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Hsp90 and Associated Co-Chaperones of the Malaria Parasite. Biomolecules 2022; 12:biom12081018. [PMID: 35892329 PMCID: PMC9332011 DOI: 10.3390/biom12081018] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 07/16/2022] [Accepted: 07/17/2022] [Indexed: 12/14/2022] Open
Abstract
Heat shock protein 90 (Hsp90) is one of the major guardians of cellular protein homeostasis, through its specialized molecular chaperone properties. While Hsp90 has been extensively studied in many prokaryotic and higher eukaryotic model organisms, its structural, functional, and biological properties in parasitic protozoans are less well defined. Hsp90 collaborates with a wide range of co-chaperones that fine-tune its protein folding pathway. Co-chaperones play many roles in the regulation of Hsp90, including selective targeting of client proteins, and the modulation of its ATPase activity, conformational changes, and post-translational modifications. Plasmodium falciparum is responsible for the most lethal form of human malaria. The survival of the malaria parasite inside the host and the vector depends on the action of molecular chaperones. The major cytosolic P. falciparum Hsp90 (PfHsp90) is known to play an essential role in the development of the parasite, particularly during the intra-erythrocytic stage in the human host. Although PfHsp90 shares significant sequence and structural similarity with human Hsp90, it has several major structural and functional differences. Furthermore, its co-chaperone network appears to be substantially different to that of the human host, with the potential absence of a key homolog. Indeed, PfHsp90 and its interface with co-chaperones represent potential drug targets for antimalarial drug discovery. In this review, we critically summarize the current understanding of the properties of Hsp90, and the associated co-chaperones of the malaria parasite.
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Fréville A, Gnangnon B, Khelifa AS, Gissot M, Khalife J, Pierrot C. Deciphering the Role of Protein Phosphatases in Apicomplexa: The Future of Innovative Therapeutics? Microorganisms 2022; 10:microorganisms10030585. [PMID: 35336160 PMCID: PMC8949495 DOI: 10.3390/microorganisms10030585] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/04/2022] [Accepted: 03/05/2022] [Indexed: 12/10/2022] Open
Abstract
Parasites belonging to the Apicomplexa phylum still represent a major public health and world-wide socioeconomic burden that is greatly amplified by the spread of resistances against known therapeutic drugs. Therefore, it is essential to provide the scientific and medical communities with innovative strategies specifically targeting these organisms. In this review, we present an overview of the diversity of the phosphatome as well as the variety of functions that phosphatases display throughout the Apicomplexan parasites’ life cycles. We also discuss how this diversity could be used for the design of innovative and specific new drugs/therapeutic strategies.
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Affiliation(s)
- Aline Fréville
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Centre d’Infection et d’Immunité de Lille, 59000 Lille, France; (B.G.); (A.S.K.); (M.G.); (J.K.)
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Tropical Medicine and Hygiene, Keppel Street, London WC1E 7HT, UK
- Correspondence: (A.F.); (C.P.)
| | - Bénédicte Gnangnon
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Centre d’Infection et d’Immunité de Lille, 59000 Lille, France; (B.G.); (A.S.K.); (M.G.); (J.K.)
- Department of Epidemiology, Center for Communicable Diseases Dynamics, Harvard TH Chan School of Public Health, Boston, MA 02115, USA
| | - Asma S. Khelifa
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Centre d’Infection et d’Immunité de Lille, 59000 Lille, France; (B.G.); (A.S.K.); (M.G.); (J.K.)
| | - Mathieu Gissot
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Centre d’Infection et d’Immunité de Lille, 59000 Lille, France; (B.G.); (A.S.K.); (M.G.); (J.K.)
| | - Jamal Khalife
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Centre d’Infection et d’Immunité de Lille, 59000 Lille, France; (B.G.); (A.S.K.); (M.G.); (J.K.)
| | - Christine Pierrot
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Centre d’Infection et d’Immunité de Lille, 59000 Lille, France; (B.G.); (A.S.K.); (M.G.); (J.K.)
- Correspondence: (A.F.); (C.P.)
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Stofberg ML, Caillet C, de Villiers M, Zininga T. Inhibitors of the Plasmodium falciparum Hsp90 towards Selective Antimalarial Drug Design: The Past, Present and Future. Cells 2021; 10:2849. [PMID: 34831072 PMCID: PMC8616389 DOI: 10.3390/cells10112849] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 12/12/2022] Open
Abstract
Malaria is still one of the major killer parasitic diseases in tropical settings, posing a public health threat. The development of antimalarial drug resistance is reversing the gains made in attempts to control the disease. The parasite leads a complex life cycle that has adapted to outwit almost all known antimalarial drugs to date, including the first line of treatment, artesunate. There is a high unmet need to develop new strategies and identify novel therapeutics to reverse antimalarial drug resistance development. Among the strategies, here we focus and discuss the merits of the development of antimalarials targeting the Heat shock protein 90 (Hsp90) due to the central role it plays in protein quality control.
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Affiliation(s)
| | | | | | - Tawanda Zininga
- Department of Biochemistry, Stellenbosch University, Stellenbosch 7600, South Africa; (M.L.S.); (C.C.); (M.d.V.)
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Zhu X, Sun L, He Y, Wei H, Hong M, Liu F, Liu Q, Cao Y, Cui L. Plasmodium berghei serine/threonine protein phosphatase PP5 plays a critical role in male gamete fertility. Int J Parasitol 2019; 49:685-695. [DOI: 10.1016/j.ijpara.2019.03.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Accepted: 03/18/2019] [Indexed: 02/06/2023]
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Noack S, Chapman HD, Selzer PM. Anticoccidial drugs of the livestock industry. Parasitol Res 2019; 118:2009-2026. [PMID: 31152233 PMCID: PMC6611755 DOI: 10.1007/s00436-019-06343-5] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 04/29/2019] [Indexed: 12/11/2022]
Abstract
Coccidiosis is a parasitic disease of a wide variety of animals caused by coccidian protozoa. The coccidia are responsible for major economic losses of the livestock industry. For example, the annual cost due to coccidiosis to the global poultry industry has been estimated to exceed US$ 3 billion annually. Currently available drugs for the control of this disease are either polyether ionophorous antibiotics that are derived from fermentation products, or synthetic compounds, produced by chemical synthesis. Unfortunately, no new drugs in either category have been approved for use for decades. Resistance has been documented for all those of the drugs currently employed and therefore the discovery of novel drugs with unique modes of action is imperative if chemotherapy is to remain the principal means to control this disease. This chapter aims to give an overview of the efficacy and mode of action of the current compounds used to control coccidiosis in livestock and provides a brief outlook of research needs for the future.
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Affiliation(s)
- Sandra Noack
- Boehringer Ingelheim Vetmedica GmbH, Ingelheim am Rhein, Germany
| | - H David Chapman
- Department of Poultry Science, University of Arkansas, Fayetteville, AR, USA
| | - Paul M Selzer
- Boehringer Ingelheim Vetmedica GmbH, Ingelheim am Rhein, Germany.
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Yang C, Arrizabalaga G. The serine/threonine phosphatases of apicomplexan parasites. Mol Microbiol 2017; 106:1-21. [PMID: 28556455 DOI: 10.1111/mmi.13715] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2017] [Indexed: 12/21/2022]
Abstract
The balance between phosphorylation and de-phosphorylation, which is delicately regulated by protein kinases and phosphatases, is critical for nearly all biological processes. The Apicomplexa are a large phylum which contains various parasitic protists, including human pathogens, such as Plasmodium, Toxoplasma, Cryptosporidium and Babesia species. The diverse life cycles of these parasites are highly complex and, not surprisingly, many of their key steps are exquisitely regulated by phosphorylation. Interestingly, many of the kinases and phosphatases, as well as the substrates involved in these events are unique to the parasites and therefore phosphorylation constitutes a viable target for antiparasitic intervention. Most progress on this realm has come from studies in Toxoplasma and Plasmodium of their respective kinomes and phosphoproteomes. Nonetheless, given their likely importance, phosphatases have recently become the focus of research within the apicomplexan parasites. In this review, we concentrate on serine/threonine phosphatases in apicomplexan parasites, with the focus on comprehensively identifying and naming protein phosphatases in available apicomplexan genomes, and summarizing the progress of their functional analyses in recent years.
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Affiliation(s)
- Chunlin Yang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Gustavo Arrizabalaga
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, USA
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Okombo J, Chibale K. Antiplasmodial drug targets: a patent review (2000 – 2013). Expert Opin Ther Pat 2015; 26:107-30. [DOI: 10.1517/13543776.2016.1113258] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Gupta S, Jadaun A, Kumar H, Raj U, Varadwaj PK, Rao A. Exploration of new drug-like inhibitors for serine/threonine protein phosphatase 5 ofPlasmodium falciparum: a docking and simulation study. J Biomol Struct Dyn 2015; 33:2421-41. [DOI: 10.1080/07391102.2015.1051114] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Pandey R, Mohmmed A, Pierrot C, Khalife J, Malhotra P, Gupta D. Genome wide in silico analysis of Plasmodium falciparum phosphatome. BMC Genomics 2014; 15:1024. [PMID: 25425018 PMCID: PMC4256932 DOI: 10.1186/1471-2164-15-1024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 11/12/2014] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Eukaryotic cellular machineries are intricately regulated by several molecular mechanisms involving transcriptional control, post-translational control and post-translational modifications of proteins (PTMs). Reversible protein phosphorylation/dephosphorylation process, which involves kinases as well as phosphatases, represents an important regulatory mechanism for diverse pathways and systems in all organisms including human malaria parasite, Plasmodium falciparum. Earlier analysis on P. falciparum protein-phosphatome revealed presence of 34 phosphatases in Plasmodium genome. Recently, we re-analysed P. falciparum phosphatome aimed at identifying parasite specific phosphatases. RESULTS Plasmodium database (PlasmoDB 9.2) search, combined with PFAM and CDD searches, revealed 67 candidate phosphatases in P. falciparum. While this number is far less than the number of phosphatases present in Homo sapiens, it is almost the same as in other Plasmodium species. These Plasmodium phosphatase proteins were classified into 13 super families based on NCBI CDD search. Analysis of proteins expression profiles of the 67 phosphatases revealed that 44 phosphatases are expressed in both schizont as well as gametocytes stages. Fourteen phosphatases are common in schizont, ring and trophozoite stages, four phosphatases are restricted to gametocytes, whereas another three restricted to schizont stage. The phylogenetic trees for each of the known phosphatase super families reveal a considerable phylogenetic closeness amongst apicomplexan organisms and a considerable phylogenetic distance with other eukaryotic model organisms included in the study. The GO assignments and predicted interaction partners of the parasite phosphatases indicate its important role in diverse cellular processes. CONCLUSION In the study presented here, we reviewed the P. falciparum phosphatome to show presence of 67 candidate phosphatases in P. falciparum genomes/proteomes. Intriguingly, amongst these phosphatases, we could identify six Plasmodium specific phosphatases and 33 putative phosphatases that do not have human orthologs, thereby suggesting that these phosphatases have the potential to be explored as novel antimalarial drug targets.
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Affiliation(s)
| | | | | | - Jamal Khalife
- Structural and Computational Biology group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India.
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Chen X, Lü S, Zhang Y. Characterization of protein phosphatase 5 from three lepidopteran insects: Helicoverpa armigera, Mythimna separata and Plutella xylostella. PLoS One 2014; 9:e97437. [PMID: 24823652 PMCID: PMC4019573 DOI: 10.1371/journal.pone.0097437] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 04/17/2014] [Indexed: 11/18/2022] Open
Abstract
Protein phosphatase 5 (PP5), a unique member of serine/threonine phosphatases, regulates a variety of biological processes. We obtained full-length PP5 cDNAs from three lepidopteran insects, Helicoverpa armigera, Mythimna separata and Plutella xylostella, encoding predicted proteins of 490 (55.98 kDa), 490 (55.82 kDa) and 491 (56.07 kDa) amino acids, respectively. These sequences shared a high identity with other insect PP5s and contained the TPR (tetratricopeptide repeat) domains at N-terminal regions and highly conserved C-terminal catalytic domains. Tissue- and stage-specific expression pattern analyses revealed these three PP5 genes were constitutively expressed in all stages and in tested tissues with predominant transcription occurring at the egg and adult stages. Activities of Escherichia coli-produced recombinant PP5 proteins could be enhanced by almost 2-fold by a known PP5 activator: arachidonic acid. Kinetic parameters of three recombinant proteins against substrate pNPP were similar both in the absence or presence of arachidonic acid. Protein phosphatases inhibitors, okadaic acid, cantharidin, and endothall strongly impeded the activities of the three recombinant PP5 proteins, as well as exerted an inhibitory effect on crude protein phosphatases extractions from these three insects. In summary, lepidopteran PP5s share similar characteristics and are all sensitive to the protein phosphatases inhibitors. Our results also imply protein phosphatase inhibitors might be used in the management of lepidopteran pests.
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Affiliation(s)
- Xi’en Chen
- Key Laboratory of Plant Protection Resources & Pest Management of the Ministry of Education, Northwest A&F University, Yangling, Shaanxi, China
| | - Shumin Lü
- Key Laboratory of Plant Protection Resources & Pest Management of the Ministry of Education, Northwest A&F University, Yangling, Shaanxi, China
| | - Yalin Zhang
- Key Laboratory of Plant Protection Resources & Pest Management of the Ministry of Education, Northwest A&F University, Yangling, Shaanxi, China
- * E-mail:
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PhosphoTyrosyl phosphatase activator of Plasmodium falciparum: identification of its residues involved in binding to and activation of PP2A. Int J Mol Sci 2014; 15:2431-53. [PMID: 24521882 PMCID: PMC3958860 DOI: 10.3390/ijms15022431] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/10/2014] [Accepted: 01/22/2014] [Indexed: 12/13/2022] Open
Abstract
In Plasmodium falciparum (Pf), the causative agent of the deadliest form of malaria, a tight regulation of phosphatase activity is crucial for the development of the parasite. In this study, we have identified and characterized PfPTPA homologous to PhosphoTyrosyl Phosphatase Activator, an activator of protein phosphatase 2A which is a major phosphatase involved in many biological processes in eukaryotic cells. The PfPTPA sequence analysis revealed that five out of six amino acids involved in interaction with PP2A in human are conserved in P. falciparum. Localization studies showed that PfPTPA and PfPP2A are present in the same compartment of blood stage parasites, suggesting a possible interaction of both proteins. In vitro binding and functional studies revealed that PfPTPA binds to and activates PP2A. Mutation studies showed that three residues (V283, G292 and M296) of PfPTPA are indispensable for the interaction and that the G292 residue is essential for its activity. In P. falciparum, genetic studies suggested the essentiality of PfPTPA for the completion of intraerythrocytic parasite lifecycle. Using Xenopus oocytes, we showed that PfPTPA blocked the G2/M transition. Taken together, our data suggest that PfPTPA could play a role in the regulation of the P. falciparum cell cycle through its PfPP2A regulatory activity.
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Chen X, Lü S, Zhang Y. Identification and biochemical characterization of protein phosphatase 5 from the cantharidin-producing blister beetle, Epicauta chinensis. Int J Mol Sci 2013; 14:24501-13. [PMID: 24351830 PMCID: PMC3876124 DOI: 10.3390/ijms141224501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 12/09/2013] [Accepted: 12/11/2013] [Indexed: 11/16/2022] Open
Abstract
Protein phosphatase 5 (PP5) is a unique member of serine/threonine phosphatases which has been recognized in regulation of diverse cellular processes. A cDNA fragment encoding PP5 (EcPP5) was cloned and characterized from the cantharidin-producing blister beetle, E. chinensis. EcPP5 contains an open reading frame of 1500 bp that encodes a protein of 56.89 kDa. The deduced amino acid sequence shares 88% and 68% identities to the PP5 of Tribolium castaneum and humans, respectively. Analysis of the primary sequence shows that EcPP5 has three TPR (tetratricopeptide repeat) motifs at its N-terminal region and contains a highly conserved C-terminal catalytic domain. RT-PCR reveals that EcPP5 is expressed in all developmental stages and in different tissues. The recombinant EcPP5 (rEcPP5) was produced in Escherichia coli and purified to homogeneity. The purified protein exhibited phosphatase activity towards pNPP (p-nitrophenyl phosphate) and phosphopeptides, and its activity can be enhanced by arachidonic acid. In vitro inhibition study revealed that protein phosphatase inhibitors, okadaic acid, cantharidin, norcantharidin and endothall, inhibited its activity. Further, protein phosphatase activity of total soluble protein extract from E. chinensis adults could be impeded by these inhibitors suggesting there might be some mechanism to protect this beetle from being damaged by its self-produced cantharidin.
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Affiliation(s)
| | | | - Yalin Zhang
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, Yangling 712100, China.
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Zhou BH, Wang HW, Zhao ZS, Liu M, Yan WC, Zhao J, Zhang Z, Xue FQ. A novel serine/threonine protein phosphatase type 5 from second-generation merozoite of Eimeria tenella is associated with diclazuril-induced apoptosis. Parasitol Res 2013; 112:1771-80. [PMID: 23417098 DOI: 10.1007/s00436-013-3336-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 01/31/2013] [Indexed: 11/25/2022]
Abstract
Screening the anticoccidial drug targets is very important for developing novel drugs and revealing the molecular basis of drug resistance in coccidia. Due to high effectivity and safety, diclazuril was used widely in the poultry industry. To assess the roles of the serine/threonine protein phosphatase type 5 of second-generation merozoites in Eimeria tenella (EtPP5) in the anticoccidial activity of diclazuril against chicken coccidiosis, EtPP5 was cloned using reverse transcriptase polymerase chain reaction and rapid amplification of cDNA ends. Ultrastructural changes in second-generation merozoites and mRNA expression level of EtPP5 were monitored by transmission electron microscopy (TEM) and quantitative real-time PCR, respectively. The results showed that the full length of the cloned EtPP5 cDNA (2,495 bp) encompassed a 1,647-bp open reading frame encoding a polypeptide of 548 residues with an estimated molecular mass of 60.82 kDa and a theoretical isoelectric point of 5.89. Molecular analysis of EtPP5 reveals the presence of a C-terminal phosphatase domain and an extended N-terminal tetratricopeptide repeat motif, a typical feature of protein phosphatases. The cDNA sequence has been submitted to the GenBank database with accession number JX987508. EtPP5 shared 89% homology with the published sequence of a PP5 ortholog of Toxoplasma gondii at the amino acid level (GenBank XP_002364442.1). TEM observed that diclazuril induced ultrastructural changes in second-generation merozoites. Quantitative real-time PCR analysis showed that compared with the control group, the level of EtPP5 mRNA expression was significantly downregulated by 51.4% by diclazuril treatment. The high similarity of EtPP5 to previously described PP5 of other organisms, as well as its downregulated expression and connection with apoptosis in the second-generation merozoites induced by diclazuril, suggests that it could act an important role in understanding the signaling mechanism underlining the diclazuril-induced merozoites apoptosis.
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Affiliation(s)
- Bian-hua Zhou
- College of Animal Science and Technology, Henan University of Science and Technology, 70 Tianjin Road, Jianxi, Luoyang, Hehan, 471003, China
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Andreeva AV, Kutuzov MA. PPEF/PP7 protein Ser/Thr phosphatases. Cell Mol Life Sci 2009; 66:3103-10. [PMID: 19662497 PMCID: PMC11115641 DOI: 10.1007/s00018-009-0110-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2009] [Accepted: 07/15/2009] [Indexed: 12/14/2022]
Abstract
PPEF/PP7 represents one of the five subfamilies of the PPP protein Ser/Thr phosphatases. Studies published in recent years point to a role of plant PP7 at a crossroad of different pathways of light and stress signalling. In animals, PPEFs are highly expressed in sensory neurons, and Drosophila PPEF phosphatase, rdgC, is essential for dephosphorylation of rhodopsin. Expression profiling suggests that mammalian PPEF may play a role in stress-protective responses, cell survival, growth, proliferation, and oncogenesis. Despite structural similarities of the catalytic domains and the fact that some of these phosphatases are involved in light perception both in animals and in plants, the plant and non-plant representatives of this group have distinct domain architecture and appear not to be orthologues.
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Affiliation(s)
- Alexandra V. Andreeva
- Department of Pharmacology (M/C 868), College of Medicine, University of Illinois, 909 S. Wolcott Ave., Chicago, IL 60612 USA
| | - Mikhail A. Kutuzov
- Department of Pharmacology (M/C 868), College of Medicine, University of Illinois, 909 S. Wolcott Ave., Chicago, IL 60612 USA
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Petter M, Bonow I, Klinkert MQ. Diverse expression patterns of subgroups of the rif multigene family during Plasmodium falciparum gametocytogenesis. PLoS One 2008; 3:e3779. [PMID: 19020666 PMCID: PMC2582490 DOI: 10.1371/journal.pone.0003779] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Accepted: 11/02/2008] [Indexed: 12/14/2022] Open
Abstract
Background The maturation of Plasmodium falciparum gametocytes in the human host takes several days, during which the parasites need to efficiently evade the host immune system. Like asexual stage parasites, immature gametocytes can sequester at various sites in the human body, and only mature sexual stages are found in the circulation. Although the fundamental mechanisms of gametocyte immune evasion are still largely unknown, candidate molecules that may be involved include variant antigens encoded by multigene families in the P. falciparum genome, such as the PfEMP1, STEVOR and RIFIN proteins. While expression of the former two families in sexual stages has been investigated earlier, we report here RIFIN expression during gametocytogenesis. Methodology/Principal Findings Variants of two previously characterized RIFIN subfamilies (A- and B-type RIFINs) were found to be synthesized in gametocytes. Immunofluorescence experiments showed A-type RIFINs to be accumulated in a crescent-shaped pattern of discrete punctate structures at the infected erythrocyte membrane, while members of the B-type family were associated with the parasite. Transcription analysis demonstrated the existence of diverse transcriptional regulation patterns during sexual differentiation and indicated variant-specific regulation of B-type RIFINs, in contrast to group-specific regulation for A-type RIFINs. Phylogenetic analysis of 5′-upstream regions showed that the rif–gene family falls into five defined clusters, designated rups (rifupstream) A1, A2, AB, B and C. In trophozoites and early gametocytes, rif variants of the rupsA2-type were preferentially expressed. Conclusions/Significance In this work we demonstrate the expression dynamics of the rif-gene family during sexual differentiation and present indications for subgroup specific regulation patterns. Therefore, our data provide a first foundation and point to new directions for future investigations of the potential role of RIFINs in gametocyte immune evasion.
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Affiliation(s)
- Michaela Petter
- Bernhard Nocht-Institute for Tropical Medicine, Hamburg, Germany.
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Wilkes JM, Doerig C. The protein-phosphatome of the human malaria parasite Plasmodium falciparum. BMC Genomics 2008; 9:412. [PMID: 18793411 PMCID: PMC2559854 DOI: 10.1186/1471-2164-9-412] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 09/15/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria, caused by the parasitic protist Plasmodium falciparum, represents a major public health problem in the developing world. The P. falciparum genome has been sequenced, which provides new opportunities for the identification of novel drug targets. We report an exhaustive analysis of the P. falciparum genomic database (PlasmoDB) aimed at identifying and classifying all protein phosphatases (PP) in this organism. RESULTS Using a variety of bioinformatics tools, we identified 27 malarial putative PP sequences within the four major established PP families, plus 7 sequences that we predict to dephosphorylate "non-protein" substrates. We constructed phylogenetic trees to position these sequences relative to PPs from other organisms representing all major eukaryotic phyla except Cercozoans (for which no full genome sequence is available). Predominant observations were: (i) P. falciparum possessed the smallest phosphatome of any of the organisms investigated in this study; (ii) no malarial PP clustered with the tyrosine-specific subfamily of the PTP group (iii) a cluster of 7 closely related members of the PPM/PP2C family is present, and (iv) some P. falciparum protein phosphatases are present in clades lacking any human homologue. CONCLUSION The considerable phylogenetic distance between Apicomplexa and other Eukaryotes is reflected by profound divergences between the phosphatome of malaria parasites and those of representative organisms from all major eukaryotic phyla, which might be exploited in the context of efforts for the discovery of novel targets for antimalarial chemotherapy.
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Affiliation(s)
- Jonathan M Wilkes
- INSERM U609, Wellcome Centre for Molecular Parasitology, University of Glasgow, Glasgow, Scotland, UK.
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Kutuzov MA, Andreeva AV. Protein Ser/Thr phosphatases of parasitic protozoa. Mol Biochem Parasitol 2008; 161:81-90. [PMID: 18619495 DOI: 10.1016/j.molbiopara.2008.06.008] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 06/12/2008] [Accepted: 06/12/2008] [Indexed: 12/17/2022]
Abstract
Protein phosphorylation is an important mechanism implicated in physiology of any organism, including parasitic protozoa. Enzymes that control protein phosphorylation (kinases and phosphatases) are considered promising targets for drug development. This review attempts to provide the first account of the current understanding of the structure, regulation and biological functions of protein Ser/Thr phosphatases in unicellular parasites. We have examined the complements of phosphatases ("phosphatomes") of the PPP and PPM families in several species of Apicomplexa (including malaria parasite Plasmodium), as well as Giardia lamblia, Entamoeba histolytica, Trichomonas vaginalis and a microsporidium Encephalitozoon cuniculi. Apicomplexans have homologues (in most cases represented by single isoforms) of all human PPP subfamilies. Some apicomplexan PPP phosphatases have no orthologues in their vertebrate hosts, including a previously unrecognised group of pseudo-phosphatases with putative Ca(2+)-binding domains, which we designate as EFPP. We also describe the presence of previously undetected Zn finger motifs in PPEF phosphatases from kinetoplastids, and a likely case of convergent evolution of tetratricopeptide repeat domain-containing phosphatases in G. lamblia. Among the parasites examined, E. cuniculi has the smallest Ser/Thr phosphatome (5 PPP and no PPM), while T. vaginalis shows the largest expansion of the PPP family (169 predicted phosphatases). Most protozoan PPM phosphatases cluster separately from human sequences. The structural peculiarities or absence of human orthologues of a number of protozoan protein Ser/Thr phosphatases makes them potentially suitable targets for chemotherapy and thus warrants their functional assessment.
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Affiliation(s)
- Mikhail A Kutuzov
- Department of Pharmacology, University of Illinois at Chicago, 909 S. Wolcott Avenue, Chicago, IL 60612, USA.
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Haider N, Eschbach ML, Dias SDS, Gilberger TW, Walter RD, Lüersen K. The spermidine synthase of the malaria parasite Plasmodium falciparum: Molecular and biochemical characterisation of the polyamine synthesis enzyme. Mol Biochem Parasitol 2005; 142:224-36. [PMID: 15913804 DOI: 10.1016/j.molbiopara.2005.04.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2005] [Revised: 03/24/2005] [Accepted: 04/18/2005] [Indexed: 10/25/2022]
Abstract
The gene encoding spermidine synthase was cloned from the human malaria parasite Plasmodium falciparum. Northern and Western blot analyses revealed a stage specific expression during the erythrocytic schizogony with the maximal amount of transcript and protein in mature trophozoites. Immunofluorescence assays (IFAs) suggest a cytoplasmatic localisation of the spermidine synthase in P. falciparum. The spermidine synthase polypeptide of 321 amino acids has a molecular mass of 36.6kDa and contains an N-terminal extension of unknown function that, similarly, is also found in certain plants but not in animal or bacterial orthologues. Omitting the first 29 amino acids, a truncated form of P. falciparum spermidine synthase has been recombinantly expressed in Escherichia coli. The enzyme catalyses the transfer of an aminopropyl group from decarboxylated S-adenosylmethionine (dcAdoMet) onto putrescine with Km values of 35 and 52microM, respectively. In contrast to mammalian spermidine synthases, spermidine can replace to some extent putrescine as the aminopropyl acceptor. Hence, P. falciparum spermidine synthase has the capacity to catalyse the formation of spermine that is found in small amounts in the erythrocytic stages of the parasite. Among the spermidine synthase inhibitors tested against P. falciparum spermidine synthase, trans-4-methylcyclohexylamine (4MCHA) was found to be most potent with a Ki value of 0.18microM. In contrast to the situation in mammals, where inhibition of spermidine synthase has no or only little effect on cell proliferation, 4MCHA was an efficient inhibitor of P. falciparum cell growth in vitro with an IC50 of 35microM, indicating that P. falciparum spermidine synthase represents a putative drug target.
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Affiliation(s)
- Nashya Haider
- Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Str. 74, D-20359 Hamburg, Germany
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19
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Zeke T, Morrice N, Vázquez-Martin C, Cohen P. Human protein phosphatase 5 dissociates from heat-shock proteins and is proteolytically activated in response to arachidonic acid and the microtubule-depolymerizing drug nocodazole. Biochem J 2005; 385:45-56. [PMID: 15383005 PMCID: PMC1134672 DOI: 10.1042/bj20040690] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ppp5 (protein phosphatase 5) is a serine/threonine protein phosphatase that has been conserved throughout eukaryotic evolution. In mammalian cells, FLAG-tagged Ppp5 and endogenous Ppp5 are found to interact with endogenous Hsp (heat-shock protein) 70, as well as Hsp90. Incubation of cells with arachidonic acid or the microtubule-depolymerizing agent, nocodazole, causes loss of interaction of Hsp70 and Hsp90 with FLAG-tagged Ppp5 and increase of Ppp5 activity. In response to the same treatments, endogenous Ppp5 undergoes proteolytic cleavage of the N- and C-termini, with the subsequent appearance of high-molecular-mass species. The results indicate that Ppp5 is activated by proteolysis on dissociation from Hsps, and is destroyed via the proteasome after ubiquitination. Cleavage at the C-terminus removes a nuclear localization sequence, allowing these active cleaved forms of Ppp5 to translocate to the cytoplasm. The response of Ppp5 to arachidonic acid and nocodazole suggests that Ppp5 may be required for stress-related processes that can sometimes cause cell-cycle arrest, and leads to the first description for in vivo regulation of Ppp5 activity.
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Affiliation(s)
- Tamás Zeke
- Medical Research Council Protein Phosphorylation Unit, Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Nick Morrice
- Medical Research Council Protein Phosphorylation Unit, Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Cristina Vázquez-Martin
- Medical Research Council Protein Phosphorylation Unit, Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Patricia T. W. Cohen
- Medical Research Council Protein Phosphorylation Unit, Division of Cell Signalling, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
- To whom correspondence should be addressed (email )
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Zhou Z, Schnake P, Xiao L, Lal AA. Enhanced expression of a recombinant malaria candidate vaccine in Escherichia coli by codon optimization. Protein Expr Purif 2004; 34:87-94. [PMID: 14766303 DOI: 10.1016/j.pep.2003.11.006] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2003] [Revised: 11/09/2003] [Indexed: 11/23/2022]
Abstract
This study was conducted to compare the expression of three constructs of a multistage candidate vaccine (FALVAC-1) against Plasmodium falciparum in an Escherichia coli system: a synthetic gene with P. falciparum codons, a synthetic gene with optimized E. coli codons, and a synthetic gene with P. falciparum codons co-transformed with a RIG plasmid, which encodes three tRNAs (AG(A/G), ATA, GGA) that recognize rare E. coli codons. The expression of the protein increased at least threefold with codon optimization. The presence of the RIG plasmid in the co-transforming cells did not significantly increase the expression level of the gene with P. falciparum codons. The growth of cells transformed by the construct with P. falciparum codons was significantly slower than that of cells transformed by the construct with optimized E. coli codons after induction of protein expression with IPTG. The cells containing the non-codon optimized gene co-expressed with RIG plasmid had the slowest growth at all time points in culture. Thus, codon optimization significantly increases the yield of P. falciparum candidate vaccines in the E. coli expression system.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Protozoan/genetics
- Base Sequence
- Blotting, Western
- Cell Division/genetics
- Chromatography, Agarose
- Cloning, Molecular
- Codon/genetics
- DNA, Protozoan/genetics
- DNA, Protozoan/immunology
- Electrophoresis, Polyacrylamide Gel
- Epitopes/genetics
- Epitopes/immunology
- Escherichia coli/genetics
- Escherichia coli/growth & development
- Gene Expression/drug effects
- Gene Expression/genetics
- Gene Expression Regulation, Bacterial
- Genes, Synthetic/genetics
- Genes, Synthetic/immunology
- Genetic Vectors/genetics
- Isopropyl Thiogalactoside/pharmacology
- Malaria Vaccines/analysis
- Malaria Vaccines/biosynthesis
- Malaria Vaccines/genetics
- Molecular Sequence Data
- Plasmodium falciparum/genetics
- Plasmodium falciparum/immunology
- Protein Engineering/methods
- RNA, Transfer/genetics
- Sequence Alignment
- Sequence Homology, Nucleic Acid
- Vaccines, Synthetic/analysis
- Vaccines, Synthetic/biosynthesis
- Vaccines, Synthetic/genetics
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Affiliation(s)
- Zhiyong Zhou
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, 4770 Buford Highway, Chamblee, GA 30341, USA.
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Kumar R, Musiyenko A, Oldenburg A, Adams B, Barik S. Post-translational generation of constitutively active cores from larger phosphatases in the malaria parasite, Plasmodium falciparum: implications for proteomics. BMC Mol Biol 2004; 5:6. [PMID: 15230980 PMCID: PMC459218 DOI: 10.1186/1471-2199-5-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Accepted: 07/01/2004] [Indexed: 11/16/2022] Open
Abstract
Background Although the complete genome sequences of a large number of organisms have been determined, the exact proteomes need to be characterized. More specifically, the extent to which post-translational processes such as proteolysis affect the synthesized proteins has remained unappreciated. We examined this issue in selected protein phosphatases of the protease-rich malaria parasite, Plasmodium falciparum. Results P. falciparum encodes a number of Ser/Thr protein phosphatases (PP) whose catalytic subunits are composed of a catalytic core and accessory domains essential for regulation of the catalytic activity. Two examples of such regulatory domains are found in the Ca+2-regulated phosphatases, PP7 and PP2B (calcineurin). The EF-hand domains of PP7 and the calmodulin-binding domain of PP2B are essential for stimulation of the phosphatase activity by Ca+2. We present biochemical evidence that P. falciparum generates these full-length phosphatases as well as their catalytic cores, most likely as intermediates of a proteolytic degradation pathway. While the full-length phosphatases are activated by Ca+2, the processed cores are constitutively active and either less responsive or unresponsive to Ca+2. The processing is extremely rapid, specific, and occurs in vivo. Conclusions Post-translational cleavage efficiently degrades complex full-length phosphatases in P. falciparum. In the course of such degradation, enzymatically active catalytic cores are produced as relatively stable intermediates. The universality of such proteolysis in other phosphatases or other multi-domain proteins and its potential impact on the overall proteome of a cell merits further investigation.
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Affiliation(s)
- Rajinder Kumar
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Alla Musiyenko
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Anja Oldenburg
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Brian Adams
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Sailen Barik
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
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de la Fuente van Bentem S, Vossen JH, Vermeer JEM, de Vroomen MJ, Gadella TWJ, Haring MA, Cornelissen BJC. The subcellular localization of plant protein phosphatase 5 isoforms is determined by alternative splicing. PLANT PHYSIOLOGY 2003; 133:702-12. [PMID: 12972652 PMCID: PMC219045 DOI: 10.1104/pp.103.026617] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2003] [Revised: 06/24/2003] [Accepted: 07/08/2003] [Indexed: 05/18/2023]
Abstract
Protein serine/threonine phosphatase 5 (PP5) plays an important role in signal transduction in animal cells, but in plants, knowledge about PP5 is scarce. Here, we describe the isolation of a full-length cDNA encoding tomato (Lycopersicon esculentum) PP5 (LePP5) and its expression in Escherichia coli. Biochemical characterization showed that recombinant LePP5 has a low intrinsic protein phosphatase activity. This activity was increased 6- to 10-fold by either removal of the N-terminal tetratricopeptide repeat domain or by addition of fatty acids, indicating that biochemical features specific for PP5 homologs from other species are conserved in tomato. The single-copy LePP5 gene was cloned and shown to encode two mRNA species that arise by alternative pre-mRNA splicing. Similarly, Arabidopsis was found to express two PP5 transcripts, suggesting that alternative splicing of PP5 pre-mRNA is not specific for tomato. Alternative splicing results in a larger transcript containing an additional exon encoding two putative transmembrane domains and, hence, in a larger PP5 isoform. Subcellular fractionation studies on tomato protein lysates indicated that the majority of the 55-kD LePP5 isoform is soluble, whereas the 62-kD isoform is an integral membrane protein. Production of yellow fluorescent protein-PP5 chimeras in plant cells indicated that the 55-kD isoform is localized in both the nucleus and the cytoplasm, whereas the 62-kD isoform is targeted to the endoplasmic reticulum, including the nuclear envelope. Our findings show that alternative splicing generates two LePP5 isoforms with a different subcellular localization.
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Affiliation(s)
- Sergio de la Fuente van Bentem
- Plant Pathology, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, P.O. Box 94062, 1090 GB Amsterdam, The Netherlands
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Kumar R, Musiyenko A, Barik S. The heat shock protein 90 of Plasmodium falciparum and antimalarial activity of its inhibitor, geldanamycin. Malar J 2003; 2:30. [PMID: 14514358 PMCID: PMC201030 DOI: 10.1186/1475-2875-2-30] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2003] [Accepted: 09/15/2003] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The naturally occurring benzoquinone ansamycin compound, geldanamycin (GA), is a specific inhibitor of heat shock protein 90 (Hsp90) and is a potential anticancer agent. Since Plasmodium falciparum has been reported to have an Hsp90 ortholog, we tested the possibility that GA might inhibit it and thereby display antiparasitic activity. RESULTS We provide direct recombinant DNA evidence for the Hsp90 protein of Plasmodium falciparum, the causative agent of fatal malaria. While the mRNA of Hsp90 was mainly expressed in ring and trophozoite stages, the protein was found in all stages, although schizonts contained relatively lower amounts. In vitro the parasitic Hsp90 exhibited an ATP-binding activity that could be specifically inhibited by GA. Plasmodium growth in human erythrocyte culture was strongly inhibited by GA with an IC50 of 20 nM, compared to the IC50 of 15 nM for chloroquine (CQ) under identical conditions. When used in combination, the two drugs acted synergistically. GA was equally effective against CQ-sensitive and CQ-resistant strains (3D7 and W2, respectively) and on all erythrocytic stages of the parasite. CONCLUSIONS Together, these results suggest that an active and essential Hsp90 chaperone cycle exists in Plasmodium and that the ansamycin antibiotics will be an important tool to dissect its role in the parasite. Additionally, the favorable pharmacology of GA, reported in human trials, makes it a promising antimalarial drug.
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Affiliation(s)
- Rajinder Kumar
- Department of Biochemistry and Molecular Biology (MSB 2370), University of South Alabama, College of Medicine, 307 University Blvd, Mobile, AL 36688-0002, USA.
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24
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Wiser MF. A Plasmodium homologue of cochaperone p23 and its differential expression during the replicative cycle of the malaria parasite. Parasitol Res 2003; 90:166-70. [PMID: 12756555 DOI: 10.1007/s00436-003-0835-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2002] [Accepted: 01/17/2003] [Indexed: 10/25/2022]
Abstract
The complete gene sequence of a major phosphoprotein from the malaria parasite reveals that it is a homologue to cochaperone p23. This p23 homologue is highly conserved between Plasmodium falciparum and other malaria parasites and exhibits 44% sequence identity with the Schizosaccharomyces pombe p23 homologue. The Plasmodium p23 is a relatively abundant cytoplasmic protein with a molecular mass of 34-36 kDa depending on species. Expression of this 34 kDa protein and its mRNA commences in the early ring stage and continues throughout the trophozoite stage. At the beginning of schizogony there is a decrease in the transcription and translation rates and a decline in the amount of the 34 kDa protein. The exact role of the 34 kDa phosphoprotein in parasite replication and differentiation is not known, but the Plasmodium p23 homologue may play a role in parasite proliferation and differentiation through its interactions with protein kinases and other chaperones.
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Affiliation(s)
- Mark F Wiser
- Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, 1440 Canal Street, SL17, New Orleans, LA 70112, USA.
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25
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Jeong JY, Johns J, Sinclair C, Park JM, Rossie S. Characterization of Saccharomyces cerevisiae protein Ser/Thr phosphatase T1 and comparison to its mammalian homolog PP5. BMC Cell Biol 2003; 4:3. [PMID: 12694636 PMCID: PMC153538 DOI: 10.1186/1471-2121-4-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2002] [Accepted: 03/28/2003] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Protein Ser/Thr phosphatase 5 (PP5) and its Saccharomyces cerevisiae homolog protein phosphatase T1 (Ppt1p) each contain an N-terminal domain consisting of several tetratricopeptide repeats (TPRs) and a C-terminal catalytic domain that is related to the catalytic subunits of protein phosphatases 1 and 2A, and calcineurin. Analysis of yeast Ppt1p could provide important clues to the function of PP5 and its homologs, however it has not yet been characterized at the biochemical or cellular level. RESULTS The specific activity of recombinant Ppt1p toward the artificial substrates 32P-myelin basic protein (MBP) and 32P-casein was similar to that of PP5. Dephosphorylation of 32P-MBP, but not 32P-casein, was stimulated by unsaturated fatty acids and by arachidoyl coenzyme A. Limited proteolysis of Ppt1p removed the TPR domain and abrogated lipid stimulation. The remaining catalytic fragment exhibited a two-fold increase in activity toward 32P-MBP, but not 32P-casein. Removal of the C terminus increased Ppt1p activity toward both substrates two fold, but did not prevent further stimulation of activity toward 32P-MBP by lipid treatment. Ppt1p was localized throughout the cell including the nucleus. Levels of PPT1 mRNA and protein peaked in early log phase growth. CONCLUSIONS Many characteristics of Ppt1p are similar to those of PP5, including stimulation of phosphatase activity with some substrates by lipids, and peak expression during periods of rapid cell growth. Unlike PP5, however, proteolytic removal of the TPR domain or C-terminal truncation only modestly increased its activity. In addition, C-terminal truncation did not prevent further activation by lipid. This suggests that these regions play only a minor role in controlling its activity compared to PP5. Ppt1p is present in both the nucleus and cytoplasm, indicating that it may function in multiple compartments. The observation that Ppt1p is most highly expressed during early log phase growth suggests that this enzyme is involved in cell growth or its expression is controlled by metabolic or nutritional signals.
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Affiliation(s)
- Jee-Yeong Jeong
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Jeremiah Johns
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | | | - Jung-Min Park
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Sandra Rossie
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
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Abdel-Latif MS, Khattab A, Lindenthal C, Kremsner PG, Klinkert MQ. Recognition of variant Rifin antigens by human antibodies induced during natural Plasmodium falciparum infections. Infect Immun 2002; 70:7013-21. [PMID: 12438381 PMCID: PMC132968 DOI: 10.1128/iai.70.12.7013-7021.2002] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antibodies from individuals living in areas where malaria is endemic are known to react with parasite-derived erythrocyte surface proteins. The major immunogenic and clonally variant surface antigen described to date is Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP-1), which is encoded by members of the multicopy var gene family. We report here that rifin proteins (RIF proteins), belonging to the largest known family of variable infected erythrocyte surface-expressed proteins, are also naturally immunogenic. Recombinant RIF proteins were used to analyze the antibody responses of individuals living in an area of intense malaria transmission. Elevated anti-rifin antibody levels were detected in the majority of the adult population tested, whereas the prevalence of such antibodies was much lower in malaria-exposed children. Despite the high degree of diversity between rif sequences and the high gene copy number, it appears that P. falciparum infections can induce antibodies that cross-react with several variant rifin molecules in many parasite isolates in a given community, and the immune response is most likely to be stable over time in a hyperendemic area. The protein was localized by fluorescence microscopy on the membrane of ring and young trophozoite-infected erythrocytes with antibodies from human immune sera with specificities for recombinant RIF protein.
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Affiliation(s)
- Mohamed S Abdel-Latif
- Department of Parasitology, Institute for Tropical Medicine, University of Tübingen, Germany
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