphonates, was disrupted in an S228T variant, demonstrating that MMV019313 and bisphosphonates have distinct modes of inhibition. Molecular docking indicated that MMV019313 did not bind previously characterized substrate sites in PfFPPS/GGPPS. Our finding uncovers a new, selective small-molecule binding site in this important antimalarial drug target with superior druggability compared with the known inhibitor site and sets the stage for the development of Plasmodium-specific FPPS/GGPPS inhibitors.
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Affiliation(s)
- Jolyn E Gisselberg
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA 94305, USA
| | - Zachary Herrera
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA 94305, USA
| | - Lindsey M Orchard
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA; Huck Center for Malaria Research, Pennsylvania State University, University Park, PA 16802, USA
| | - Manuel Llinás
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA; Huck Center for Malaria Research, Pennsylvania State University, University Park, PA 16802, USA; Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Ellen Yeh
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA 94305, USA; Department of Pathology, Stanford Medical School, Stanford University, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford Medical School, Stanford University, Stanford, CA 94305, USA.
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Validation of Putative Apicoplast-Targeting Drugs Using a Chemical Supplementation Assay in Cultured Human Malaria Parasites. Antimicrob Agents Chemother 2017; 62:AAC.01161-17. [PMID: 29109165 DOI: 10.1128/aac.01161-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 10/18/2017] [Indexed: 11/20/2022] Open
Abstract
Malaria parasites contain a relict plastid, the apicoplast, which is considered an excellent drug target due to its bacterial-like ancestry. Numerous parasiticidals have been proposed to target the apicoplast, but few have had their actual targets substantiated. Isopentenyl pyrophosphate (IPP) production is the sole required function of the apicoplast in the blood stage of the parasite life cycle, and IPP supplementation rescues parasites from apicoplast-perturbing drugs. Hence, any drug that kills parasites when IPP is supplied in culture must have a nonapicoplast target. Here, we use IPP supplementation to discriminate whether 23 purported apicoplast-targeting drugs are on- or off-target. We demonstrate that a prokaryotic DNA replication inhibitor (ciprofloxacin), several prokaryotic translation inhibitors (chloramphenicol, doxycycline, tetracycline, clindamycin, azithromycin, erythromycin, and clarithromycin), a tRNA synthase inhibitor (mupirocin), and two IPP synthesis pathway inhibitors (fosmidomycin and FR900098) have apicoplast targets. Intriguingly, fosmidomycin and FR900098 leave the apicoplast intact, whereas the others eventually result in apicoplast loss. Actinonin, an inhibitor of bacterial posttranslational modification, does not produce a typical delayed-death response but is rescued with IPP, thereby confirming its apicoplast target. Parasites treated with putative apicoplast fatty acid pathway inhibitors could not be rescued, demonstrating that these drugs have their primary targets outside the apicoplast, which agrees with the dispensability of the apicoplast fatty acid synthesis pathways in the blood stage of malaria parasites. IPP supplementation provides a simple test of whether a compound has a target in the apicoplast and can be used to screen novel compounds for mode of action.
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