1
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Gowda DC, Miller LH. Glycosylation in malaria parasites: what do we know? Trends Parasitol 2024; 40:131-146. [PMID: 38262838 PMCID: PMC10923157 DOI: 10.1016/j.pt.2023.12.006] [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: 10/05/2023] [Revised: 12/13/2023] [Accepted: 12/17/2023] [Indexed: 01/25/2024]
Abstract
In malaria parasites, although post-translational modification of proteins with N-. O-, and C-glycosidic bond-linked glycans is limited, it is confined to relatively fewer proteins in which the glycans are present at significant levels and may have important functions. Furthermore, several proteins are modified with glycosylphosphatidylinositols (GPIs) which represent the predominant glycan synthesized by parasites. Modification of proteins with GPIs is obligatory for parasite survival as GPI-anchored proteins (GPI-APs) play essential roles in all life cycle stages of the parasites, including development, egress, gametogenesis, motility, and host cell adhesion and invasion. Here, we discuss the current knowledge on the structures and potential functions of the glycan moieties of parasite proteins. The knowledge has important implications for the development of drugs and vaccines for malaria.
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Affiliation(s)
- D Channe Gowda
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD 20852, USA; Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA.
| | - Louis H Miller
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD 20852, USA.
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2
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Ong HW, Adderley J, Tobin AB, Drewry DH, Doerig C. Parasite and host kinases as targets for antimalarials. Expert Opin Ther Targets 2023; 27:151-169. [PMID: 36942408 DOI: 10.1080/14728222.2023.2185511] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
INTRODUCTION The deployment of Artemisinin-based combination therapies and transmission control measures led to a decrease in the global malaria burden over the recent decades. Unfortunately, this trend is now reversing, in part due to resistance against available treatments, calling for the development of new drugs against untapped targets to prevent cross-resistance. AREAS COVERED In view of their demonstrated druggability in noninfectious diseases, protein kinases represent attractive targets. Kinase-focussed antimalarial drug discovery is facilitated by the availability of kinase-targeting scaffolds and large libraries of inhibitors, as well as high-throughput phenotypic and biochemical assays. We present an overview of validated Plasmodium kinase targets and their inhibitors, and briefly discuss the potential of host cell kinases as targets for host-directed therapy. EXPERT OPINION We propose priority research areas, including (i) diversification of Plasmodium kinase targets (at present most efforts focus on a very small number of targets); (ii) polypharmacology as an avenue to limit resistance (kinase inhibitors are highly suitable in this respect); and (iii) preemptive limitation of resistance through host-directed therapy (targeting host cell kinases that are required for parasite survival) and transmission-blocking through targeting sexual stage-specific kinases as a strategy to protect curative drugs from the spread of resistance.
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Affiliation(s)
- Han Wee Ong
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC USA
| | - Jack Adderley
- Department of Laboratory Medicine, School of Health and Biomedical Sciences, Rmit University, Bundoora VIC Australia
| | - Andrew B Tobin
- Advanced Research Centre, University of Glasgow, Glasgow, UK
| | - David H Drewry
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC USA
| | - Christian Doerig
- Department of Laboratory Medicine, School of Health and Biomedical Sciences, Rmit University, Bundoora VIC Australia
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3
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Galal KA, Truong A, Kwarcinski F, de Silva C, Avalani K, Havener TM, Chirgwin ME, Merten E, Ong HW, Willis C, Abdelwaly A, Helal MA, Derbyshire ER, Zutshi R, Drewry DH. Identification of Novel 2,4,5-Trisubstituted Pyrimidines as Potent Dual Inhibitors of Plasmodial PfGSK3/ PfPK6 with Activity against Blood Stage Parasites In Vitro. J Med Chem 2022; 65:13172-13197. [PMID: 36166733 PMCID: PMC9574854 DOI: 10.1021/acs.jmedchem.2c00996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Essential plasmodial kinases PfGSK3
and PfPK6 are considered novel drug targets to combat
rising
resistance to traditional antimalarial therapy. Herein, we report
the discovery of IKK16 as a dual PfGSK3/PfPK6 inhibitor active against blood stage Pf3D7 parasites. To establish structure–activity relationships
for PfPK6 and PfGSK3, 52 analogues
were synthesized and assessed for the inhibition of PfGSK3 and PfPK6, with potent inhibitors further assessed
for activity against blood and liver stage parasites. This culminated
in the discovery of dual PfGSK3/PfPK6 inhibitors 23d (PfGSK3/PfPK6 IC50 = 172/11 nM) and 23e (PfGSK3/PfPK6 IC50 = 97/8 nM)
with antiplasmodial activity (23dPf3D7 EC50 = 552 ± 37 nM and 23ePf3D7 EC50 = 1400 ± 13 nM). However, both
compounds exhibited significant promiscuity when tested in a panel
of human kinase targets. Our results demonstrate that dual PfPK6/PfGSK3 inhibitors with antiplasmodial
activity can be identified and can set the stage for further optimization
efforts.
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Affiliation(s)
- Kareem A Galal
- Structural Genomics Consortium and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Anna Truong
- Department of Chemistry, Duke University, 124 Science Drive, Durham, North Carolina 27708, United States
| | - Frank Kwarcinski
- Luceome Biotechnologies, L.L.C, 1665 E. 18th Street, Suite 106, Tucson, Arizona 85719, United States
| | - Chandi de Silva
- Luceome Biotechnologies, L.L.C, 1665 E. 18th Street, Suite 106, Tucson, Arizona 85719, United States
| | - Krisha Avalani
- Luceome Biotechnologies, L.L.C, 1665 E. 18th Street, Suite 106, Tucson, Arizona 85719, United States
| | - Tammy M Havener
- Structural Genomics Consortium and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Michael E Chirgwin
- Department of Chemistry, Duke University, 124 Science Drive, Durham, North Carolina 27708, United States
| | - Eric Merten
- Structural Genomics Consortium and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Han Wee Ong
- Structural Genomics Consortium and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Caleb Willis
- Luceome Biotechnologies, L.L.C, 1665 E. 18th Street, Suite 106, Tucson, Arizona 85719, United States
| | - Ahmad Abdelwaly
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza 12587, Egypt
| | - Mohamed A Helal
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza 12587, Egypt.,Medicinal Chemistry Department, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt
| | - Emily R Derbyshire
- Department of Chemistry, Duke University, 124 Science Drive, Durham, North Carolina 27708, United States.,Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, Durham, North Carolina 27710, United States
| | - Reena Zutshi
- Luceome Biotechnologies, L.L.C, 1665 E. 18th Street, Suite 106, Tucson, Arizona 85719, United States
| | - David H Drewry
- Structural Genomics Consortium and Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.,Lineberger Comprehensive Cancer Center, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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4
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Abstract
Human malaria, caused by infection with Plasmodium parasites, remains one of the most important global public health problems, with the World Health Organization reporting more than 240 million cases and 600,000 deaths annually as of 2020 (World malaria report 2021). Our understanding of the biology of these parasites is critical for development of effective therapeutics and prophylactics, including both antimalarials and vaccines. Plasmodium is a protozoan organism that is intracellular for most of its life cycle. However, to complete its complex life cycle and to allow for both amplification and transmission, the parasite must egress out of the host cell in a highly regulated manner. This review discusses the major pathways and proteins involved in the egress events during the Plasmodium life cycle-merozoite and gametocyte egress out of red blood cells, sporozoite egress out of the oocyst, and merozoite egress out of the hepatocyte. The similarities, as well as the differences, between the various egress pathways of the parasite highlight both novel cell biology and potential therapeutic targets to arrest its life cycle.
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Affiliation(s)
- Jeffrey D Dvorin
- Division of Infectious Diseases, Boston Children's Hospital, Boston, Massachusetts, USA;
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Daniel E Goldberg
- Division of Infectious Diseases, Department of Medicine; and Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA;
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5
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Functional inactivation of Plasmodium falciparum glycogen synthase kinase GSK3 modulates erythrocyte invasion and blocks gametocyte maturation. J Biol Chem 2022; 298:102360. [PMID: 35961464 PMCID: PMC9478393 DOI: 10.1016/j.jbc.2022.102360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 11/23/2022] Open
Abstract
Malaria is responsible for hundreds of thousands of deaths every year. The lack of an effective vaccine and the global spread of multidrug resistant parasites hampers the fight against the disease and underlines the need for new antimalarial drugs. Central to the pathogenesis of malaria is the proliferation of Plasmodium parasites within human erythrocytes. Parasites invade erythrocytes via a coordinated sequence of receptor–ligand interactions between the parasite and the host cell. Posttranslational modifications such as protein phosphorylation are known to be key regulators in this process and are mediated by protein kinases. For several parasite kinases, including the Plasmodium falciparum glycogen synthase kinase 3 (PfGSK3), inhibitors have been shown to block erythrocyte invasion. Here, we provide an assessment of PfGSK3 function by reverse genetics. Using targeted gene disruption, we show the active gene copy, PfGSK3β, is not essential for asexual blood stage proliferation, although it modulates efficient erythrocyte invasion. We found functional inactivation leads to a 69% decreased growth rate and confirmed this growth defect by rescue experiments with wildtype and catalytically inactive mutants. Functional knockout of PfGSK3β does not lead to transcriptional upregulation of the second copy of PfGSK3. We further analyze expression, localization, and function of PfGSK3β during gametocytogenesis using a parasite line allowing conditional induction of sexual commitment. We demonstrate PfGSK3β-deficient gametocytes show a strikingly malformed morphology leading to the death of parasites in later stages of gametocyte development. Taken together, these findings are important for our understanding and the development of PfGSK3 as an antimalarial target.
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6
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N-terminal phosphorylation regulates the activity of Glycogen Synthase Kinase 3 from Plasmodium falciparum. Biochem J 2022; 479:337-356. [PMID: 35023554 PMCID: PMC8883495 DOI: 10.1042/bcj20210829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 01/09/2022] [Accepted: 01/12/2022] [Indexed: 11/17/2022]
Abstract
As the decline of malaria cases stalled over the last five years, novel targets in Plasmodium falciparum are necessary for the development of new drugs. Glycogen Synthase Kinase (PfGSK3) has been identified as a potential target, since its selective inhibitors were shown to disrupt the parasitès life cycle. In the uncanonical N-terminal region of the parasite enzyme, we identified several autophosphorylation sites and probed their role in activity regulation of PfGSK3. By combining molecular modeling with experimental small-angle X-ray scattering data, we show that increased PfGSK3 activity is promoted by conformational changes in the PfGSK3 N-terminus, triggered by N-terminal phosphorylation. Our work provides novel insights into the structure and regulation of the malarial PfGSK3.
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7
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Hitz E, Wiedemar N, Passecker A, Graça BAS, Scheurer C, Wittlin S, Brancucci NMB, Vakonakis I, Mäser P, Voss TS. The 3-phosphoinositide-dependent protein kinase 1 is an essential upstream activator of protein kinase A in malaria parasites. PLoS Biol 2021; 19:e3001483. [PMID: 34879056 PMCID: PMC8687544 DOI: 10.1371/journal.pbio.3001483] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 12/20/2021] [Accepted: 11/12/2021] [Indexed: 01/11/2023] Open
Abstract
Cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) signalling is essential for the proliferation of Plasmodium falciparum malaria blood stage parasites. The mechanisms regulating the activity of the catalytic subunit PfPKAc, however, are only partially understood, and PfPKAc function has not been investigated in gametocytes, the sexual blood stage forms that are essential for malaria transmission. By studying a conditional PfPKAc knockdown (cKD) mutant, we confirm the essential role for PfPKAc in erythrocyte invasion by merozoites and show that PfPKAc is involved in regulating gametocyte deformability. We furthermore demonstrate that overexpression of PfPKAc is lethal and kills parasites at the early phase of schizogony. Strikingly, whole genome sequencing (WGS) of parasite mutants selected to tolerate increased PfPKAc expression levels identified missense mutations exclusively in the gene encoding the parasite orthologue of 3-phosphoinositide-dependent protein kinase-1 (PfPDK1). Using targeted mutagenesis, we demonstrate that PfPDK1 is required to activate PfPKAc and that T189 in the PfPKAc activation loop is the crucial target residue in this process. In summary, our results corroborate the importance of tight regulation of PfPKA signalling for parasite survival and imply that PfPDK1 acts as a crucial upstream regulator in this pathway and potential new drug target.
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Affiliation(s)
- Eva Hitz
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Natalie Wiedemar
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Armin Passecker
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Beatriz A. S. Graça
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Christian Scheurer
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Sergio Wittlin
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Nicolas M. B. Brancucci
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Ioannis Vakonakis
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Pascal Mäser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Till S. Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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8
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Ishizaki T, Asada M, Hakimi H, Chaiyawong N, Kegawa Y, Yahata K, Kaneko O. cAMP-dependent protein kinase regulates secretion of apical membrane antigen 1 (AMA1) in Plasmodium yoelii. Parasitol Int 2021; 85:102435. [PMID: 34390881 DOI: 10.1016/j.parint.2021.102435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/06/2021] [Accepted: 08/06/2021] [Indexed: 12/18/2022]
Abstract
Malaria remains a heavy global burden on human health, and it is important to understand the molecular and cellular biology of the parasite to find targets for drug and vaccine development. The mouse malaria model is an essential tool to characterize the function of identified molecules; however, robust technologies for targeted gene deletions are still poorly developed for the widely used rodent malaria parasite, Plasmodium yoelii. To overcome this problem, we established a DiCre-loxP inducible knockout (iKO) system in P. yoelii, which showed more than 80% excision efficacy of the target locus and more than 90% reduction of locus transcripts 24 h (one cell cycle) after RAP administration. Using this developed system, cAMP-dependent protein kinase (PKAc) was inducibly disrupted and the phenotypes of the resulting PKAc-iKO parasites were analyzed. We found that PKAc-iKO parasites showed severe growth and erythrocyte invasion defects. We also found that disruption of PKAc impaired the secretion of AMA1 in P. yoelii, in contrast to a report showing no role of PKAc in AMA1 secretion in P. falciparum. This discrepancy may be related to the difference in the timing of AMA1 distribution to the merozoite surface, which occurs just after egress for P. falciparum, but after several minutes for P. yoelii. Secretions of PyEBL, Py235, and RON2 were not affected by the disruption of PKAc in P. yoelii. PyRON2 was already secreted to the merozoite surface immediately after merozoite egress, which is inconsistent with the current model that RON2 is injected into the erythrocyte cytosol. Further investigations are required to understand the role of RON2 exposed on the merozoite surface.
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Affiliation(s)
- Takahiro Ishizaki
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate school of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå University, Umeå 901 87, Sweden
| | - Masahito Asada
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate school of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-11, Obihiro, Hokkaido 080-0834, Japan.
| | - Hassan Hakimi
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College station, TX 77843, USA.
| | - Nattawat Chaiyawong
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate school of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Yuto Kegawa
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate school of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Section on Integrative Biophysics, Eunice Kennedy Shriver National Institutes of Child Health and Human Development, National Institute of Health, 9000 Rockville Pike, Bethesda, Mary land 20892, USA
| | - Kazuhide Yahata
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
| | - Osamu Kaneko
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate school of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
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9
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Jonsdottir TK, Gabriela M, Crabb BS, F de Koning-Ward T, Gilson PR. Defining the Essential Exportome of the Malaria Parasite. Trends Parasitol 2021; 37:664-675. [PMID: 33985912 DOI: 10.1016/j.pt.2021.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/15/2021] [Accepted: 04/15/2021] [Indexed: 02/06/2023]
Abstract
To survive inside red blood cells (RBCs), malaria parasites export many proteins to alter their host cell's physiological properties. Although most proteins of this exportome are involved in immune avoidance or in the trafficking of exported proteins to the host membrane, about 20% are essential for parasite survival in culture but little is known about their biological functions. Here, we have combined information from large-scale genetic screens and targeted gene-disruption studies to tabulate all currently known Plasmodium falciparum exported proteins according to their likelihood of being essential. We also discuss the essential functional pathways that exported proteins might be involved in to help direct research efforts towards a more comprehensive understanding of host-cell remodelling.
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Affiliation(s)
- Thorey K Jonsdottir
- Burnet Institute, Melbourne, Victoria 3004, Australia; Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Mikha Gabriela
- Burnet Institute, Melbourne, Victoria 3004, Australia; School of Medicine, Deakin University, Waurn Ponds, Victoria 3216, Australia
| | - Brendan S Crabb
- Burnet Institute, Melbourne, Victoria 3004, Australia; Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | | | - Paul R Gilson
- Burnet Institute, Melbourne, Victoria 3004, Australia.
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10
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Ramanto KN, Nurdiansyah R. Immunogenicity and structural efficacy of P41 of Plasmodium sp. as potential cross-species blood-stage malaria vaccine. Comput Biol Chem 2021; 92:107493. [PMID: 33962170 DOI: 10.1016/j.compbiolchem.2021.107493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 04/21/2021] [Indexed: 10/21/2022]
Abstract
Vaccine based strategies offer a promising future in malaria control by generating protective immunity against natural infection. However, vaccine development is hindered by the Plasmodium sp. genetic diversity. Previously, we have shown P41 protein from 6-Cysteine shared by Plasmodium sp. and could be used for cross-species anti-malaria vaccines. Two different approaches, ancestral, and consensus sequence, could produce a single target for all human-infecting Plasmodium. In this study, we investigated the efficacy of ancestral and consensus of P41 protein. Phylogenetic and time tree reconstruction was conducted by RAXML and BEAST2 package to determine the relationship of known P41 sequences. Ancestral and consensus sequences were reconstructed by the GRASP server and Unipro Ugene software, respectively. The structural prediction was made using the Psipred and Rosetta program. The protein characteristic was analyzed by assessing hydrophobicity and Post-Translational Modification sites. Meanwhile, the immunogenicity score for B-cell, T-cell, and MHC was determined using an immunoinformatic approach. The result suggests that ancestral and consensus have a distinct protein characteristic with high immunogenicity scores for all immune cells. We found one shared conserved epitope with phosphorylation modification from the ancestral sequence to target the cross-species vaccine. Thus, this study provides detailed insight into P41 efficacy for the cross-species anti-malaria blood-stage vaccine.
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Affiliation(s)
- Kevin Nathanael Ramanto
- Department of Bioinformatics, School of Life Sciences, Indonesia International Institute for Life Sciences, Jakarta, Indonesia
| | - Rizky Nurdiansyah
- Department of Bioinformatics, School of Life Sciences, Indonesia International Institute for Life Sciences, Jakarta, Indonesia.
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11
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Thiam LG, Nyarko PB, Kusi KA, Niang M, Aniweh Y, Awandare GA. Blood donor variability is a modulatory factor for P. falciparum invasion phenotyping assays. Sci Rep 2021; 11:7129. [PMID: 33782439 PMCID: PMC8007732 DOI: 10.1038/s41598-021-86438-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 03/12/2021] [Indexed: 11/26/2022] Open
Abstract
Human erythrocytes are indispensable for Plasmodium falciparum development. Unlike other eukaryotic cells, there is no existing erythroid cell line capable of supporting long-term P. falciparum in vitro experiments. Consequently, invasion phenotyping experiments rely on erythrocytes of different individuals. However, the contribution of the erythrocytes variation in influencing invasion rates remains unknown, which represents a challenge for conducting large-scale comparative studies. Here, we used erythrocytes of different blood groups harboring different hemoglobin genotypes to assess the relative contribution of blood donor variability in P. falciparum invasion phenotyping assays. For each donor, we investigated the relationship between parasite invasion phenotypes and erythrocyte phenotypic characteristics, including the expression levels of surface receptors (e.g. the human glycophorins A and C, the complement receptor 1 and decay accelerating factor), blood groups (e.g. ABO/Rh system), and hemoglobin genotypes (e.g. AA, AS and AC). Across all donors, there were significant differences in invasion efficiency following treatment with either neuraminidase, trypsin or chymotrypsin relative to the control erythrocytes. Primarily, we showed that the levels of key erythrocyte surface receptors and their sensitivity to enzyme treatment significantly differed across donors. However, invasion efficiency did not correlate with susceptibility to enzyme treatment or with the levels of the selected erythrocyte surface receptors. Furthermore, we found no relationship between P. falciparum invasion phenotype and blood group or hemoglobin genotype. Altogether, our findings demonstrate the need to consider erythrocyte donor uniformity and anticipate challenges associated with blood donor variability in early stages of large-scale study design.
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Affiliation(s)
- Laty G Thiam
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.,Department of Biochemistry Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.,G4 MEGA Vaccines, Institut Pasteur de Dakar, Dakar, Senegal
| | - Prince B Nyarko
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.,Department of Biochemistry Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.,Laboratory of Pathogen-Host Interaction, UMR5235, CNRS, University of Montpellier, Montpellier, France
| | - Kwadwo A Kusi
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.,Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Makhtar Niang
- Pôle Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Senegal
| | - Yaw Aniweh
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana. .,Department of Biochemistry Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.
| | - Gordon A Awandare
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana. .,Department of Biochemistry Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.
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12
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Adderley J, Williamson T, Doerig C. Parasite and Host Erythrocyte Kinomics of Plasmodium Infection. Trends Parasitol 2021; 37:508-524. [PMID: 33593681 DOI: 10.1016/j.pt.2021.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 02/06/2023]
Abstract
Malaria remains a heavy public health and socioeconomic burden in tropical and subtropical regions. Increasing resistance against front-line treatments implies that novel targets for antimalarial intervention are urgently required. Protein kinases of both the parasites and their host cells possess strong potential in this respect. We present an overview of the updated kinome of Plasmodium falciparum, the species that is the largest contributor to malaria mortality, and of current knowledge pertaining to the function of parasite-encoded protein kinases during the parasite's life cycle. Furthermore, we detail recent advances in drug initiatives targeting Plasmodium kinases and outline the potential of protein kinases in the context of the growing field of host-directed therapies, which is currently being explored as a novel way to combat parasite drug resistance.
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Affiliation(s)
- Jack Adderley
- School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC 3083, Australia
| | - Tayla Williamson
- School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC 3083, Australia
| | - Christian Doerig
- School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC 3083, Australia.
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13
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Uboldi AD, Wilde ML, Bader SM, Tonkin CJ. Environmental sensing and regulation of motility in Toxoplasma. Mol Microbiol 2020; 115:916-929. [PMID: 33278047 DOI: 10.1111/mmi.14661] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 11/27/2020] [Accepted: 12/01/2020] [Indexed: 12/28/2022]
Abstract
Toxoplasma and other apicomplexan parasites undergo a unique form of cellular locomotion referred to as "gliding motility." Gliding motility is crucial for parasite survival as it powers tissue dissemination, host cell invasion and egress. Distinct environmental cues lead to activation of gliding motility and have become a prominent focus of recent investigation. Progress has been made toward understanding what environmental cues are sensed and how these signals are transduced in order to regulate the machinery and cellular events powering gliding motility. In this review, we will discuss new findings and integrate these into our current understanding to propose a model of how environmental sensing is achieved to regulate gliding motility in Toxoplasma. Collectively, these findings also have implications for the understanding of gliding motility across Apicomplexa more broadly.
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Affiliation(s)
- Alessandro D Uboldi
- Division of Infectious Disease and Immune Defense, The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,The Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Mary-Louise Wilde
- Division of Infectious Disease and Immune Defense, The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,The Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Stefanie M Bader
- Division of Infectious Disease and Immune Defense, The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia
| | - Christopher J Tonkin
- Division of Infectious Disease and Immune Defense, The Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,The Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
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14
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Mustière R, Vanelle P, Primas N. Plasmodial Kinase Inhibitors Targeting Malaria: Recent Developments. Molecules 2020; 25:E5949. [PMID: 33334080 PMCID: PMC7765515 DOI: 10.3390/molecules25245949] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/11/2020] [Accepted: 12/11/2020] [Indexed: 11/17/2022] Open
Abstract
Recent progress in reducing malaria cases and ensuing deaths is threatened by factors like mutations that induce resistance to artemisinin derivatives. Multiple drugs are currently in clinical trials for malaria treatment, including some with novel mechanisms of action. One of these, MMV390048, is a plasmodial kinase inhibitor. This review lists the recently developed molecules which target plasmodial kinases. A systematic review of the literature was performed using CAPLUS and MEDLINE databases from 2005 to 2020. It covers a total of 60 articles and describes about one hundred compounds targeting 22 plasmodial kinases. This work highlights the strong potential of compounds targeting plasmodial kinases for future drug therapies. However, the majority of the Plasmodium kinome remains to be explored.
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Affiliation(s)
| | - Patrice Vanelle
- Aix Marseille Univ, CNRS, ICR UMR 7273, Equipe Pharmaco-Chimie Radicalaire, Faculté de Pharmacie, 13385 Marseille CEDEX 05, France;
| | - Nicolas Primas
- Aix Marseille Univ, CNRS, ICR UMR 7273, Equipe Pharmaco-Chimie Radicalaire, Faculté de Pharmacie, 13385 Marseille CEDEX 05, France;
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15
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Vo KC, Günay-Esiyok Ö, Liem N, Gupta N. The protozoan parasite Toxoplasma gondii encodes a gamut of phosphodiesterases during its lytic cycle in human cells. Comput Struct Biotechnol J 2020; 18:3861-3876. [PMID: 33335684 PMCID: PMC7720076 DOI: 10.1016/j.csbj.2020.11.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 01/21/2023] Open
Abstract
Toxoplasma genome harbors at least 18 phosphodiesterases encoded by distinct genes. Most parasite PDEs lack regulatory modules and are quite divergent from their human orthologs. Acutely-infectious tachyzoite stage of T. gondii expresses 11 PDEs with varied localizations. PDE8 and PDE9 are closely-related dual-substrate specific proteins residing in the apical pole. Homology modeling of PDE8 and PDE9 reveals a conserved 3D topology and substrate pocket. PDE9 is dispensable in tachyzoites, signifying a functional redundancy with PDE8.
Cyclic nucleotide signaling is pivotal to the asexual reproduction of Toxoplasma gondii, however little do we know about the phosphodiesterase enzymes in this widespread obligate intracellular parasite. Here, we identified 18 phosphodiesterases (TgPDE1-18) in the parasite genome, most of which form apicomplexan-specific clades and lack archetypal regulatory motifs often found in mammalian PDEs. Genomic epitope-tagging in the tachyzoite stage showed the expression of 11 phosphodiesterases with diverse subcellular distributions. Notably, TgPDE8 and TgPDE9 are located in the apical plasma membrane to regulate cAMP and cGMP signaling, as suggested by their dual-substrate catalysis and structure modeling. TgPDE9 expression can be ablated with no apparent loss of growth fitness in tachyzoites. Likewise, the redundancy in protein expression, subcellular localization and predicted substrate specificity of several other PDEs indicate significant plasticity and spatial control of cyclic nucleotide signaling during the lytic cycle. Our findings shall enable a rational dissection of signaling in tachyzoites by combinatorial mutagenesis. Moreover, the phylogenetic divergence of selected Toxoplasma PDEs from human counterparts can be exploited to develop parasite-specific inhibitors and therapeutics.
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Key Words
- 3′IT, 3′-insertional tagging
- AC, adenylate cyclase
- Apicomplexa
- Bradyzoite
- COS, crossover sequence
- CRISPR, clustered regularly interspaced short palindromic repeats
- EES, entero-epithelial stages
- FPKM, fragments per kilobase of exon model per million
- GC, guanylate cyclase
- GMQE, Global Model Quality Estimation
- HFF, human foreskin fibroblast
- HXGPRT, hypoxanthine-xanthine-guanine phosphoribosyltransferase
- IMC, inner membrane complex
- Lytic cycle
- MAEBL, merozoite adhesive erythrocytic binding ligand
- MOI, multiplicity of infection
- OCRE, octamer repeat
- PDE, phosphodiesterase
- PKA, protein kinase A
- PKG, protein kinase G
- PM, plasma membrane
- QMEAN, Quality Model Energy Analysis
- Tachyzoite
- cAMP and cGMP signaling
- sgRNA, single guide RNA
- smHA, spaghetti monster-HA
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Affiliation(s)
- Kim Chi Vo
- Department of Molecular Parasitology, Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Özlem Günay-Esiyok
- Department of Molecular Parasitology, Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Nicolas Liem
- Experimental Biophysics, Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Nishith Gupta
- Department of Molecular Parasitology, Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany.,Department of Biological Sciences, Birla Institute of Technology and Science Pilani (BITS-P), Hyderabad, India
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16
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Ishizaki T, Chaiyawong N, Hakimi H, Asada M, Tachibana M, Ishino T, Yahata K, Kaneko O. A novel Plasmodium yoelii pseudokinase, PypPK1, is involved in erythrocyte invasion and exflagellation center formation. Parasitol Int 2020; 76:102056. [PMID: 31953169 DOI: 10.1016/j.parint.2020.102056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/12/2020] [Accepted: 01/13/2020] [Indexed: 11/24/2022]
Abstract
Malaria parasites proliferate by repeated invasion of and multiplication within erythrocytes in the vertebrate host. Sexually committed intraerythrocytic parasites undergo sexual stage differentiation to become gametocytes. After ingestion by the mosquito, male and female gametocytes egress from erythrocytes and fertilize within the mosquito midgut. A complex signaling pathway likely responds to environmental events to trigger gametogenesis and regulate fertilization; however, such knowledge remains limited for malaria parasites. Several pseudokinases are highly transcribed at the gametocyte stage and are possible multi-functional regulators controlling critical steps of the life cycle. Here we characterized one pseudokinase, termed PypPK1, in Plasmodium yoelii that is highly expressed in schizonts and male gametocytes. Immunofluorescence assays for parasites expressing Myc-tagged PypPK1 confirmed that PypPK1 protein is expressed in schizonts and sexual stage parasites. Transgenic ΔpPK1 parasites, in which the PypPK1 gene locus was deleted by the CRISPR/Cas9 method, showed significant growth defect and reduced virulence in mice. In the blood stage, ΔpPK1 parasites were able to egress from erythrocytes similar to wild type parasites; however, erythrocyte invasion efficacy was significantly reduced. During sexual stage development, no clear changes were seen in male and female gametocytemias as well as gametocyte egress from erythrocytes; but, the number of exflagellation centers and oocysts were significantly reduced in ΔpPK1 parasites. Taken together, PypPK1 has an important role for both erythrocyte invasion and exflagellation center formation.
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Affiliation(s)
- Takahiro Ishizaki
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
| | - Nattawat Chaiyawong
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
| | - Hassan Hakimi
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
| | - Masahito Asada
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
| | - Mayumi Tachibana
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Toon, Ehime 791-0295, Japan.
| | - Tomoko Ishino
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Toon, Ehime 791-0295, Japan.
| | - Kazuhide Yahata
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
| | - Osamu Kaneko
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
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17
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Garfoot AL, Wilson GM, Coon JJ, Knoll LJ. Proteomic and transcriptomic analyses of early and late-chronic Toxoplasma gondii infection shows novel and stage specific transcripts. BMC Genomics 2019; 20:859. [PMID: 31726967 PMCID: PMC6857164 DOI: 10.1186/s12864-019-6213-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 10/22/2019] [Indexed: 12/21/2022] Open
Abstract
Abstract
Background
The protozoan pathogen Toxoplasma gondii has the unique ability to develop a chronic infection in the brain of its host by transitioning from the fast growing tachyzoite morphology to latent bradyzoite morphology. A hallmark of the bradyzoite is the development of neuronal cysts that are resilient against host immune response and current therapeutics. The bradyzoite parasites within the cyst have a carbohydrate and protein-rich wall and a slow-replication cycle, allowing them to remain hidden from the host. The intracellular, encysted lifestyle of T. gondii has made them recalcitrant to molecular analysis in vivo.
Results
Here, we detail the results from transcriptional and proteomic analyses of bradyzoite-enriched fractions isolated from mouse brains infected with T. gondii over a time course of 21 to 150 days. The enrichment procedure afforded consistent identification of over 2000 parasitic peptides from the mixed-organism sample, representing 366 T. gondii proteins at 28, 90, and 120 day timepoints. Deep sequencing of transcripts expressed during these three timepoints revealed that a subpopulation of genes that are transcriptionally expressed at a high level. Approximately one-third of these transcripts are more enriched during bradyzoite conditions compared to tachyzoites and approximately half are expressed at similar levels during each phase. The T. gondii transcript which increased the most over the course of chronic infection, sporoAMA1, shows stage specific isoform expression of the gene.
Conclusions
We have expanded the transcriptional profile of in vivo bradyzoites to 120 days post-infection and provided the first in vivo proteomic profile of T. gondii bradyzoites. The RNA sequencing depth of in vivo bradyzoite T. gondii was over 250-fold greater than previous reports and allowed us to identify low level transcripts and a novel bradyzoite-specific isoform of sporoAMA1.
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18
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Abstract
Understanding the mechanisms behind host cell invasion by Plasmodium falciparum remains a major hurdle to developing antimalarial therapeutics that target the asexual cycle and the symptomatic stage of malaria. Host cell entry is enabled by a multitude of precisely timed and tightly regulated receptor-ligand interactions. Cyclic nucleotide signaling has been implicated in regulating parasite invasion, and an important downstream effector of the cAMP-signaling pathway is protein kinase A (PKA), a cAMP-dependent protein kinase. There is increasing evidence that P. falciparum PKA (PfPKA) is responsible for phosphorylation of the cytoplasmic domain of P. falciparum apical membrane antigen 1 (PfAMA1) at Ser610, a cAMP-dependent event that is crucial for successful parasite invasion. In the present study, CRISPR-Cas9 and conditional gene deletion (dimerizable cre) technologies were implemented to generate a P. falciparum parasite line in which expression of the catalytic subunit of PfPKA (PfPKAc) is under conditional control, demonstrating highly efficient dimerizable Cre recombinase (DiCre)-mediated gene excision and complete knockdown of protein expression. Parasites lacking PfPKAc show severely reduced growth after one intraerythrocytic growth cycle and are deficient in host cell invasion, as highlighted by live-imaging experiments. Furthermore, PfPKAc-deficient parasites are unable to phosphorylate PfAMA1 at Ser610. This work not only identifies an essential role for PfPKAc in the P. falciparum asexual life cycle but also confirms that PfPKAc is the kinase responsible for phosphorylating PfAMA1 Ser610.IMPORTANCE Malaria continues to present a major global health burden, particularly in low-resource countries. Plasmodium falciparum, the parasite responsible for the most severe form of malaria, causes disease through rapid and repeated rounds of invasion and replication within red blood cells. Invasion into red blood cells is essential for P. falciparum survival, and the molecular events mediating this process have gained much attention as potential therapeutic targets. With no effective vaccine available, and with the emergence of resistance to antimalarials, there is an urgent need for the development of new therapeutics. Our research has used genetic techniques to provide evidence of an essential protein kinase involved in P. falciparum invasion. Our work adds to the current understanding of parasite signaling processes required for invasion, highlighting PKA as a potential drug target to inhibit invasion for the treatment of malaria.
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19
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Gilson PR, Kumarasingha R, Thompson J, Zhang X, Penington JS, Kalhor R, Bullen HE, Lehane AM, Dans MG, de Koning-Ward TF, Holien JK, Soares da Costa TP, Hulett MD, Buskes MJ, Crabb BS, Kirk K, Papenfuss AT, Cowman AF, Abbott BM. A 4-cyano-3-methylisoquinoline inhibitor of Plasmodium falciparum growth targets the sodium efflux pump PfATP4. Sci Rep 2019; 9:10292. [PMID: 31311978 PMCID: PMC6635429 DOI: 10.1038/s41598-019-46500-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 06/28/2019] [Indexed: 12/31/2022] Open
Abstract
We developed a novel series of antimalarial compounds based on a 4-cyano-3-methylisoquinoline. Our lead compound MB14 achieved modest inhibition of the growth in vitro of the human malaria parasite, Plasmodium falciparum. To identify its biological target we selected for parasites resistant to MB14. Genome sequencing revealed that all resistant parasites bore a single point S374R mutation in the sodium (Na+) efflux transporter PfATP4. There are many compounds known to inhibit PfATP4 and some are under preclinical development. MB14 was shown to inhibit Na+ dependent ATPase activity in parasite membranes, consistent with the compound targeting PfATP4 directly. PfATP4 inhibitors cause swelling and lysis of infected erythrocytes, attributed to the accumulation of Na+ inside the intracellular parasites and the resultant parasite swelling. We show here that inhibitor-induced lysis of infected erythrocytes is dependent upon the parasite protein RhopH2, a component of the new permeability pathways that are induced by the parasite in the erythrocyte membrane. These pathways mediate the influx of Na+ into the infected erythrocyte and their suppression via RhopH2 knockdown limits the accumulation of Na+ within the parasite hence protecting the infected erythrocyte from lysis. This study reveals a role for the parasite-induced new permeability pathways in the mechanism of action of PfATP4 inhibitors.
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Affiliation(s)
- Paul R Gilson
- Burnet Institute, Melbourne, Victoria, 3004, Australia. .,Monash University, Melbourne, Victoria, 3800, Australia.
| | | | - Jennifer Thompson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia
| | - Xinxin Zhang
- Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | | | - Robabeh Kalhor
- La Trobe University, Melbourne, Victoria, 3086, Australia
| | | | - Adele M Lehane
- Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Madeline G Dans
- Burnet Institute, Melbourne, Victoria, 3004, Australia.,School of Medicine, Deakin University, Waurn Ponds, Victoria, 3216, Australia
| | | | - Jessica K Holien
- St. Vincent's Institute of Medical Research, Melbourne, Victoria, 3065, Australia
| | | | - Mark D Hulett
- La Trobe University, Melbourne, Victoria, 3086, Australia
| | | | - Brendan S Crabb
- Burnet Institute, Melbourne, Victoria, 3004, Australia.,Monash University, Melbourne, Victoria, 3800, Australia.,University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Anthony T Papenfuss
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia.,University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Alan F Cowman
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia.,University of Melbourne, Melbourne, Victoria, 3010, Australia
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20
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Patel A, Perrin AJ, Flynn HR, Bisson C, Withers-Martinez C, Treeck M, Flueck C, Nicastro G, Martin SR, Ramos A, Gilberger TW, Snijders AP, Blackman MJ, Baker DA. Cyclic AMP signalling controls key components of malaria parasite host cell invasion machinery. PLoS Biol 2019; 17:e3000264. [PMID: 31075098 PMCID: PMC6530879 DOI: 10.1371/journal.pbio.3000264] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 05/22/2019] [Accepted: 04/26/2019] [Indexed: 01/01/2023] Open
Abstract
Cyclic AMP (cAMP) is an important signalling molecule across evolution, but its role in malaria parasites is poorly understood. We have investigated the role of cAMP in asexual blood stage development of Plasmodium falciparum through conditional disruption of adenylyl cyclase beta (ACβ) and its downstream effector, cAMP-dependent protein kinase (PKA). We show that both production of cAMP and activity of PKA are critical for erythrocyte invasion, whilst key developmental steps that precede invasion still take place in the absence of cAMP-dependent signalling. We also show that another parasite protein with putative cyclic nucleotide binding sites, Plasmodium falciparum EPAC (PfEpac), does not play an essential role in blood stages. We identify and quantify numerous sites, phosphorylation of which is dependent on cAMP signalling, and we provide mechanistic insight as to how cAMP-dependent phosphorylation of the cytoplasmic domain of the essential invasion adhesin apical membrane antigen 1 (AMA1) regulates erythrocyte invasion.
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Affiliation(s)
- Avnish Patel
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Abigail J. Perrin
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Helen R. Flynn
- Mass Spectrometry Proteomics Platform, The Francis Crick Institute, London, United Kingdom
| | - Claudine Bisson
- Crystallography, Institute of Structural and Molecular Biology, Birkbeck College, London, United Kingdom
| | | | - Moritz Treeck
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Christian Flueck
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Giuseppe Nicastro
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Stephen R. Martin
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Andres Ramos
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Tim W. Gilberger
- Bernhard-Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Ambrosius P. Snijders
- Mass Spectrometry Proteomics Platform, The Francis Crick Institute, London, United Kingdom
| | - Michael J. Blackman
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom
| | - David A. Baker
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
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21
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Masch A, Nasereddin A, Alder A, Bird MJ, Schweda SI, Preu L, Doerig C, Dzikowski R, Gilberger TW, Kunick C. Structure-activity relationships in a series of antiplasmodial thieno[2,3-b]pyridines. Malar J 2019; 18:89. [PMID: 30898128 PMCID: PMC6429710 DOI: 10.1186/s12936-019-2725-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/12/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is one of the most prevalent tropical infectious diseases. Since recently cases of artemisinin resistance were reported, novel anti-malarial drugs are required which differ from artemisinins in structure and biological target. The plasmodial glycogen synthase kinase-3 (PfGSK-3) was suggested as a new anti-malarial drug target. 4-Phenylthieno[2,3-b]pyridines were previously identified as selective PfGSK-3 inhibitors with antiplasmodial activity. The present study aims at identifying a molecular position on this scaffold for the attachment of side chains in order to improve solubility and antiplasmodial activity. Furthermore, the role of axial chirality in the compound class for antiplasmodial activity and PfGSK-3 inhibition was investigated. METHODS 4-Phenylthieno[2,3-b]pyridines with substituents in 4-position of the phenyl ring were docked into the ATP binding site of PfGSK-3. The compounds were synthesized employing a Thorpe reaction as final step. The enantiomers of one congener were separated by chiral HPLC. All derivatives were tested for inhibition of asexual erythrocytic stages of transgenic NF54-luc Plasmodium falciparum. Selected compounds with promising antiplasmodial activity were further evaluated for inhibition of HEK293 cells as well as inhibition of isolated PfGSK-3 and HsGSK-3. The kinetic aqueous solubility was assessed by laser nephelometry. RESULTS The para position at the 4-phenyl ring of the title compounds was identified as a suitable point for the attachment of side chains. While alkoxy substituents in this position led to decreased antiplasmodial activity, alkylamino groups retained antiparasitic potency. The most promising of these congeners (4h) was investigated in detail. This compound is a selective PfGSK-3 inhibitor (versus the human GSK-3 orthologue), and exhibits improved antiplasmodial activity in vitro as well as better solubility in aqueous media than its unsubstituted parent structure. The derivative 4b was separated into the atropisomers, and it was shown that the (+)-enantiomer acts as eutomer. CONCLUSIONS The attachment of alkylamino side chains leads to the improvement of antiplasmodial activity and aqueous solubility of selective PfGSK-inhibitors belonging to the class of 4-phenylthieno[2,3-b]pyridines. These molecules show axial chirality, a feature of high impact for biological activity. The findings can be exploited for the development of improved selective PfGSK-3 inhibitors.
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Affiliation(s)
- Andreas Masch
- Institut für Medizinische und Pharmazeutische Chemie, Technische Universität Braunschweig, Beethovenstraße 55, 38106, Braunschweig, Germany
| | - Abed Nasereddin
- Department of Microbiology and Molecular Genetics, IMRIC, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, 91120, Jerusalem, Israel.,Genomics Applications Laboratory, Core Research Facility, Faculty of Medicine, The Hebrew University-Hadassah Medical School, 91120, Jerusalem, Israel
| | - Arne Alder
- Centre for Structural Systems Biology, Deutsches Elektronen-Synchrotron, Notkestraße 85, 22607, Hamburg, Germany.,Bernhard-Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany
| | - Megan J Bird
- Biomedicine Discovery Institute, Infection & Immunity Program, Department of Microbiology, Monash University, Clayton, VIC, 3800, Australia
| | - Sandra I Schweda
- Institut für Medizinische und Pharmazeutische Chemie, Technische Universität Braunschweig, Beethovenstraße 55, 38106, Braunschweig, Germany.,Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Franz-Liszt-Straße 35A, 38106, Braunschweig, Germany
| | - Lutz Preu
- Institut für Medizinische und Pharmazeutische Chemie, Technische Universität Braunschweig, Beethovenstraße 55, 38106, Braunschweig, Germany
| | - Christian Doerig
- Biomedicine Discovery Institute, Infection & Immunity Program, Department of Microbiology, Monash University, Clayton, VIC, 3800, Australia.,Centre for Chronic, Inflammatory and Infectious Diseases, School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC, 3083, Australia
| | - Ron Dzikowski
- Department of Microbiology and Molecular Genetics, IMRIC, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, 91120, Jerusalem, Israel
| | - Tim W Gilberger
- Centre for Structural Systems Biology, Deutsches Elektronen-Synchrotron, Notkestraße 85, 22607, Hamburg, Germany.,Bernhard-Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359, Hamburg, Germany
| | - Conrad Kunick
- Institut für Medizinische und Pharmazeutische Chemie, Technische Universität Braunschweig, Beethovenstraße 55, 38106, Braunschweig, Germany. .,Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig, Franz-Liszt-Straße 35A, 38106, Braunschweig, Germany.
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Flueck C, Drought LG, Jones A, Patel A, Perrin AJ, Walker EM, Nofal SD, Snijders AP, Blackman MJ, Baker DA. Phosphodiesterase beta is the master regulator of cAMP signalling during malaria parasite invasion. PLoS Biol 2019; 17:e3000154. [PMID: 30794532 PMCID: PMC6402698 DOI: 10.1371/journal.pbio.3000154] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 03/06/2019] [Accepted: 02/05/2019] [Indexed: 12/29/2022] Open
Abstract
Cyclic nucleotide signalling is a major regulator of malaria parasite differentiation. Phosphodiesterase (PDE) enzymes are known to control cyclic GMP (cGMP) levels in the parasite, but the mechanisms by which cyclic AMP (cAMP) is regulated remain enigmatic. Here, we demonstrate that Plasmodium falciparum phosphodiesterase β (PDEβ) hydrolyses both cAMP and cGMP and is essential for blood stage viability. Conditional gene disruption causes a profound reduction in invasion of erythrocytes and rapid death of those merozoites that invade. We show that this dual phenotype results from elevated cAMP levels and hyperactivation of the cAMP-dependent protein kinase (PKA). Phosphoproteomic analysis of PDEβ-null parasites reveals a >2-fold increase in phosphorylation at over 200 phosphosites, more than half of which conform to a PKA substrate consensus sequence. We conclude that PDEβ plays a critical role in governing correct temporal activation of PKA required for erythrocyte invasion, whilst suppressing untimely PKA activation during early intra-erythrocytic development.
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Affiliation(s)
- Christian Flueck
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Laura G. Drought
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Andrew Jones
- Protein Analysis and Proteomics Laboratory, the Francis Crick Institute, London, United Kingdom
| | - Avnish Patel
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Abigail J. Perrin
- Malaria Biochemistry Laboratory, the Francis Crick Institute, London, United Kingdom
| | - Eloise M. Walker
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Stephanie D. Nofal
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Ambrosius P. Snijders
- Protein Analysis and Proteomics Laboratory, the Francis Crick Institute, London, United Kingdom
| | - Michael J. Blackman
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Malaria Biochemistry Laboratory, the Francis Crick Institute, London, United Kingdom
| | - David A. Baker
- Faculty of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
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23
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Baker DA, Drought LG, Flueck C, Nofal SD, Patel A, Penzo M, Walker EM. Cyclic nucleotide signalling in malaria parasites. Open Biol 2018; 7:rsob.170213. [PMID: 29263246 PMCID: PMC5746546 DOI: 10.1098/rsob.170213] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/28/2017] [Indexed: 12/22/2022] Open
Abstract
The cyclic nucleotides 3′, 5′-cyclic adenosine monophosphate (cAMP) and 3′, 5′-cyclic guanosine monophosphate (cGMP) are intracellular messengers found in most animal cell types. They usually mediate an extracellular stimulus to drive a change in cell function through activation of their respective cyclic nucleotide-dependent protein kinases, PKA and PKG. The enzymatic components of the malaria parasite cyclic nucleotide signalling pathways have been identified, and the genetic and biochemical studies of these enzymes carried out to date are reviewed herein. What has become very clear is that cyclic nucleotides play vital roles in controlling every stage of the complex malaria parasite life cycle. Our understanding of the involvement of cyclic nucleotide signalling in orchestrating the complex biology of malaria parasites is still in its infancy, but the recent advances in our genetic tools and the increasing interest in signalling will deliver more rapid progress in the coming years.
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Affiliation(s)
- David A Baker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Laura G Drought
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Christian Flueck
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Stephanie D Nofal
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Avnish Patel
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Maria Penzo
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK.,Tres Cantos Medicines Development Campus, Diseases of the Developing World, GlaxoSmithKline, Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Eloise M Walker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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24
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Abstract
Plasmodium species cause malaria by proliferating in human erythrocytes. Invasion of immunologically privileged erythrocytes provides a relatively protective niche as well as access to a rich source of nutrients. Plasmodium spp. target erythrocytes of different ages, but share a common mechanism of invasion. Specific engagement of erythrocyte receptors defines target cell tropism, activating downstream events and resulting in the physical penetration of the erythrocyte, powered by the parasite's actinomyosin-based motor. Here we review the latest in our understanding of the molecular composition of this highly complex and fascinating biological process.
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25
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Kumar K, Srinivasan P, Nold MJ, Moch JK, Reiter K, Sturdevant D, Otto TD, Squires RB, Herrera R, Nagarajan V, Rayner JC, Porcella SF, Geromanos SJ, Haynes JD, Narum DL. Profiling invasive Plasmodium falciparum merozoites using an integrated omics approach. Sci Rep 2017; 7:17146. [PMID: 29215067 PMCID: PMC5719419 DOI: 10.1038/s41598-017-17505-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/22/2017] [Indexed: 02/06/2023] Open
Abstract
The symptoms of malaria are brought about by blood-stage parasites, which are established when merozoites invade human erythrocytes. Our understanding of the molecular events that underpin erythrocyte invasion remains hampered by the short-period of time that merozoites are invasive. To address this challenge, a Plasmodium falciparum gamma-irradiated long-lived merozoite (LLM) line was developed and investigated. Purified LLMs invaded erythrocytes by an increase of 10–300 fold compared to wild-type (WT) merozoites. Using an integrated omics approach, we investigated the basis for the phenotypic difference. Only a few single nucleotide polymorphisms within the P. falciparum genome were identified and only marginal differences were observed in the merozoite transcriptomes. By contrast, using label-free quantitative mass-spectrometry, a significant change in protein abundance was noted, of which 200 were proteins of unknown function. We determined the relative molar abundance of over 1100 proteins in LLMs and further characterized the major merozoite surface protein complex. A unique processed MSP1 intermediate was identified in LLM but not observed in WT suggesting that delayed processing may be important for the observed phenotype. This integrated approach has demonstrated the significant role of the merozoite proteome during erythrocyte invasion, while identifying numerous unknown proteins likely to be involved in invasion.
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Affiliation(s)
- Krishan Kumar
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Rockville, MD, USA
| | - Prakash Srinivasan
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA. .,Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
| | | | - J Kathleen Moch
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Karine Reiter
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Rockville, MD, USA
| | - Dan Sturdevant
- Genomics Unit, Research Technologies Section, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT, USA
| | - Thomas D Otto
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - R Burke Squires
- Computational Biology Section, Bioinformatics and Computational Biosciences Branch, NIAID, NIH, Bethesda, MD, USA
| | - Raul Herrera
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Rockville, MD, USA
| | - Vijayaraj Nagarajan
- Computational Biology Section, Bioinformatics and Computational Biosciences Branch, NIAID, NIH, Bethesda, MD, USA
| | - Julian C Rayner
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - Stephen F Porcella
- Genomics Unit, Research Technologies Section, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT, USA
| | | | - J David Haynes
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - David L Narum
- Laboratory of Malaria Immunology and Vaccinology, NIAID, NIH, Rockville, MD, USA.
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26
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Molecular mechanisms that mediate invasion and egress of malaria parasites from red blood cells. Curr Opin Hematol 2017; 24:208-214. [PMID: 28306665 DOI: 10.1097/moh.0000000000000334] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW Malaria parasites invade and multiply in diverse host cells during their complex life cycle. Some blood stage parasites transform into male and female gametocytes that are transmitted by female anopheline mosquitoes. The gametocytes are activated in the mosquito midgut to form male and female gametes, which egress from RBCs to mate and form a zygote. Here, we will review our current understanding of the molecular mechanisms that mediate invasion and egress by malaria parasites at different life cycle stages. RECENT FINDINGS A number of key effector molecules such as parasite protein ligands for receptor-engagement during invasion as well as proteases and perforin-like proteins that mediate egress have been identified. Interestingly, these parasite-encoded effectors are located in internal, vesicular organelles and are secreted in a highly regulated manner during invasion and egress. Here, we will review our current understanding of the functional roles of these effectors as well as the signaling pathways that regulate their timely secretion with accurate spatiotemporal coordinates. SUMMARY Understanding the molecular basis of key processes such as host cell invasion and egress by malaria parasites could provide novel targets for development of inhibitors to block parasite growth and transmission.
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Designed synthesis of a "One for Two" hydrophilic magnetic amino-functionalized metal-organic framework for highly efficient enrichment of glycopeptides and phosphopeptides. Sci Rep 2017; 7:1162. [PMID: 28442774 PMCID: PMC5430903 DOI: 10.1038/s41598-017-01341-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 03/28/2017] [Indexed: 12/18/2022] Open
Abstract
Highly efficient enrichment of glycopeptides or phosphopeptides from complex biological samples is indispensable for high-throughput mass spectrometry analysis. In this study, for the first time, a "one for two" hydrophilic magnetic amino-functionalized metal-organic framework (MOF) was designed and synthesized for selective enrichment of both glycopeptides and phosphopeptides. A well-known solvo-thermal reaction was adopted to prepare a magnetic core Fe3O4, followed by self- polymerization of dopamine, creating a polydopamine (PDA) onto Fe3O4. Thanks to the hydroxyl and amino group of PDA, Zr3+ was easily adhered to the surface, inducing the following one-pot MOF reaction with amino ligand. After characterization of the as-prepared MOFs (denoted as Fe3O4@PDA@UiO-66-NH2), its ultrahigh surface area, excellent hydrophilicity and strong magnetic responsiveness were highly confirmed. Based on hydrophilic interaction, it was applied to glycopeptide enrichment, while based on strong binding between Zr and phosphopeptides, it was applied to phosphopeptide enrichment, both exhibiting excellent performance in standard proteins and human serum with high sensitivity and selectivity. These results showed the as-prepared MOFs had great potential in proteomics research.
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28
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Plasmodium falciparum erythrocyte-binding antigen 175 triggers a biophysical change in the red blood cell that facilitates invasion. Proc Natl Acad Sci U S A 2017; 114:4225-4230. [PMID: 28373555 DOI: 10.1073/pnas.1620843114] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Invasion of the red blood cell (RBC) by the Plasmodium parasite defines the start of malaria disease pathogenesis. To date, experimental investigations into invasion have focused predominantly on the role of parasite adhesins or signaling pathways and the identity of binding receptors on the red cell surface. A potential role for signaling pathways within the erythrocyte, which might alter red cell biophysical properties to facilitate invasion, has largely been ignored. The parasite erythrocyte-binding antigen 175 (EBA175), a protein required for entry in most parasite strains, plays a key role by binding to glycophorin A (GPA) on the red cell surface, although the function of this binding interaction is unknown. Here, using real-time deformability cytometry and flicker spectroscopy to define biophysical properties of the erythrocyte, we show that EBA175 binding to GPA leads to an increase in the cytoskeletal tension of the red cell and a reduction in the bending modulus of the cell's membrane. We isolate the changes in the cytoskeleton and membrane and show that reduction in the bending modulus is directly correlated with parasite invasion efficiency. These data strongly imply that the malaria parasite primes the erythrocyte surface through its binding antigens, altering the biophysical nature of the target cell and thus reducing a critical energy barrier to invasion. This finding would constitute a major change in our concept of malaria parasite invasion, suggesting it is, in fact, a balance between parasite and host cell physical forces working together to facilitate entry.
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