1
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Jamabo M, Mahlalela M, Edkins AL, Boshoff A. Tackling Sleeping Sickness: Current and Promising Therapeutics and Treatment Strategies. Int J Mol Sci 2023; 24:12529. [PMID: 37569903 PMCID: PMC10420020 DOI: 10.3390/ijms241512529] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/27/2023] [Accepted: 08/03/2023] [Indexed: 08/13/2023] Open
Abstract
Human African trypanosomiasis is a neglected tropical disease caused by the extracellular protozoan parasite Trypanosoma brucei, and targeted for eradication by 2030. The COVID-19 pandemic contributed to the lengthening of the proposed time frame for eliminating human African trypanosomiasis as control programs were interrupted. Armed with extensive antigenic variation and the depletion of the B cell population during an infectious cycle, attempts to develop a vaccine have remained unachievable. With the absence of a vaccine, control of the disease has relied heavily on intensive screening measures and the use of drugs. The chemotherapeutics previously available for disease management were plagued by issues such as toxicity, resistance, and difficulty in administration. The approval of the latest and first oral drug, fexinidazole, is a major chemotherapeutic achievement for the treatment of human African trypanosomiasis in the past few decades. Timely and accurate diagnosis is essential for effective treatment, while poor compliance and resistance remain outstanding challenges. Drug discovery is on-going, and herein we review the recent advances in anti-trypanosomal drug discovery, including novel potential drug targets. The numerous challenges associated with disease eradication will also be addressed.
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Affiliation(s)
- Miebaka Jamabo
- Biotechnology Innovation Centre, Rhodes University, Makhanda 6139, South Africa; (M.J.); (M.M.)
| | - Maduma Mahlalela
- Biotechnology Innovation Centre, Rhodes University, Makhanda 6139, South Africa; (M.J.); (M.M.)
| | - Adrienne L. Edkins
- Department of Biochemistry and Microbiology, Biomedical Biotechnology Research Centre (BioBRU), Rhodes University, Makhanda 6139, South Africa;
| | - Aileen Boshoff
- Biotechnology Innovation Centre, Rhodes University, Makhanda 6139, South Africa; (M.J.); (M.M.)
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2
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Saini LK, Bheri M, Pandey GK. Protein phosphatases and their targets: Comprehending the interactions in plant signaling pathways. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 134:307-370. [PMID: 36858740 DOI: 10.1016/bs.apcsb.2022.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Protein phosphorylation is a vital reversible post-translational modification. This process is established by two classes of enzymes: protein kinases and protein phosphatases. Protein kinases phosphorylate proteins while protein phosphatases dephosphorylate phosphorylated proteins, thus, functioning as 'critical regulators' in signaling pathways. The eukaryotic protein phosphatases are classified as phosphoprotein phosphatases (PPP), metallo-dependent protein phosphatases (PPM), protein tyrosine (Tyr) phosphatases (PTP), and aspartate (Asp)-dependent phosphatases. The PPP and PPM families are serine (Ser)/threonine (Thr) specific phosphatases (STPs) that dephosphorylate Ser and Thr residues. The PTP family dephosphorylates Tyr residues while dual-specificity phosphatases (DsPTPs/DSPs) dephosphorylate Ser, Thr, and Tyr residues. The composition of these enzymes as well as their substrate specificity are important determinants of their functional significance in a number of cellular processes and stress responses. Their role in animal systems is well-understood and characterized. The functional characterization of protein phosphatases has been extensively covered in plants, although the comprehension of their mechanistic basis is an ongoing pursuit. The nature of their interactions with other key players in the signaling process is vital to our understanding. The substrates or targets determine their potential as well as magnitude of the impact they have on signaling pathways. In this article, we exclusively overview the various substrates of protein phosphatases in plant signaling pathways, which are a critical determinant of the outcome of various developmental and stress stimuli.
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Affiliation(s)
- Lokesh K Saini
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India
| | - Malathi Bheri
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India
| | - Girdhar K Pandey
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India.
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3
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Salari S, Bamorovat M, Sharifi I, Almani PGN. Global distribution of treatment resistance gene markers for leishmaniasis. J Clin Lab Anal 2022; 36:e24599. [PMID: 35808933 PMCID: PMC9396204 DOI: 10.1002/jcla.24599] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 06/19/2022] [Accepted: 06/28/2022] [Indexed: 01/02/2023] Open
Abstract
Background Pentavalent antimonials (Sb(V)) such as meglumine antimoniate (Glucantime®) and sodium stibogluconate (Pentostam®) are used as first‐line treatments for leishmaniasis, either alone or in combination with second‐line drugs such as amphotericin B (Amp B), miltefosine (MIL), methotrexate (MTX), or cryotherapy. Therapeutic aspects of these drugs are now challenged because of clinical resistance worldwide. Methods We reviewedthe recent original studies were assessed by searching in electronic databases such as Scopus, Pubmed, Embase, and Web of Science. Results Studies on molecular biomarkers involved in drug resistance are essential for monitoring the disease. We reviewed genes and mechanisms of resistance to leishmaniasis, and the geographical distribution of these biomarkers in each country has also been thoroughly investigated. Conclusion Due to the emergence of resistant genes mainly in anthroponotic Leishmania species such as L. donovani and L. tropica, as the causative agents of ACL and AVL, respectively, selection of an appropriate treatment modality is essential. Physicians should be aware of the presence of such resistance for the selection of proper treatment modalities in endemic countries.
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Affiliation(s)
- Samira Salari
- Medical Mycology and Bacteriology Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Mehdi Bamorovat
- Leishmaniasis Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Iraj Sharifi
- Leishmaniasis Research Center, Kerman University of Medical Sciences, Kerman, Iran
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4
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Bustamante C, Muskus C, Ochoa R. Rational computational approaches to predict novel drug candidates against leishmaniasis. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2022. [DOI: 10.1016/bs.armc.2022.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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5
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Parasite protein phosphatases: biological function, virulence, and host immune evasion. Parasitol Res 2021; 120:2703-2715. [PMID: 34309709 DOI: 10.1007/s00436-021-07259-9] [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: 02/09/2021] [Accepted: 07/18/2021] [Indexed: 10/20/2022]
Abstract
Protein phosphatases are enzymes that dephosphorylate tyrosine and serine/threonine amino acid residues. Although their role in cellular processes has been best characterized in higher eukaryotes, they have also been identified and studied in different pathogenic microorganisms (e.g., parasites) in the last two decades. Whereas some parasite protein phosphatases carry out functions similar to those of their homologs in yeast and mammalian cells, others have unique structural and/or functional characteristics. Thus, the latter unique phosphatases may be instrumental as targets for drug therapy or as markers for diagnosis. It is important to better understand the involvement of protein phosphatases in parasites in relation to their cell cycle, metabolism, virulence, and evasion of the host immune response. The up-to-date information about parasite phosphatases of medical and veterinarian relevance is herein reviewed.
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6
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Freitas-Mesquita AL, Dos-Santos ALA, Meyer-Fernandes JR. Involvement of Leishmania Phosphatases in Parasite Biology and Pathogeny. Front Cell Infect Microbiol 2021; 11:633146. [PMID: 33968798 PMCID: PMC8100340 DOI: 10.3389/fcimb.2021.633146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 04/06/2021] [Indexed: 01/01/2023] Open
Abstract
In the Leishmania lifecycle, the motile promastigote form is transmitted from the sand fly vector to a mammalian host during a blood meal. Inside vertebrate host macrophages, the parasites can differentiate into the amastigote form and multiply, causing leishmaniasis, one of the most significant neglected tropical diseases. Leishmania parasites face different conditions throughout their development inside sand flies. Once in the mammalian host, the parasites have to overcome the microbicide repertoire of the cells of the immune system to successfully establish the infection. In this context, the expression of protein phosphatases is of particular interest. Several members of the serine/threonine-specific protein phosphatase (STP), protein tyrosine phosphatase (PTP), and histidine acid phosphatase (HAcP) families have been described in different Leishmania species. Although their physiological roles have not been fully elucidated, many studies suggest they have an involvement with parasite biology and pathogeny. Phosphatases play a role in adaptation to nutrient starvation during parasite passage through the sand fly midgut. They are also important to parasite virulence, mainly due to the modulation of host cytokine production and impairment of the microbiocidal potential of macrophages. Furthermore, recent whole-genome expression analyses have shown that different phosphatases are upregulated in metacyclic promastigotes, the infective form of the mammalian host. Leishmania phosphatases are also upregulated in drug-resistant strains, probably due to the increase in drug efflux related to the activation of ABC transporters. Throughout this review, we will describe the physiological roles that have been attributed to Leishmania endogenous phosphatases, including their involvement in the adaptation, survival, and proliferation of the parasites inside their hosts.
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Affiliation(s)
- Anita Leocadio Freitas-Mesquita
- Instituto de Bioquímica Médica Leopoldo De Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - André Luiz Araújo Dos-Santos
- Instituto de Bioquímica Médica Leopoldo De Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - José Roberto Meyer-Fernandes
- Instituto de Bioquímica Médica Leopoldo De Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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7
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Bell AS, Yu Z, Hutton JA, Wright MH, Brannigan JA, Paape D, Roberts SM, Sutherell CL, Ritzefeld M, Wilkinson AJ, Smith DF, Leatherbarrow RJ, Tate EW. Novel Thienopyrimidine Inhibitors of Leishmania N-Myristoyltransferase with On-Target Activity in Intracellular Amastigotes. J Med Chem 2020; 63:7740-7765. [PMID: 32575985 PMCID: PMC7383931 DOI: 10.1021/acs.jmedchem.0c00570] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
![]()
The
leishmaniases, caused by Leishmania species
of protozoan parasites, are neglected tropical diseases with millions
of cases worldwide. Current therapeutic approaches are limited by
toxicity, resistance, and cost. N-Myristoyltransferase
(NMT), an enzyme ubiquitous and essential in all eukaryotes, has been
validated via genetic and pharmacological methods as a promising anti-leishmanial
target. Here we describe a comprehensive structure–activity
relationship (SAR) study of a thienopyrimidine series previously identified
in a high-throughput screen against Leishmania NMT,
across 68 compounds in enzyme- and cell-based assay formats. Using
a chemical tagging target engagement biomarker assay, we identify
the first inhibitor in this series with on-target NMT activity in
leishmania parasites. Furthermore, crystal structure analyses of 12
derivatives in complex with Leishmania major NMT revealed key factors important for future structure-guided optimization
delivering IMP-105 (43), a compound with modest activity
against Leishmania donovani intracellular
amastigotes and excellent selectivity (>660-fold) for Leishmania NMT over human NMTs.
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Affiliation(s)
- Andrew S Bell
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, London, U.K. W12 0BZ
| | - Zhiyong Yu
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, London, U.K. W12 0BZ
| | - Jennie A Hutton
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, London, U.K. W12 0BZ
| | - Megan H Wright
- School of Chemistry, University of Leeds, Leeds, U.K. LS2 9JT
| | - James A Brannigan
- Structural Biology Laboratory, York Biomedical Research Institute, Department of Chemistry, University of York, York, U.K. YO10 5DD
| | - Daniel Paape
- Centre for Immunology and Infection, York Biomedical Research Institute, Department of Biology, University of York, York, U.K. YO10 5NG
| | - Shirley M Roberts
- Structural Biology Laboratory, York Biomedical Research Institute, Department of Chemistry, University of York, York, U.K. YO10 5DD
| | - Charlotte L Sutherell
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, London, U.K. W12 0BZ
| | - Markus Ritzefeld
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, London, U.K. W12 0BZ
| | - Anthony J Wilkinson
- Structural Biology Laboratory, York Biomedical Research Institute, Department of Chemistry, University of York, York, U.K. YO10 5DD
| | - Deborah F Smith
- Centre for Immunology and Infection, York Biomedical Research Institute, Department of Biology, University of York, York, U.K. YO10 5NG
| | - Robin J Leatherbarrow
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, London, U.K. W12 0BZ
| | - Edward W Tate
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, London, U.K. W12 0BZ
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8
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Junqueira LO, Costa MOLD, Rando DGG. N-Myristoyltransferases as antileishmanial targets: a piggyback approach with benzoheterocyclic analogues. BRAZ J PHARM SCI 2019. [DOI: 10.1590/s2175-97902019000218087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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9
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Strauch L, Pfannstiel J, Huber A, Voolstra O. Solubility and subcellular localization of the three Drosophila RDGC phosphatase variants are determined by acylation. FEBS Lett 2018; 592:2403-2413. [PMID: 29920663 DOI: 10.1002/1873-3468.13163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 06/06/2018] [Accepted: 06/11/2018] [Indexed: 01/26/2023]
Abstract
Protein phosphorylation is an abundant molecular switch that regulates a multitude of cellular processes. In contrast to other subfamilies of phosphoprotein phosphatases, the PPEF subfamily is only poorly investigated. Drosophila retinal degeneration C (RDGC) constitutes the founding member of the PPEF subfamily. RDGC dephosphorylates the visual pigment rhodopsin and the ion channel TRP.However, rdgC null mutant flies exhibit rhodopsin and TRP hyperphosphorylation, altered photoreceptor physiology, and retinal degeneration. Here, we report the identification of a third RDGC protein variant and show that the three RDGC isoforms harbor different N-termini that determine solubility and subcellular targeting due to fatty acylation. Taken together, solubility and subcellular targeting of RDGC splice variants are determined by their N-termini.
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Affiliation(s)
- Lisa Strauch
- Department of Biosensorics, Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Jens Pfannstiel
- Core Facility, Mass Spectrometry Unit, University of Hohenheim, Stuttgart, Germany
| | - Armin Huber
- Department of Biosensorics, Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Olaf Voolstra
- Department of Biosensorics, Institute of Physiology, University of Hohenheim, Stuttgart, Germany
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10
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Oliveira MP, Martins VT, Santos TTO, Lage DP, Ramos FF, Salles BCS, Costa LE, Dias DS, Ribeiro PAF, Schneider MS, Machado-de-Ávila RA, Teixeira AL, Coelho EAF, Chávez-Fumagalli MA. Small Myristoylated Protein-3, Identified as a Potential Virulence Factor in Leishmania amazonensis, Proves to be a Protective Antigen against Visceral Leishmaniasis. Int J Mol Sci 2018; 19:E129. [PMID: 29301342 PMCID: PMC5796078 DOI: 10.3390/ijms19010129] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/14/2017] [Accepted: 12/25/2017] [Indexed: 11/23/2022] Open
Abstract
In a proteomics approach conducted with Leishmania amazonensis, parasite proteins showed either an increase or a decrease in their expression content during extensive in vitro cultivation, and were related to the survival and the infectivity of the parasites, respectively. In the current study, a computational screening was performed to predict virulence factors among these molecules. Three proteins were selected, one of which presented no homology to human proteins. This candidate, namely small myristoylated protein-3 (SMP-3), was cloned, and its recombinant version (rSMP-3) was used to stimulate peripheral blood mononuclear cells (PBMCs) from healthy subjects living in an endemic area of leishmaniasis and from visceral leishmaniasis patients. Results showed high interferon-γ (IFN-γ) production and low levels of interleukin 10 (IL-10) in the cell supernatants. An in vivo experiment was then conducted on BALB/c mice, which were immunized with rSMP-3/saponin and later challenged with Leishmania infantum promastigotes. The rSMP-3/saponin combination induced high production of protein-specific IFN-γ, IL-12, and granulocyte-macrophage colony-stimulating factor (GM-CSF) by the spleen cells of the immunized mice. This pattern was associated with protection, which was characterized by a significant reduction in the parasite load in distinct organs of the animals. Altogether, these results have revealed that this new virulence factor is immunogenic in both mice and humans, and have proven its protective efficacy against visceral leishmaniasis in a murine model.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/metabolism
- Computational Biology
- Cytokines/metabolism
- Epitopes, T-Lymphocyte/metabolism
- Humans
- Immunity, Cellular
- Immunity, Humoral
- Leishmania/pathogenicity
- Leishmania infantum
- Leishmaniasis, Visceral/immunology
- Leishmaniasis, Visceral/parasitology
- Leishmaniasis, Visceral/prevention & control
- Leukocytes, Mononuclear/metabolism
- Linear Models
- Mice, Inbred BALB C
- Molecular Sequence Annotation
- Protozoan Proteins/chemistry
- Protozoan Proteins/metabolism
- Reproducibility of Results
- Structural Homology, Protein
- Virulence Factors/metabolism
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Affiliation(s)
- Marcelo P Oliveira
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Vívian T Martins
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Thaís T O Santos
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Daniela P Lage
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Fernanda F Ramos
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Beatriz C S Salles
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Lourena E Costa
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Daniel S Dias
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Patrícia A F Ribeiro
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Mônica S Schneider
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
| | - Ricardo A Machado-de-Ávila
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma 88806-000, Santa Catarina, Brazil.
| | - Antônio L Teixeira
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
- Laboratório Interdisciplinar de Investigação Médica, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
- Neuropsychiatry Program, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, 1941 East Road, Houston, TX 77041, USA.
| | - Eduardo A F Coelho
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
- Departamento de Patologia Clínica, do Colégio Técnico (COLTEC), Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Miguel A Chávez-Fumagalli
- Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte 30130-100, Minas Gerais, Brazil.
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11
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Soulat D, Bogdan C. Function of Macrophage and Parasite Phosphatases in Leishmaniasis. Front Immunol 2017; 8:1838. [PMID: 29312331 PMCID: PMC5743797 DOI: 10.3389/fimmu.2017.01838] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 12/05/2017] [Indexed: 01/23/2023] Open
Abstract
The kinetoplastid protozoan parasites belonging to the genus Leishmania are the causative agents of different clinical forms of leishmaniasis, a vector-borne infectious disease with worldwide prevalence. The protective host immune response against Leishmania parasites relies on myeloid cells such as dendritic cells and macrophages in which upon stimulation by cytokines (e.g., interferon-γ) a complex network of signaling pathways is switched on leading to strong antimicrobial activities directed against the intracellular parasite stage. The regulation of these pathways classically depends on post-translational modifications of proteins, with phosphorylation events playing a cardinal role. Leishmania parasites deactivate their phagocytic host cells by inducing specific mammalian phosphatases that are capable to impede signaling. On the other hand, there is now also evidence that Leishmania spp. themselves express phosphatases that might target host cell molecules and thereby facilitate the intracellular survival of the parasite. This review will present an overview on the modulation of host phosphatases by Leishmania parasites as well as on the known families of Leishmania phosphatases and their possible function as virulence factors. A more detailed understanding of the role of phosphatases in Leishmania–host cell interactions might open new avenues for the treatment of non-healing, progressive forms of leishmaniasis.
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Affiliation(s)
- Didier Soulat
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany.,Medical Immunology Campus Erlangen, Interdisciplinary Center of the FAU, Erlangen, Germany
| | - Christian Bogdan
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany.,Medical Immunology Campus Erlangen, Interdisciplinary Center of the FAU, Erlangen, Germany
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12
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Brown RWB, Sharma AI, Engman DM. Dynamic protein S-palmitoylation mediates parasite life cycle progression and diverse mechanisms of virulence. Crit Rev Biochem Mol Biol 2017; 52:145-162. [PMID: 28228066 PMCID: PMC5560270 DOI: 10.1080/10409238.2017.1287161] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Eukaryotic parasites possess complex life cycles and utilize an assortment of molecular mechanisms to overcome physical barriers, suppress and/or bypass the host immune response, including invading host cells where they can replicate in a protected intracellular niche. Protein S-palmitoylation is a dynamic post-translational modification in which the fatty acid palmitate is covalently linked to cysteine residues on proteins by the enzyme palmitoyl acyltransferase (PAT) and can be removed by lysosomal palmitoyl-protein thioesterase (PPT) or cytosolic acyl-protein thioesterase (APT). In addition to anchoring proteins to intracellular membranes, functions of dynamic palmitoylation include - targeting proteins to specific intracellular compartments via trafficking pathways, regulating the cycling of proteins between membranes, modulating protein function and regulating protein stability. Recent studies in the eukaryotic parasites - Plasmodium falciparum, Toxoplasma gondii, Trypanosoma brucei, Cryptococcus neoformans and Giardia lamblia - have identified large families of PATs and palmitoylated proteins. Many palmitoylated proteins are important for diverse aspects of pathogenesis, including differentiation into infective life cycle stages, biogenesis and tethering of secretory organelles, assembling the machinery powering motility and targeting virulence factors to the plasma membrane. This review aims to summarize our current knowledge of palmitoylation in eukaryotic parasites, highlighting five exemplary mechanisms of parasite virulence dependent on palmitoylation.
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Affiliation(s)
- Robert W B Brown
- a Department of Pathology and Laboratory Medicine , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - Aabha I Sharma
- b Departments of Pathology and Microbiology-Immunology , Northwestern University , Chicago , IL , USA
| | - David M Engman
- a Department of Pathology and Laboratory Medicine , Cedars-Sinai Medical Center , Los Angeles , CA , USA
- b Departments of Pathology and Microbiology-Immunology , Northwestern University , Chicago , IL , USA
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13
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New developments in probing and targeting protein acylation in malaria, leishmaniasis and African sleeping sickness. Parasitology 2017; 145:157-174. [PMID: 28270257 DOI: 10.1017/s0031182017000282] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Infections by protozoan parasites, such as Plasmodium falciparum or Leishmania donovani, have a significant health, social and economic impact and threaten billions of people living in tropical and sub-tropical regions of developing countries worldwide. The increasing range of parasite strains resistant to frontline therapeutics makes the identification of novel drug targets and the development of corresponding inhibitors vital. Post-translational modifications (PTMs) are important modulators of biology and inhibition of protein lipidation has emerged as a promising therapeutic strategy for treatment of parasitic diseases. In this review we summarize the latest insights into protein lipidation in protozoan parasites. We discuss how recent chemical proteomic approaches have delivered the first global overviews of protein lipidation in these organisms, contributing to our understanding of the role of this PTM in critical metabolic and cellular functions. Additionally, we highlight the development of new small molecule inhibitors to target parasite acyl transferases.
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14
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Roberts AJ, Fairlamb AH. The N-myristoylome of Trypanosoma cruzi. Sci Rep 2016; 6:31078. [PMID: 27492267 PMCID: PMC4974623 DOI: 10.1038/srep31078] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 07/12/2016] [Indexed: 01/04/2023] Open
Abstract
Protein N-myristoylation is catalysed by N-myristoyltransferase (NMT), an essential and druggable target in Trypanosoma cruzi, the causative agent of Chagas' disease. Here we have employed whole cell labelling with azidomyristic acid and click chemistry to identify N-myristoylated proteins in different life cycle stages of the parasite. Only minor differences in fluorescent-labelling were observed between the dividing forms (the insect epimastigote and mammalian amastigote stages) and the non-dividing trypomastigote stage. Using a combination of label-free and stable isotope labelling of cells in culture (SILAC) based proteomic strategies in the presence and absence of the NMT inhibitor DDD85646, we identified 56 proteins enriched in at least two out of the three experimental approaches. Of these, 6 were likely to be false positives, with the remaining 50 commencing with amino acids MG at the N-terminus in one or more of the T. cruzi genomes. Most of these are proteins of unknown function (32), with the remainder (18) implicated in a diverse range of critical cellular and metabolic functions such as intracellular transport, cell signalling and protein turnover. In summary, we have established that 0.43-0.46% of the proteome is N-myristoylated in T. cruzi approaching that of other eukaryotic organisms (0.5-1.7%).
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Affiliation(s)
- Adam J. Roberts
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Alan H. Fairlamb
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
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15
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Sanchez MA, Tran KD, Valli J, Hobbs S, Johnson E, Gluenz E, Landfear SM. KHARON Is an Essential Cytoskeletal Protein Involved in the Trafficking of Flagellar Membrane Proteins and Cell Division in African Trypanosomes. J Biol Chem 2016; 291:19760-73. [PMID: 27489106 DOI: 10.1074/jbc.m116.739235] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 11/06/2022] Open
Abstract
African trypanosomes and related kinetoplastid parasites selectively traffic specific membrane proteins to the flagellar membrane, but the mechanisms for this trafficking are poorly understood. We show here that KHARON, a protein originally identified in Leishmania parasites, interacts with a putative trypanosome calcium channel and is required for its targeting to the flagellar membrane. KHARON is located at the base of the flagellar axoneme, where it likely mediates targeting of flagellar membrane proteins, but is also on the subpellicular microtubules and the mitotic spindle. Hence, KHARON is probably a multifunctional protein that associates with several components of the trypanosome cytoskeleton. RNA interference-mediated knockdown of KHARON mRNA results in failure of the calcium channel to enter the flagellar membrane, detachment of the flagellum from the cell body, and disruption of mitotic spindles. Furthermore, knockdown of KHARON mRNA induces a lethal failure of cytokinesis in both bloodstream (mammalian host) and procyclic (insect vector) life cycle stages, and KHARON is thus critical for parasite viability.
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Affiliation(s)
- Marco A Sanchez
- From the Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, Oregon 97239 and
| | - Khoa D Tran
- From the Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, Oregon 97239 and
| | - Jessica Valli
- the Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Sam Hobbs
- From the Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, Oregon 97239 and
| | - Errin Johnson
- the Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Eva Gluenz
- the Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Scott M Landfear
- From the Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, Oregon 97239 and
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16
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Wright MH, Paape D, Price HP, Smith DF, Tate EW. Global Profiling and Inhibition of Protein Lipidation in Vector and Host Stages of the Sleeping Sickness Parasite Trypanosoma brucei. ACS Infect Dis 2016; 2:427-441. [PMID: 27331140 PMCID: PMC4906374 DOI: 10.1021/acsinfecdis.6b00034] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Indexed: 01/05/2023]
Abstract
The enzyme N-myristoyltransferase (NMT) catalyzes the essential fatty acylation of substrate proteins with myristic acid in eukaryotes and is a validated drug target in the parasite Trypanosoma brucei, the causative agent of African trypanosomiasis (sleeping sickness). N-Myristoylation typically mediates membrane localization of proteins and is essential to the function of many. However, only a handful of proteins are experimentally validated as N-myristoylated in T. brucei. Here, we perform metabolic labeling with an alkyne-tagged myristic acid analogue, enabling the capture of lipidated proteins in insect and host life stages of T. brucei. We further compare this with a longer chain palmitate analogue to explore the chain length-specific incorporation of fatty acids into proteins. Finally, we combine the alkynyl-myristate analogue with NMT inhibitors and quantitative chemical proteomics to globally define N-myristoylated proteins in the clinically relevant bloodstream form parasites. This analysis reveals five ARF family small GTPases, calpain-like proteins, phosphatases, and many uncharacterized proteins as substrates of NMT in the parasite, providing a global view of the scope of this important protein modification and further evidence for the crucial and pleiotropic role of NMT in the cell.
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Affiliation(s)
- Megan H. Wright
- Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
| | - Daniel Paape
- Centre for Immunology and Infection, Department
of Biology, University of York, York YO10 5DD, United Kingdom
| | - Helen P. Price
- Centre for Immunology and Infection, Department
of Biology, University of York, York YO10 5DD, United Kingdom
| | - Deborah F. Smith
- Centre for Immunology and Infection, Department
of Biology, University of York, York YO10 5DD, United Kingdom
| | - Edward W. Tate
- Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
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17
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Cos-Seq for high-throughput identification of drug target and resistance mechanisms in the protozoan parasite Leishmania. Proc Natl Acad Sci U S A 2016; 113:E3012-21. [PMID: 27162331 DOI: 10.1073/pnas.1520693113] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Innovative strategies are needed to accelerate the identification of antimicrobial drug targets and resistance mechanisms. Here we develop a sensitive method, which we term Cosmid Sequencing (or "Cos-Seq"), based on functional cloning coupled to next-generation sequencing. Cos-Seq identified >60 loci in the Leishmania genome that were enriched via drug selection with methotrexate and five major antileishmanials (antimony, miltefosine, paromomycin, amphotericin B, and pentamidine). Functional validation highlighted both known and previously unidentified drug targets and resistance genes, including novel roles for phosphatases in resistance to methotrexate and antimony, for ergosterol and phospholipid metabolism genes in resistance to miltefosine, and for hypothetical proteins in resistance to paromomycin, amphothericin B, and pentamidine. Several genes/loci were also found to confer resistance to two or more antileishmanials. This screening method will expedite the discovery of drug targets and resistance mechanisms and is easily adaptable to other microorganisms.
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18
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Herrera LJ, Brand S, Santos A, Nohara LL, Harrison J, Norcross NR, Thompson S, Smith V, Lema C, Varela-Ramirez A, Gilbert IH, Almeida IC, Maldonado RA. Validation of N-myristoyltransferase as Potential Chemotherapeutic Target in Mammal-Dwelling Stages of Trypanosoma cruzi. PLoS Negl Trop Dis 2016; 10:e0004540. [PMID: 27128971 PMCID: PMC4851402 DOI: 10.1371/journal.pntd.0004540] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 02/22/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Trypanosoma cruzi causes Chagas disease, an endemic and debilitating illness in Latin America. Lately, owing to extensive population movements, this neglected tropical disease has become a global health concern. The two clinically available drugs for the chemotherapy of Chagas disease have rather high toxicity and limited efficacy in the chronic phase of the disease, and may induce parasite resistance. The development of new anti-T. cruzi agents is therefore imperative. The enzyme N-myristoyltransferase (NMT) has recently been biochemically characterized, shown to be essential in Leishmania major, Trypanosoma brucei, and T. cruzi¸ and proposed as promising chemotherapeutic target in these trypanosomatids. METHODOLOGY/PRINCIPAL FINDINGS Here, using high-content imaging we assayed eight known trypanosomatid NMT inhibitors, against mammal-dwelling intracellular amastigote and trypomastigote stages and demonstrated that three of them (compounds 1, 5, and 8) have potent anti-proliferative effect at submicromolar concentrations against T. cruzi, with very low toxicity against human epithelial cells. Moreover, metabolic labeling using myristic acid, azide showed a considerable decrease in the myristoylation of proteins in parasites treated with NMT inhibitors, providing evidence of the on-target activity of the inhibitors. CONCLUSIONS/SIGNIFICANCE Taken together, our data point out to the potential use of NMT inhibitors as anti-T. cruzi chemotherapy.
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Affiliation(s)
- Linda J. Herrera
- The Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - Stephen Brand
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Sir James Black Centre, Dundee, United Kingdom
| | - Andres Santos
- The Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - Lilian L. Nohara
- The Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - Justin Harrison
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Sir James Black Centre, Dundee, United Kingdom
| | - Neil R. Norcross
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Sir James Black Centre, Dundee, United Kingdom
| | - Stephen Thompson
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Sir James Black Centre, Dundee, United Kingdom
| | - Victoria Smith
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Sir James Black Centre, Dundee, United Kingdom
| | - Carolina Lema
- The Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - Armando Varela-Ramirez
- The Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - Ian H. Gilbert
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Sir James Black Centre, Dundee, United Kingdom
| | - Igor C. Almeida
- The Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - Rosa A. Maldonado
- The Border Biomedical Research Center, Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
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19
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Landfear SM, Tran KD, Sanchez MA. Flagellar membrane proteins in kinetoplastid parasites. IUBMB Life 2015; 67:668-76. [PMID: 26599841 DOI: 10.1002/iub.1411] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 11/06/2022]
Abstract
All kinetoplastid parasites, including protozoa such as Leishmania species, Trypanosoma brucei, and Trypanosoma cruzi that cause devastating diseases in humans and animals, are flagellated throughout their life cycles. Although flagella were originally thought of primarily as motility organelles, flagellar functions in other critical processes, especially in sensing and signal transduction, have become more fully appreciated in the recent past. The flagellar membrane is a highly specialized subdomain of the surface membrane, and flagellar membrane proteins are likely to be critical components for all the biologically important roles of flagella. In this review, we summarize recent discoveries relevant to flagellar membrane proteins in these parasites, including the identification of such proteins, investigation of their biological functions, and mechanisms of selective trafficking to the flagellar membrane. Prospects for future investigations and current unsolved problems are highlighted.
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Affiliation(s)
- Scott M Landfear
- Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, OR, USA
| | - Khoa D Tran
- Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, OR, USA
| | - Marco A Sanchez
- Department of Molecular Microbiology and Immunology, Oregon Health and Sciences University, Portland, OR, USA
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20
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Albisetti A, Wiese S, Schneider A, Niemann M. A component of the mitochondrial outer membrane proteome of T. brucei probably contains covalent bound fatty acids. Exp Parasitol 2015; 155:49-57. [PMID: 25982029 DOI: 10.1016/j.exppara.2015.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 03/30/2015] [Accepted: 05/11/2015] [Indexed: 11/24/2022]
Abstract
A subclass of eukaryotic proteins is subject to modification with fatty acids, the most common of which are palmitic and myristic acid. Protein acylation allows association with cellular membranes in the absence of transmembrane domains. Here we examine POMP39, a protein previously described to be present in the outer mitochondrial membrane proteome (POMP) of the protozoan parasite Trypanosoma brucei. POMP39 lacks canonical transmembrane domains, but is likely both myristoylated and palmitoylated on its N-terminus. Interestingly, the protein is also dually localized on the surface of the mitochondrion as well as in the flagellum of both insect-stage and the bloodstream form of the parasites. Upon abolishing of global protein acylation or mutation of the myristoylation site, POMP39 relocates to the cytosol. RNAi-mediated ablation of the protein neither causes a growth phenotype in insect-stage nor bloodstream form trypanosomes.
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Affiliation(s)
- Anna Albisetti
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern 3012, Switzerland
| | - Sebastian Wiese
- Core Unit Mass Spectrometry and Proteomics, Medical Faculty, University of Ulm, Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern 3012, Switzerland
| | - Moritz Niemann
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern 3012, Switzerland.
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21
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Ca2+ Regulation of Trypanosoma brucei Phosphoinositide Phospholipase C. EUKARYOTIC CELL 2015; 14:486-94. [PMID: 25769297 DOI: 10.1128/ec.00019-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Accepted: 03/09/2015] [Indexed: 11/20/2022]
Abstract
We characterized a phosphoinositide phospholipase C (PI-PLC) from the procyclic form (PCF) of Trypanosoma brucei. The protein contains a domain organization characteristic of typical PI-PLCs, such as X and Y catalytic domains, an EF-hand calcium-binding motif, and a C2 domain, but it lacks a pleckstrin homology (PH) domain. In addition, the T. brucei PI-PLC (TbPI-PLC) contains an N-terminal myristoylation consensus sequence found only in trypanosomatid PI-PLCs. A peptide containing this N-terminal domain fused to green fluorescent protein (GFP) was targeted to the plasma membrane. TbPI-PLC enzymatic activity was stimulated by Ca(2+) concentrations below the cytosolic levels in the parasite, suggesting that the enzyme is constitutively active. TbPI-PLC hydrolyzes both phosphatidylinositol (PI) and phosphatidylinositol 4,5-bisphosphate (PIP2), with a higher affinity for PIP2. We found that modification of a single amino acid in the EF-hand motif greatly affected the protein's Ca(2+) sensitivity and substrate preference, demonstrating the role of this motif in Ca(2+) regulation of TbPI-PLC. Endogenous TbPI-PLC localizes to intracellular vesicles and might be using an intracellular source of PIP2. Knockdown of TbPI-PLC expression by RNA interference (RNAi) did not result in growth inhibition, although enzymatic activity was still present in parasites, resulting in hydrolysis of PIP2 and a contribution to the inositol 1,4,5-trisphosphate (IP3)/diacylglycerol (DAG) pathway.
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22
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Wright MH, Paape D, Storck EM, Serwa RA, Smith DF, Tate EW. Global analysis of protein N-myristoylation and exploration of N-myristoyltransferase as a drug target in the neglected human pathogen Leishmania donovani. ACTA ACUST UNITED AC 2015; 22:342-54. [PMID: 25728269 PMCID: PMC4372256 DOI: 10.1016/j.chembiol.2015.01.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 12/16/2014] [Accepted: 01/13/2015] [Indexed: 10/26/2022]
Abstract
N-Myristoyltransferase (NMT) modulates protein function through the attachment of the lipid myristate to the N terminus of target proteins, and is a promising drug target in eukaryotic parasites such as Leishmania donovani. Only a small number of NMT substrates have been characterized in Leishmania, and a global picture of N-myristoylation is lacking. Here, we use metabolic tagging with an alkyne-functionalized myristic acid mimetic in live parasites followed by downstream click chemistry and analysis to identify lipidated proteins in both the promastigote (extracellular) and amastigote (intracellular) life stages. Quantitative chemical proteomics is used to profile target engagement by NMT inhibitors, and to define the complement of N-myristoylated proteins. Our results provide new insight into the multiple pathways modulated by NMT and the pleiotropic effects of NMT inhibition. This work constitutes the first global experimental analysis of protein lipidation in Leishmania, and reveals the extent of NMT-related biology yet to be explored for this neglected human pathogen.
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Affiliation(s)
- Megan H Wright
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.
| | - Daniel Paape
- Centre for Immunology and Infection, Department of Biology, University of York, York YO10 5DD, UK
| | | | - Remigiusz A Serwa
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - Deborah F Smith
- Centre for Immunology and Infection, Department of Biology, University of York, York YO10 5DD, UK
| | - Edward W Tate
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.
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A target repurposing approach identifies N-myristoyltransferase as a new candidate drug target in filarial nematodes. PLoS Negl Trop Dis 2014; 8:e3145. [PMID: 25188325 PMCID: PMC4154664 DOI: 10.1371/journal.pntd.0003145] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 07/25/2014] [Indexed: 11/19/2022] Open
Abstract
Myristoylation is a lipid modification involving the addition of a 14-carbon unsaturated fatty acid, myristic acid, to the N-terminal glycine of a subset of proteins, a modification that promotes their binding to cell membranes for varied biological functions. The process is catalyzed by myristoyl-CoA:protein N-myristoyltransferase (NMT), an enzyme which has been validated as a drug target in human cancers, and for infectious diseases caused by fungi, viruses and protozoan parasites. We purified Caenorhabditis elegans and Brugia malayi NMTs as active recombinant proteins and carried out kinetic analyses with their essential fatty acid donor, myristoyl-CoA and peptide substrates. Biochemical and structural analyses both revealed that the nematode enzymes are canonical NMTs, sharing a high degree of conservation with protozoan NMT enzymes. Inhibitory compounds that target NMT in protozoan species inhibited the nematode NMTs with IC50 values of 2.5–10 nM, and were active against B. malayi microfilariae and adult worms at 12.5 µM and 50 µM respectively, and C. elegans (25 µM) in culture. RNA interference and gene deletion in C. elegans further showed that NMT is essential for nematode viability. The effects observed are likely due to disruption of the function of several downstream target proteins. Potential substrates of NMT in B. malayi are predicted using bioinformatic analysis. Our genetic and chemical studies highlight the importance of myristoylation in the synthesis of functional proteins in nematodes and have shown for the first time that NMT is required for viability in parasitic nematodes. These results suggest that targeting NMT could be a valid approach for the development of chemotherapeutic agents against nematode diseases including filariasis. Lymphatic filariasis and onchocerciasis are neglected tropical diseases caused by filarial nematodes. The limitations of existing drugs to treat these infections highlight the need for new drugs. In the present study, we investigated myristoylation, a lipid modification of a subset of proteins that promotes their binding to cell membranes for varied biological functions. The process is catalyzed by N-myristoyltransferase (NMT), an enzyme which has been validated as a drug target in protozoan parasites. We performed kinetic analyses on Caenorhabditis elegans and Brugia malayi NMTs. NMT inhibitors were active against B. malayi microfilariae and adult worms, and C. elegans in culture. RNA interference and gene deletion in C. elegans further demonstrated that NMT is essential for nematode viability. Our genetic and chemical studies indicate the importance of myristoylation in the synthesis of functional proteins in nematodes and have shown for the first time that NMT is required for viability in parasitic nematodes. These results suggest that targeting NMT could be a valid approach for the development of new therapies against nematode infection including filarial diseases.
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24
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Recent Advances in The Discovery ofN-Myristoyltransferase Inhibitors. ChemMedChem 2014; 9:2425-37. [DOI: 10.1002/cmdc.201402174] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 07/17/2014] [Indexed: 01/08/2023]
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25
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Goldston AM, Sharma AI, Paul KS, Engman DM. Acylation in trypanosomatids: an essential process and potential drug target. Trends Parasitol 2014; 30:350-60. [PMID: 24954795 DOI: 10.1016/j.pt.2014.05.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 05/06/2014] [Accepted: 05/06/2014] [Indexed: 12/11/2022]
Abstract
Fatty acylation--the addition of fatty acid moieties such as myristate and palmitate to proteins--is essential for the survival, growth, and infectivity of the trypanosomatids: Trypanosoma brucei, Trypanosoma cruzi, and Leishmania. Myristoylation and palmitoylation are critical for parasite growth, targeting and localization, and the intrinsic function of some proteins. The trypanosomatids possess a single N-myristoyltransferase (NMT) and multiple palmitoyl acyltransferases, and these enzymes and their protein targets are only now being characterized. Global inhibition of either process leads to cell death in trypanosomatids, and genetic ablation of NMT compromises virulence. Moreover, NMT inhibitors effectively cure T. brucei infection in rodents. Thus, protein acylation represents an attractive target for the development of new trypanocidal drugs.
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Affiliation(s)
- Amanda M Goldston
- Departments of Pathology and Microbiology-Immunology, Northwestern University, Chicago, Illinois, USA
| | - Aabha I Sharma
- Departments of Pathology and Microbiology-Immunology, Northwestern University, Chicago, Illinois, USA
| | - Kimberly S Paul
- Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina, USA
| | - David M Engman
- Departments of Pathology and Microbiology-Immunology, Northwestern University, Chicago, Illinois, USA.
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26
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Roberts A, Torrie L, Wyllie S, Fairlamb A. Biochemical and genetic characterization of Trypanosoma cruzi N-myristoyltransferase. Biochem J 2014; 459:323-32. [PMID: 24444291 PMCID: PMC3969225 DOI: 10.1042/bj20131033] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 01/20/2014] [Accepted: 01/21/2014] [Indexed: 12/20/2022]
Abstract
Co- and post-translational N-myristoylation is known to play a role in the correct subcellular localization of specific proteins in eukaryotes. The enzyme that catalyses this reaction, NMT (N-myristoyltransferase), has been pharmacologically validated as a drug target in the African trypanosome, Trypanosoma brucei. In the present study, we evaluate NMT as a potential drug target in Trypanosoma cruzi, the causative agent of Chagas' disease, using chemical and genetic approaches. Replacement of both allelic copies of TcNMT (T. cruzi NMT) was only possible in the presence of a constitutively expressed ectopic copy of the gene, indicating that this gene is essential for survival of T. cruzi epimastigotes. The pyrazole sulphonamide NMT inhibitor DDD85646 is 13-23-fold less potent against recombinant TcNMT than TbNMT (T. brucei NMT), with Ki values of 12.7 and 22.8 nM respectively, by scintillation proximity or coupled assay methods. DDD85646 also inhibits growth of T. cruzi epimastigotes (EC50=6.9 μM), but is ~1000-fold less potent than that reported for T. brucei. On-target activity is demonstrated by shifts in cell potency in lines that over- and under-express NMT and by inhibition of intracellular N-myristoylation of several proteins in a dose-dependent manner. Collectively, our findings suggest that N-myristoylation is an essential and druggable target in T. cruzi.
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Key Words
- chagas’ disease
- click chemistry
- drug target
- n-myristoylation
- trypanosoma cruzi
- validation
- cap5.5, cytoskeleton-associated protein 5.5
- dig, digoxigenin
- dko, double knockout
- dmem, dulbecco’s modified eagle’s medium
- hyg, hygromycin phosphotransferase
- nmt, n-myristoyltransferase
- nmtoe, nmt overexpressor
- pac, puromycin n-acetyltransferase
- rth/fbs, rpmi 1640 medium supplemented with trypticase, haemin, hepes and 10% heat-inactivated fbs
- sko, single knockout
- tbnmt, trypanosoma brucei nmt
- tcep, tris-(2-carboxyethyl)phosphine
- tcnmt, trypanosoma cruzi nmt
- tctryr, trypanosoma cruzi trypanothione reductase
- wt, wild-type
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Affiliation(s)
- Adam J. Roberts
- *Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Leah S. Torrie
- *Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Susan Wyllie
- *Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Alan H. Fairlamb
- *Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
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Tate EW, Bell AS, Rackham MD, Wright MH. N-Myristoyltransferase as a potential drug target in malaria and leishmaniasis. Parasitology 2014; 141:37-49. [PMID: 23611109 DOI: 10.1017/s0031182013000450] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Infections caused by protozoan parasites are among the most widespread and intractable transmissible diseases affecting the developing world, with malaria and leishmaniasis being the most costly in terms of morbidity and mortality. Although new drugs are urgently required against both diseases in the face of ever-rising resistance to frontline therapies, very few candidates passing through development pipelines possess a known and novel mode of action. Set in the context of drugs currently in use and under development, we present the evidence for N-myristoyltransferase (NMT), an enzyme that N-terminally lipidates a wide range of specific target proteins through post-translational modification, as a potential drug target in malaria and the leishmaniases. We discuss the limitations of current knowledge regarding the downstream targets of this enzyme in protozoa, and our recent progress towards potent cell-active NMT inhibitors against the most clinically-relevant species of parasite. Finally, we outline the next steps required in terms of both tools to understand N-myristoylation in protozoan parasites, and the generation of potential development candidates based on the output of our recently-reported high-throughput screens.
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Affiliation(s)
- Edward W Tate
- Department of Chemistry, Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Andrew S Bell
- Department of Chemistry, Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Mark D Rackham
- Department of Chemistry, Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Megan H Wright
- Department of Chemistry, Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
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Identification of protein complex associated with LYT1 of Trypanosoma cruzi. BIOMED RESEARCH INTERNATIONAL 2013; 2013:493525. [PMID: 23586042 PMCID: PMC3613072 DOI: 10.1155/2013/493525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 12/21/2012] [Accepted: 12/24/2012] [Indexed: 01/19/2023]
Abstract
To carry out the intracellular phase of its life cycle, Trypanosoma cruzi must infect a host cell. Although a few molecules have been reported to participate in this process, one known protein is LYT1, which promotes lysis under acidic conditions and is involved in parasite infection and development. Alternative transcripts from a single LYT1 gene generate two proteins with differential functions and compartmentalization. Single-gene products targeted to more than one location can interact with disparate proteins that might affect their function and targeting properties. The aim of this work was to study the LYT1 interaction map using coimmunoprecipitation assays with transgenic parasites expressing LYT1 products fused to GFP. We detected several proteins of sizes from 8 to 150 kDa that bind to LYT1 with different binding strengths. By MS-MS analysis, we identified proteins involved in parasite infectivity (trans-sialidase), development (kDSPs and histones H2A and H2B), and motility and protein traffic (dynein and α - and β -tubulin), as well as protein-protein interactions (TPR-protein and kDSPs) and several hypothetical proteins. Our approach led us to identify the LYT1 interaction profile, thereby providing insights into the molecular mechanisms that contribute to parasite stage development and pathogenesis of T. cruzi infection.
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29
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Abstract
SIGNIFICANCE Cysteine residues of proteins participate in the catalysis of biochemical reactions, are crucial for redox reactions, and influence protein structure by the formation of disulfide bonds. Covalent posttranslational modifications (PTMs) of cysteine residues are important mediators of redox regulation and signaling by coupling protein activity to the cellular redox state, and moreover influence stability, function, and localization of proteins. A diverse group of protozoan and metazoan parasites are a major cause of diseases in humans, such as malaria, African trypanosomiasis, leishmaniasis, toxoplasmosis, filariasis, and schistosomiasis. RECENT ADVANCES Human parasites undergo dramatic morphological and metabolic changes while they pass complex life cycles and adapt to changing environments in host and vector. These processes are in part regulated by PTMs of parasitic proteins. In human parasites, posttranslational cysteine modifications are involved in crucial cellular events such as signal transduction (S-glutathionylation and S-nitrosylation), redox regulation of proteins (S-glutathionylation and S-nitrosylation), protein trafficking and subcellular localization (palmitoylation and prenylation), as well as invasion into and egress from host cells (palmitoylation). This review focuses on the occurrence and mechanisms of these cysteine modifications in parasites. CRITICAL ISSUES Studies on cysteine modifications in human parasites are so far largely based on in vitro experiments. FUTURE DIRECTIONS The in vivo regulation of cysteine modifications and their role in parasite development will be of great interest in order to understand redox signaling in parasites.
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Affiliation(s)
- Esther Jortzik
- Interdisciplinary Research Center, Justus Liebig University, Giessen, Germany
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30
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Acylation-dependent and-independent membrane targeting and distinct functions of small myristoylated proteins (SMPs) in Leishmania major. Int J Parasitol 2012; 42:239-47. [DOI: 10.1016/j.ijpara.2011.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 11/20/2022]
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31
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Maclean LM, O'Toole PJ, Stark M, Marrison J, Seelenmeyer C, Nickel W, Smith DF. Trafficking and release of Leishmania metacyclic HASPB on macrophage invasion. Cell Microbiol 2012; 14:740-61. [PMID: 22256896 PMCID: PMC3491706 DOI: 10.1111/j.1462-5822.2012.01756.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Proteins of the Leishmania hydrophilic acylated surface protein B (HASPB) family are only expressed in infective parasites (both extra- and intracellular stages) and, together with the peripheral membrane protein SHERP (small hydrophilic endoplasmic reticulum-associated protein), are essential for parasite differentiation (metacyclogenesis) in the sand fly vector. HASPB is a ‘non-classically’ secreted protein, requiring N-terminal acylation for trafficking to and exposure on the plasma membrane. Here, we use live cell imaging methods to further explore this pathway to the membrane and flagellum. Unlike HASPB trafficking in transfected mammalian cells, we find no evidence for a phosphorylation-regulated recycling pathway in metacyclic parasites. Once at the plasma membrane, HASPB18–GFP (green fluorescent protein) can undergo bidirectional movement within the inner leaflet of the membrane and on the flagellum. Transfer of fluorescent protein between the flagellum and the plasma membrane is compromised, however, suggesting the presence of a diffusion barrier at the base of the Leishmania flagellum. Full-length HASPB is released from the metacyclic parasite surface on to macrophages during phagocytosis but while expression is maintained in intracellular amastigotes, HASPB cannot be detected on the external surface in these cells. Thus HASPB may be a dual function protein that is shed by the infective metacyclic but retained internally once Leishmania are taken up by macrophages.
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Affiliation(s)
- Lorna M Maclean
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York YO10 5DD, UK
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32
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Price HP, Hodgkinson MR, Curwen RS, MacLean LM, Brannigan JA, Carrington M, Smith BA, Ashford DA, Stark M, Smith DF. The orthologue of Sjögren's syndrome nuclear autoantigen 1 (SSNA1) in Trypanosoma brucei is an immunogenic self-assembling molecule. PLoS One 2012; 7:e31842. [PMID: 22363749 PMCID: PMC3282761 DOI: 10.1371/journal.pone.0031842] [Citation(s) in RCA: 12] [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: 11/28/2011] [Accepted: 01/12/2012] [Indexed: 11/18/2022] Open
Abstract
Primary Sjögren's Syndrome (PSS) is a highly prevalent autoimmune disease, typically manifesting as lymphocytic infiltration of the exocrine glands leading to chronically impaired lacrimal and salivary secretion. Sjögren's Syndrome nuclear autoantigen 1 (SSNA1 or NA14) is a major specific target for autoantibodies in PSS but the precise function and clinical relevance of this protein are largely unknown. Orthologues of the gene are absent from many of the commonly used model organisms but are present in Chlamyodomonas reinhardtii (in which it has been termed DIP13) and most protozoa. We report the functional characterisation of the orthologue of SSNA1 in the kinetoplastid parasite, Trypanosoma brucei. Both TbDIP13 and human SSNA1 are small coiled-coil proteins which are predicted to be remote homologues of the actin-binding protein tropomyosin. We use comparative proteomic methods to identify potential interacting partners of TbDIP13. We also show evidence that TbDIP13 is able to self-assemble into fibril-like structures both in vitro and in vivo, a property which may contribute to its immunogenicity. Endogenous TbDIP13 partially co-localises with acetylated α-tubulin in the insect procyclic stage of the parasite. However, deletion of the DIP13 gene in cultured bloodstream and procyclic stages of T. brucei has little effect on parasite growth or morphology, indicating either a degree of functional redundancy or a function in an alternative stage of the parasite life cycle.
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Affiliation(s)
- Helen P Price
- Centre for Immunology and Infection, Department of Biology, University of York, Heslington, York, United Kingdom.
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33
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Kramer S. Developmental regulation of gene expression in the absence of transcriptional control: The case of kinetoplastids. Mol Biochem Parasitol 2012; 181:61-72. [PMID: 22019385 DOI: 10.1016/j.molbiopara.2011.10.002] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 10/03/2011] [Accepted: 10/04/2011] [Indexed: 11/25/2022]
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34
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Proto WR, Castanys-Munoz E, Black A, Tetley L, Moss CX, Juliano L, Coombs GH, Mottram JC. Trypanosoma brucei metacaspase 4 is a pseudopeptidase and a virulence factor. J Biol Chem 2011; 286:39914-25. [PMID: 21949125 PMCID: PMC3220528 DOI: 10.1074/jbc.m111.292334] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Metacaspases are caspase family cysteine peptidases found in plants, fungi, and protozoa but not mammals. Trypanosoma brucei is unusual in having five metacaspases (MCA1-MCA5), of which MCA1 and MCA4 have active site substitutions, making them possible non-enzymatic homologues. Here we demonstrate that recombinant MCA4 lacks detectable peptidase activity despite maintaining a functional peptidase structure. MCA4 is expressed primarily in the bloodstream form of the parasite and associates with the flagellar membrane via dual myristoylation/palmitoylation. Loss of function phenotyping revealed critical roles for MCA4; rapid depletion by RNAi caused lethal disruption to the parasite's cell cycle, yet the generation of MCA4 null mutant parasites (Δmca4) was possible. Δmca4 had normal growth in axenic culture but markedly reduced virulence in mice. Further analysis revealed that MCA4 is released from the parasite and is specifically processed by MCA3, the only metacaspase that is both palmitoylated and enzymatically active. Accordingly, we have identified that the multiple metacaspases in T. brucei form a membrane-associated proteolytic cascade to generate a pseudopeptidase virulence factor.
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Affiliation(s)
- William R Proto
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary, and Life Sciences, University of Glasgow, 120 University Place, Glasgow G12 8TA, United Kingdom
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35
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Maric D, McGwire BS, Buchanan KT, Olson CL, Emmer BT, Epting CL, Engman DM. Molecular determinants of ciliary membrane localization of Trypanosoma cruzi flagellar calcium-binding protein. J Biol Chem 2011; 286:33109-17. [PMID: 21784841 DOI: 10.1074/jbc.m111.240895] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The flagellar calcium-binding protein (FCaBP) of Trypanosoma cruzi is localized to the flagellar membrane in all life cycle stages of the parasite. Myristoylation and palmitoylation of the N terminus of FCaBP are necessary for flagellar membrane targeting. Not all dually acylated proteins in T. cruzi are flagellar, however. Other determinants of FCaBP therefore likely contribute to flagellar specificity. We generated T. cruzi transfectants expressing the N-terminal 24 or 12 amino acids of FCaBP fused to GFP. Analysis of these mutants revealed that although amino acids 1-12 are sufficient for dual acylation and membrane binding, amino acids 13-24 are required for flagellar specificity and lipid raft association. Mutagenesis of several conserved lysine residues in the latter peptide demonstrated that these residues are essential for flagellar targeting and lipid raft association. Finally, FCaBP was expressed in the protozoan Leishmania amazonensis, which lacks FCaBP. The flagellar localization and membrane association of FCaBP in L. amazonensis suggest that the mechanisms for flagellar targeting, including a specific palmitoyl acyltransferase, are conserved in this organism.
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Affiliation(s)
- Danijela Maric
- Department of Pathology, Northwestern University, Chicago, Illinois 60611, USA
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36
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Global analysis of protein palmitoylation in African trypanosomes. EUKARYOTIC CELL 2010; 10:455-63. [PMID: 21193548 DOI: 10.1128/ec.00248-10] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many eukaryotic proteins are posttranslationally modified by the esterification of cysteine thiols to long-chain fatty acids. This modification, protein palmitoylation, is catalyzed by a large family of palmitoyl acyltransferases that share an Asp-His-His-Cys Cys-rich domain but differ in their subcellular localizations and substrate specificities. In Trypanosoma brucei, the flagellated protozoan parasite that causes African sleeping sickness, protein palmitoylation has been observed for a few proteins, but the extent and consequences of this modification are largely unknown. We undertook the present study to investigate T. brucei protein palmitoylation at both the enzyme and substrate levels. Treatment of parasites with an inhibitor of total protein palmitoylation caused potent growth inhibition, yet there was no effect on growth by the separate, selective inhibition of each of the 12 individual T. brucei palmitoyl acyltransferases. This suggested either that T. brucei evolved functional redundancy for the palmitoylation of essential palmitoyl proteins or that palmitoylation of some proteins is catalyzed by a noncanonical transferase. To identify the palmitoylated proteins in T. brucei, we performed acyl biotin exchange chemistry on parasite lysates, followed by streptavidin chromatography, two-dimensional liquid chromatography-tandem mass spectrometry protein identification, and QSpec statistical analysis. A total of 124 palmitoylated proteins were identified, with an estimated false discovery rate of 1.0%. This palmitoyl proteome includes all of the known palmitoyl proteins in procyclic-stage T. brucei as well as several proteins whose homologues are palmitoylated in other organisms. Their sequences demonstrate the variety of substrate motifs that support palmitoylation, and their identities illustrate the range of cellular processes affected by palmitoylation in these important pathogens.
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Abstract
The Arf-like (Arl) small GTPases have a diverse range of functions in the eukaryotic cell. Metazoan Arl2 acts as a regulator of microtubule biogenesis, binding to the tubulin-specific chaperone cofactor D. Arl2 also has a mitochondrial function through its interactions with BART and ANT-1, the only member of the Ras superfamily to be found in this organelle to date. In the present study, we describe characterization of the Arl2 orthologue in the protozoan parasite Trypanosoma brucei. Modulation of TbARL2 expression in bloodstream form parasites by RNA interference (RNAi) causes inhibition of cleavage furrow formation, resulting in a severe defect in cytokinesis and the accumulation of multinucleated cells. RNAi of TbARL2 also results in loss of acetylated alpha-tubulin but not of total -tubulin from cellular microtubules. While overexpression of TbARL2(myc) also leads to a defect in cytokinesis, an excess of untagged protein has no effect on cell division, demonstrating the importance of the extreme C-terminus in correct function. TbARL2 overexpressing cells (either myc-tagged or untagged) have an increase in acetylated -tubulin. Our data indicate that Arl2 has a fundamentally conserved role in trypanosome microtubule biogenesis that correlates with -tubulin acetylation.
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38
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Kutuzov MA, Bennett N, Andreeva AV. Protein phosphatase with EF-hand domains 2 (PPEF2) is a potent negative regulator of apoptosis signal regulating kinase-1 (ASK1). Int J Biochem Cell Biol 2010; 42:1816-22. [PMID: 20674765 DOI: 10.1016/j.biocel.2010.07.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 07/09/2010] [Accepted: 07/21/2010] [Indexed: 11/28/2022]
Abstract
The function of protein phosphatases with EF-hand domains (PPEF) in mammals is not known. Large-scale expression profiling experiments suggest that PPEF expression may correlate with stress protective responses, cell survival, growth, proliferation, or neoplastic transformation. Apoptosis signal regulating kinase-1 (ASK1) is a MAP kinase kinase kinase implicated in cancer, cardiovascular and neurodegenerative diseases. ASK1 is activated by oxidative stress and induces pro-apoptotic or inflammatory signalling, largely via sustained activation of MAP kinases p38 and/or JNK. We identify human PPEF2 as a novel interacting partner and a negative regulator of ASK1. In COS-7 or HEK 293A cells treated with H(2)O(2), expression of PPEF2 abrogated sustained activation of p38 and one of the JNK p46 isoforms, and prevented ASK1-dependent caspase-3 cleavage and activation. PPEF2 efficiently suppressed H(2)O(2)-induced activation of ASK1. Overexpessed as well as endogenous ASK1 co-immunoprecipitated with PPEF2. PPEF2 was considerably more potent both as a suppressor of ASK1 activation and as its interacting partner as compared to protein phosphatase 5 (PP5), a well-known negative regulator of ASK1. PPEF2 was found to form complexes with endogenous Hsp70 and to a lesser extent Hsp90, which are also known interacting partners of PP5. These data identify, for the first time, a possible downstream signalling partner of a mammalian PPEF phosphatase, and suggest that, despite structural divergence, PPEF and PP5 phosphatases may share common interacting partners and functions.
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Affiliation(s)
- Mikhail A Kutuzov
- Department of Pharmacology (MC 868), University of Illinois at Chicago, Chicago, IL 60612, USA.
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39
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de Paulo Martins V, Okura M, Maric D, Engman DM, Vieira M, Docampo R, Moreno SNJ. Acylation-dependent export of Trypanosoma cruzi phosphoinositide-specific phospholipase C to the outer surface of amastigotes. J Biol Chem 2010; 285:30906-17. [PMID: 20647312 DOI: 10.1074/jbc.m110.142190] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphoinositide phospholipase C (PI-PLC) plays an essential role in cell signaling. A unique Trypanosoma cruzi PI-PLC (TcPI-PLC) is lipid-modified in its N terminus and localizes to the plasma membrane of amastigotes. Here, we show that TcPI-PLC is located onto the extracellular phase of the plasma membrane of amastigotes and that its N-terminal 20 amino acids are necessary and sufficient to target the fused GFP to the outer surface of the parasite. Mutagenesis of the predicted acylated residues confirmed that myristoylation of a glycine residue in the 2nd position and acyl modification of a cysteine in the 4th but not in the 8th or 15th position of the coding sequence are required for correct plasma membrane localization in T. cruzi epimastigotes or amastigotes. Interestingly, mutagenesis of the cysteine at the 8th position increased its flagellar localization. When expressed as fusion constructs with GFP, the N-terminal 6 and 10 amino acids fused to GFP are predominantly located in the cytosol and concentrated in a compartment that co-localizes with a Golgi complex marker. The N-terminal 20 amino acids of TcPI-PLC associate with lipid rafts when dually acylated. Taken together, these results indicate that N-terminal acyl modifications serve as a molecular addressing system for sending TcPI-PLC to the outer surface of the cell.
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Affiliation(s)
- Vicente de Paulo Martins
- Department of Cellular Biology, University of Georgia, Center for Tropical and Emerging Global Diseases, Athens, Georgia 30602, USA
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40
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Szöör B. Trypanosomatid protein phosphatases. Mol Biochem Parasitol 2010; 173:53-63. [PMID: 20594956 PMCID: PMC2994645 DOI: 10.1016/j.molbiopara.2010.05.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 05/21/2010] [Accepted: 05/24/2010] [Indexed: 01/09/2023]
Abstract
Protein phosphorylation is one of the most important post-translational modifications regulating various signaling processes in all known living organisms. In the cell, protein phosphatases and protein kinases play a dynamic antagonistic role, controlling the phosphorylation state of tyrosine (Tyr), serine (Ser) and threonine (Thr) side chains of proteins. The reversible phosphorylation modulates protein function, through initiating conformational changes, which influences protein complex formation, alteration of enzyme activity and changes in protein stability and subcellular localization. These molecular changes affect signaling cascades regulating the cell cycle, differentiation, cell-cell and cell-substrate interactions, cell motility, the immune response, ion-channel and transporter activities, gene transcription, mRNA translation, and basic metabolism. In addition to these processes, in unicellular parasites, like Trypanosoma brucei, Trypanosoma cruzi and Leishmania spp., additional signaling pathways have evolved to enable the survival of parasites in the changing environment of the vector and host organism. In recent years the genome of five trypanosomatid genomes have been sequenced and annotated allowing complete definition of the composition of the trypanosomatid phosphatomes. The very diverse environments involved in the different stages of the kinetoplastids' life cycle might have played a role to develop a set of trypanosomatid-specific phosphatases in addition to orthologues of many higher eukaryote protein phosphatases present in the kinetoplastid phosphatomes. In spite of their well-described phosphatomes, few trypanosomatid protein phosphatases have been characterized and studied in vivo. The aim of this review is to give an up to date scope of the research, which has been carried out on trypanosomatid protein phosphatases.
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Affiliation(s)
- Balázs Szöör
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, King's Building, West Mains Road, Edinburgh EH9 3JT, UK.
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41
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Frearson JA, Brand S, McElroy SP, Cleghorn LAT, Smid O, Stojanovski L, Price HP, Guther MLS, Torrie LS, Robinson DA, Hallyburton I, Mpamhanga CP, Brannigan JA, Wilkinson AJ, Hodgkinson M, Hui R, Qiu W, Raimi OG, van Aalten DMF, Brenk R, Gilbert IH, Read KD, Fairlamb AH, Ferguson MAJ, Smith DF, Wyatt PG. N-myristoyltransferase inhibitors as new leads to treat sleeping sickness. Nature 2010; 464:728-32. [PMID: 20360736 PMCID: PMC2917743 DOI: 10.1038/nature08893] [Citation(s) in RCA: 221] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 02/10/2010] [Indexed: 01/28/2023]
Abstract
African sleeping sickness or human African trypanosomiasis, caused by Trypanosoma brucei spp., is responsible for approximately 30,000 deaths each year. Available treatments for this disease are poor, with unacceptable efficacy and safety profiles, particularly in the late stage of the disease when the parasite has infected the central nervous system. Here we report the validation of a molecular target and the discovery of associated lead compounds with the potential to address this lack of suitable treatments. Inhibition of this target-T. brucei N-myristoyltransferase-leads to rapid killing of trypanosomes both in vitro and in vivo and cures trypanosomiasis in mice. These high-affinity inhibitors bind into the peptide substrate pocket of the enzyme and inhibit protein N-myristoylation in trypanosomes. The compounds identified have promising pharmaceutical properties and represent an opportunity to develop oral drugs to treat this devastating disease. Our studies validate T. brucei N-myristoyltransferase as a promising therapeutic target for human African trypanosomiasis.
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Affiliation(s)
- Julie A Frearson
- Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee DD1 5EH, UK
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42
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Brannigan JA, Smith BA, Yu Z, Brzozowski AM, Hodgkinson MR, Maroof A, Price HP, Meier F, Leatherbarrow RJ, Tate EW, Smith DF, Wilkinson AJ. N-myristoyltransferase from Leishmania donovani: structural and functional characterisation of a potential drug target for visceral leishmaniasis. J Mol Biol 2010; 396:985-99. [PMID: 20036251 PMCID: PMC2829124 DOI: 10.1016/j.jmb.2009.12.032] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Revised: 12/15/2009] [Accepted: 12/16/2009] [Indexed: 12/30/2022]
Abstract
N-Myristoyltransferase (NMT) catalyses the attachment of the 14-carbon saturated fatty acid, myristate, to the amino-terminal glycine residue of a subset of eukaryotic proteins that function in multiple cellular processes, including vesicular protein trafficking and signal transduction. In these pathways, N-myristoylation facilitates association of substrate proteins with membranes or the hydrophobic domains of other partner peptides. NMT function is essential for viability in all cell types tested to date, demonstrating that this enzyme has potential as a target for drug development. Here, we provide genetic evidence that NMT is likely to be essential for viability in insect stages of the pathogenic protozoan parasite, Leishmania donovani, causative agent of the tropical infectious disease, visceral leishmaniasis. The open reading frame of L. donovani NMT has been amplified and used to overproduce active recombinant enzyme in Escherichia coli, as demonstrated by gel mobility shift assays of ligand binding and peptide-myristoylation activity in scintillation proximity assays. The purified protein has been crystallized in complex with the non-hydrolysable substrate analogue S-(2-oxo)pentadecyl-CoA, and its structure was solved by molecular replacement at 1.4 A resolution. The structure has as its defining feature a 14-stranded twisted beta-sheet on which helices are packed so as to form an extended and curved substrate-binding groove running across two protein lobes. The fatty acyl-CoA is largely buried in the N-terminal lobe, its binding leading to the loosening of a flap, which in unliganded NMT structures, occludes the protein substrate binding site in the carboxy-terminal lobe. These studies validate L. donovani NMT as a potential target for development of new therapeutic agents against visceral leishmaniasis.
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Key Words
- arf, adp-ribosylation factor
- dig, digoxigenin
- hasp, hydrophilic acylated surface protein
- hyg, hygromycin
- neo, neomycin
- nhm, non-hydrolysable myristoyl-coa analogue
- nmt, n-myristoyltransferase
- orf, open reading frame
- pac, puromycin
- spa, scintillation proximity assay
- vl, visceral leishmaniasis
- canmt, hsnmt, ldnmt and scnmt, n-myristoyltransferase from candida albicans, homo sapiens, leishmania donovani and saccharomyces cerevisiae, respectively
- n-myristoyltransferase
- leishmania
- visceral leishmaniasis
- crystal structure
- drug target
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Affiliation(s)
- James A. Brannigan
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, UK
| | - Barbara A. Smith
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York YO10 5YW, UK
| | - Zhiyong Yu
- Department of Chemistry, Imperial College, London SW7 2AZ, UK
| | - Andrzej M. Brzozowski
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, UK
| | - Michael R. Hodgkinson
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York YO10 5YW, UK
| | - Asher Maroof
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York YO10 5YW, UK
| | - Helen P. Price
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York YO10 5YW, UK
| | - Franziska Meier
- Department of Chemistry, Imperial College, London SW7 2AZ, UK
| | | | - Edward W. Tate
- Department of Chemistry, Imperial College, London SW7 2AZ, UK
| | - Deborah F. Smith
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York YO10 5YW, UK
| | - Anthony J. Wilkinson
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, UK
- Corresponding author.
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Tull D, Naderer T, Spurck T, Mertens HDT, Heng J, McFadden GI, Gooley PR, McConville MJ. Membrane protein SMP-1 is required for normal flagellum function in Leishmania. J Cell Sci 2010; 123:544-54. [PMID: 20086045 DOI: 10.1242/jcs.059097] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Eukaryotic flagella and cilia are surrounded by a membrane that is continuous with, but distinct from, the rest of the plasma membrane. In Leishmania parasites, the inner leaflet of the flagellar membrane is coated with the acylated membrane protein, SMP-1. Here, we provide evidence that SMP-1 stabilizes the flagellar membrane and is required for flagella elongation and function. The expression and flagella targeting of SMP-1 is tightly associated with flagella elongation during amastigote to promastigote differentiation. Deletion of the genes encoding SMP-1 and the flagellar pocket protein SMP-2, led to the production of short flagella and defects in motility. Alterations in the physical properties of the smp-1/smp-2(-/-) flagellar membrane were suggested by: (1) the accumulation of membrane vesicles in the flagellar matrix, and (2) further retraction of flagella following partial inhibition of sterol and sphingolipid biosynthesis. The flagella phenotype of the smp-1/smp-2(-/-) null mutant was reversed by re-expression of SMP-1, but not SMP-2. SMP-1 contains a jelly-roll beta-sheet structure that is probably conserved in all SMP proteins, and forms stable homo-oligomers in vivo. We propose that the SMP-1 coat generates and/or stabilizes sterol- and sphingolipid-rich domains in the flagellar membrane.
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Affiliation(s)
- Dedreia Tull
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
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44
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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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45
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Price HP, Güther MLS, Ferguson MAJ, Smith DF. Myristoyl-CoA:protein N-myristoyltransferase depletion in trypanosomes causes avirulence and endocytic defects. Mol Biochem Parasitol 2009; 169:55-8. [PMID: 19782106 PMCID: PMC2789243 DOI: 10.1016/j.molbiopara.2009.09.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 09/14/2009] [Accepted: 09/17/2009] [Indexed: 12/17/2022]
Abstract
The enzyme myristoyl-CoA:protein N-myristoyltransferase (NMT) catalyses the co-translational covalent attachment of the fatty acid myristate to the N-terminus of target proteins. NMT is known to be essential for viability in Trypanosoma brucei and Leishmania major. Here we describe phenotypic analysis of T. brucei bloodstream form cells following knockdown of NMT expression by tetracycline-inducible RNA interference. Cell death occurs from 72 h post-induction, with approximately 50% of cells displaying a defect in endocytic uptake by this time. The majority of these induced cells do not have an enlarged flagellar pocket typical of a block in endocytosis but vesicle accumulation around the flagellar pocket indicates a defect in vesicular progression following endocytic fusion. Induced parasites have a wild-type or slightly enlarged Golgi apparatus, unlike the phenotype of cells with reduced expression of a major N-myristoylated protein, ARL1. Critically we show that following NMT knockdown, T. brucei bloodstream form cells are unable to establish an infection in a mouse model, therefore providing further validation of this enzyme as a target for drug development.
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Affiliation(s)
- Helen P Price
- Centre for Immunology and Infection, Department of Biology, University of York, UK.
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46
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Liu W, Apagyi K, McLeavy L, Ersfeld K. Expression and cellular localisation of calpain-like proteins in Trypanosoma brucei. Mol Biochem Parasitol 2009; 169:20-6. [PMID: 19766148 DOI: 10.1016/j.molbiopara.2009.09.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 09/07/2009] [Accepted: 09/08/2009] [Indexed: 01/01/2023]
Abstract
Calpains are a ubiquitous family of calcium-dependent cysteine proteases involved in a wide range of cell regulatory and differentiation processes. In many protozoan organisms, atypical calpains have been discovered that lack the characteristic calcium-binding penta-EF-hand motif of typical vertebrate calpains and most of these novel calpain-like proteins are non-enzymatic homologues of typical calpains. The gene family is particularly expanded in ciliates and kinetoplastids, comprising 25 members in the parasite Trypanosoma brucei. Unique to kinetoplastids, some calpain-like proteins contain N-terminal dual myristoylation/palmitoylation signals, a protein modification involved in protein-membrane associations. We analyzed the expression of calpain-like proteins in the insect (procyclic) and bloodstream-stage of T. brucei using quantitative real time PCR and identified the differential expression of some of the calpain genes. We also present a comprehensive analysis of the subcellular localisation of selected members of this protein family in trypanosomes. Here, of particular interest is the role of protein acylation for targeting to the flagellum. We show that, although acylation is important for flagellar targeting, additional signals are required to specify the precise subcellular localisation.
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Affiliation(s)
- Wen Liu
- Department of Biological Sciences, University of Hull, UK
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47
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Depledge DP, Evans KJ, Ivens AC, Aziz N, Maroof A, Kaye PM, Smith DF. Comparative expression profiling of Leishmania: modulation in gene expression between species and in different host genetic backgrounds. PLoS Negl Trop Dis 2009; 3:e476. [PMID: 19582145 PMCID: PMC2701600 DOI: 10.1371/journal.pntd.0000476] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 06/02/2009] [Indexed: 12/03/2022] Open
Abstract
Background Genome sequencing of Leishmania species that give rise to a range of disease phenotypes in the host has revealed highly conserved gene content and synteny across the genus. Only a small number of genes are differentially distributed between the three species sequenced to date, L. major, L. infantum and L. braziliensis. It is not yet known how many of these genes are expressed in the disease-promoting intracellular amastigotes of these species or whether genes conserved between the species are differentially expressed in the host. Methods/Principal Findings We have used customised oligonucleotide microarrays to confirm that all of the differentially distributed genes identified by genome comparisons are expressed in intracellular amastigotes, with only a few of these subject to regulation at the RNA level. In the first large-scale study of gene expression in L. braziliensis, we show that only ∼9% of the genes analysed are regulated in their RNA expression during the L. braziliensis life cycle, a figure consistent with that observed in other Leishmania species. Comparing amastigote gene expression profiles between species confirms the proposal that Leishmania transcriptomes undergo little regulation but also identifies conserved genes that are regulated differently between species in the host. We have also investigated whether host immune competence influences parasite gene expression, by comparing RNA expression profiles in L. major amastigotes derived from either wild-type (BALB/c) or immunologically compromised (Rag2−/− γc−/−) mice. While parasite dissemination from the site of infection is enhanced in the Rag2−/− γc−/− genetic background, parasite RNA expression profiles are unperturbed. Conclusion/Significance These findings support the hypothesis that Leishmania amastigotes are pre-adapted for intracellular survival and undergo little dynamic modulation of gene expression at the RNA level. Species-specific parasite factors contributing to virulence and pathogenicity in the host may be limited to the products of a small number of differentially distributed genes or the differential regulation of conserved genes, either of which are subject to translational and/or post-translational controls. The single-celled parasite Leishmania, transmitted by sand flies in more than 88 tropical and sub-tropical countries globally, infects man and other mammals, causing a spectrum of diseases called the leishmaniases. Over 12 million people are currently infected worldwide with 2 million new cases reported each year. The type of leishmaniasis that develops in the mammalian host is dependent on the species of infecting parasite and the immune response to infection (that can be influenced by host genetic variation). Our research is focused on identifying parasite factors that contribute to pathogenicity in the host and understanding how these might differ between parasite species that give rise to the different clinical forms of leishmaniasis. Molecules of this type might lead to new therapeutic tools in the longer term. In this paper, we report a comparative analysis of gene expression profiles in three Leishmania species that give rise to different types of disease, focusing on the intracellular stages that reside in mammalian macrophages. Our results show that there are only a small number of differences between these parasite species, with host genetics playing only a minor role in influencing the parasites' response to their intracellular habitat. These small changes may be significant, however, in determining the clinical outcome of infection.
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Affiliation(s)
- Daniel P. Depledge
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York, United Kingdom
| | - Krystal J. Evans
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York, United Kingdom
| | | | - Naveed Aziz
- Technology Facility, Department of Biology, University of York, York, United Kingdom
| | - Asher Maroof
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York, United Kingdom
| | - Paul M. Kaye
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York, United Kingdom
| | - Deborah F. Smith
- Centre for Immunology and Infection, Department of Biology/Hull York Medical School, University of York, York, United Kingdom
- * E-mail:
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Emmer BT, Souther C, Toriello KM, Olson CL, Epting CL, Engman DM. Identification of a palmitoyl acyltransferase required for protein sorting to the flagellar membrane. J Cell Sci 2009; 122:867-74. [PMID: 19240115 DOI: 10.1242/jcs.041764] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Protein palmitoylation has diverse effects in regulating protein membrane affinity, localization, binding partner interactions, turnover and function. Here, we show that palmitoylation also contributes to the sorting of proteins to the eukaryotic flagellum. African trypanosomes are protozoan pathogens that express a family of unique Ca(2+)-binding proteins, the calflagins, which undergo N-terminal myristoylation and palmitoylation. The localization of calflagins depends on their acylation status. Myristoylation alone is sufficient for membrane association, but, in the absence of palmitoylation, the calflagins localize to the pellicular (cell body) membrane. Palmitoylation, which is mediated by a specific palmitoyl acyltransferase, is then required for subsequent trafficking of calflagin to the flagellar membrane. Coincident with the redistribution of calflagin from the pellicular to the flagellar membrane is their association with lipid rafts, which are highly enriched in the flagellar membrane. Screening of candidate palmitoyl acyltranferases identified a single enzyme, TbPAT7, that is necessary for calflagin palmitoylation and flagellar membrane targeting. Our results implicate protein palmitoylation in flagellar trafficking, and demonstrate the conservation and specificity of palmitoyl acyltransferase activity by DHHC-CRD proteins across kingdoms.
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Affiliation(s)
- Brian T Emmer
- Departments of Pathology and Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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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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50
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Bowyer PW, Tate EW, Leatherbarrow RJ, Holder AA, Smith DF, Brown KA. N-myristoyltransferase: a prospective drug target for protozoan parasites. ChemMedChem 2008; 3:402-8. [PMID: 18324715 DOI: 10.1002/cmdc.200700301] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Paul W Bowyer
- Division of Cell and Molecular Biology, Centre for Molecular Microbiology and Infection, Imperial College London, London SW7 2AZ, UK
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