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Jain S, Sahu U, Kumar A, Khare P. Metabolic Pathways of Leishmania Parasite: Source of Pertinent Drug Targets and Potent Drug Candidates. Pharmaceutics 2022; 14:pharmaceutics14081590. [PMID: 36015216 PMCID: PMC9416627 DOI: 10.3390/pharmaceutics14081590] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 02/04/2023] Open
Abstract
Leishmaniasis is a tropical disease caused by a protozoan parasite Leishmania that is transmitted via infected female sandflies. At present, leishmaniasis treatment mainly counts on chemotherapy. The currently available drugs against leishmaniasis are costly, toxic, with multiple side effects, and limitations in the administration route. The rapid emergence of drug resistance has severely reduced the potency of anti-leishmanial drugs. As a result, there is a pressing need for the development of novel anti-leishmanial drugs with high potency, low cost, acceptable toxicity, and good pharmacokinetics features. Due to the availability of preclinical data, drug repurposing is a valuable approach for speeding up the development of effective anti-leishmanial through pointing to new drug targets in less time, having low costs and risk. Metabolic pathways of this parasite play a crucial role in the growth and proliferation of Leishmania species during the various stages of their life cycle. Based on available genomics/proteomics information, known pathways-based (sterol biosynthetic pathway, purine salvage pathway, glycolysis, GPI biosynthesis, hypusine, polyamine biosynthesis) Leishmania-specific proteins could be targeted with known drugs that were used in other diseases, resulting in finding new promising anti-leishmanial therapeutics. The present review discusses various metabolic pathways of the Leishmania parasite and some drug candidates targeting these pathways effectively that could be potent drugs against leishmaniasis in the future.
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Affiliation(s)
- Surbhi Jain
- Department of Microbiology, All India Institute of Medical Sciences, Bhopal 462026, Madhya Pradesh, India; (S.J.); (U.S.)
| | - Utkarsha Sahu
- Department of Microbiology, All India Institute of Medical Sciences, Bhopal 462026, Madhya Pradesh, India; (S.J.); (U.S.)
- Division of Synthetic Biology, Absolute Foods, Plot 68, Sector 44, Gurugram 122003, Haryana, India
| | - Awanish Kumar
- Department of Biotechnology, National Institute of Technology, Raipur 492010, Chhattisgarh, India
- Correspondence: or (A.K.); (P.K.)
| | - Prashant Khare
- Department of Microbiology, All India Institute of Medical Sciences, Bhopal 462026, Madhya Pradesh, India; (S.J.); (U.S.)
- Division of Synthetic Biology, Absolute Foods, Plot 68, Sector 44, Gurugram 122003, Haryana, India
- Correspondence: or (A.K.); (P.K.)
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2
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Abstract
Outbreaks of trichinellosis caused by Trichinella papuae have been reported in South-East Asia. Mebendazole and thiabendazole are the treatments of choice for trichinellosis; however, both drugs result in significant side effects and are less effective for muscle-stage larvae (L1). An alternative therapeutic agent is needed to improve treatment. Information on lipid composition and metabolic pathways may bridge gaps in our knowledge and lead to new antiparasitics. The T. papuae L1 lipidome was analysed using a mass spectrometry-based approach, and 403 lipid components were identified. Eight lipid classes were found and glycerophospholipids were dominant, corresponding to 63% of total lipids, of which the glycerolipid DG (20:1[11Z]/22:4[7Z,10Z,13Z,16Z]/0:0) (iso2) was the most abundant. Overall, 57% of T. papuae lipids were absent in humans; therefore, lipid metabolism may be dissimilar in the two species. Proteins involved T. papuae lipid metabolism were explored using bioinformatics. We found that 4-hydroxybutyrate coenzyme A transferase, uncharacterized protein (A0A0V1MCB5) and ML-domain-containing protein are not present in humans. T. papuae glycerophospholipid metabolic and phosphatidylinositol dephosphorylation processes contain several proteins that are dissimilar to those in humans. These findings provide insights into T. papuae lipid composition and metabolism, which may facilitate the development of novel trichinellosis treatments.
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Mosquillo MF, Smircich P, Ciganda M, Lima A, Gambino D, Garat B, Pérez-Díaz L. Comparative high-throughput analysis of the Trypanosoma cruzi response to organometallic compounds. Metallomics 2020; 12:813-828. [DOI: 10.1039/d0mt00030b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
An in-depth, comparative look at the effects of two structurally related organometallic Pd and Pt compounds on the global gene expression pattern of T. cruzi epimastigotes. This parasite is the causative agent of Chagas disease.
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Affiliation(s)
- M. Florencia Mosquillo
- Laboratorio de Interacciones Moleculares
- Facultad de Ciencias
- Universidad de la República
- Montevideo
- Uruguay
| | - Pablo Smircich
- Laboratorio de Interacciones Moleculares
- Facultad de Ciencias
- Universidad de la República
- Montevideo
- Uruguay
| | | | - Analía Lima
- Instituto de Investigaciones Biológicas Clemente Estable
- Montevideo
- Uruguay
- Unidad de Bioquímica y Proteómica Analíticas
- Institut Pasteur de Montevideo
| | - Dinorah Gambino
- Área Química Inorgánica
- Facultad de Química
- Universidad de la República
- Montevideo
- Uruguay
| | - Beatriz Garat
- Laboratorio de Interacciones Moleculares
- Facultad de Ciencias
- Universidad de la República
- Montevideo
- Uruguay
| | - Leticia Pérez-Díaz
- Laboratorio de Interacciones Moleculares
- Facultad de Ciencias
- Universidad de la República
- Montevideo
- Uruguay
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4
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Decker Franco C, Wieser SN, Soria M, de Alba P, Florin-Christensen M, Schnittger L. In silico identification of immunotherapeutic and diagnostic targets in the glycosylphosphatidylinositol metabolism of the coccidian Sarcocystis aucheniae. Transbound Emerg Dis 2019; 67 Suppl 2:165-174. [PMID: 31880101 DOI: 10.1111/tbed.13438] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Meat of the South American camelids (SACs) llama and alpaca is an important source of animal protein and income for rural families in the Andes, and a product with significant growth potential for local and international markets. However, infestation with macroscopic cysts of the coccidian protozoon Sarcocystis aucheniae, a parasitosis known as SAC sarcocystosis, significantly hampers its commercialization. There are no validated methods to diagnose the presence of S. aucheniae cysts other than carcass examination. Moreover, there are no available drugs or vaccines to cure or prevent SAC sarcocystosis. Identification of relevant molecules that act at the host-pathogen interface can significantly contribute to the control of this disease. It has been shown for other pathogenic protozoa that glycosylphosphatidylinositol (GPI) is a critical molecule implicated in parasite survival and pathogenicity. This study focused on the identification of the enzymes that participate in the S. aucheniae GPI biosynthetic pathway and the repertoire of the parasite GPI-anchored proteins (GPI-APs). To this aim, RNA was extracted from parasite cysts and the transcriptome was sequenced and translated into amino acid sequences. The generated database was mined using sequences of well-characterized GPI biosynthetic enzymes of Saccharomyces cerevisiae and Toxoplasma gondii. Eleven enzymes predicted to participate in the S. aucheniae GPI biosynthetic pathway were identified. On the other hand, the database was searched for proteins carrying an N-terminal signal peptide and a single C-terminal transmembrane region containing a GPI anchor signal. Twenty-four GPI-anchored peptides were identified, of which nine are likely S. aucheniae-specific, and 15 are homologous to membrane proteins of other coccidians. Among the latter, 13 belong to the SRS domain superfamily, an extensive group of coccidian GPI-anchored proteins that mediate parasite interaction with their host. Phylogenetic analysis showed a great degree of intra- and inter-specific divergence among SRS family proteins. In vitro and in vivo experiments are needed to validate S. aucheniae GPI biosynthetic enzymes and GPI-APs as drug targets and/or as vaccine or diagnostic antigens.
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Affiliation(s)
- Cecilia Decker Franco
- Instituto de Patobiología Veterinaria, CICVyA, INTA-Castelar, Hurlingham, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Sarah N Wieser
- Instituto de Patobiología Veterinaria, CICVyA, INTA-Castelar, Hurlingham, Buenos Aires, Argentina
| | - Marcelo Soria
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.,Microbiología Agrícola, Facultad de Agronomía, Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Paloma de Alba
- Instituto de Patobiología Veterinaria, CICVyA, INTA-Castelar, Hurlingham, Buenos Aires, Argentina
| | - Mónica Florin-Christensen
- Instituto de Patobiología Veterinaria, CICVyA, INTA-Castelar, Hurlingham, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Leonhard Schnittger
- Instituto de Patobiología Veterinaria, CICVyA, INTA-Castelar, Hurlingham, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
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5
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Morotti ALM, Martins-Teixeira MB, Carvalho I. Protozoan Parasites Glycosylphosphatidylinositol Anchors: Structures, Functions and Trends for Drug Discovery. Curr Med Chem 2019; 26:4301-4322. [PMID: 28748758 DOI: 10.2174/0929867324666170727110801] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/12/2017] [Accepted: 07/12/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND Glycosylphosphatidylinositol (GPI) anchors are molecules located on cell membranes of all eukaryotic organisms. Proteins, enzymes, and other macromolecules which are anchored by GPIs are essential elements for interaction between cells, and are widely used by protozoan parasites when compared to higher eukaryotes. METHODS More than one hundred references were collected to obtain broad information about mammalian and protozoan parasites' GPI structures, biosynthetic pathways, functions and attempts to use these molecules as drug targets against parasitic diseases. Differences between GPI among species were compared and highlighted. Strategies for drug discovery and development against protozoan GPI anchors were discussed based on what has been reported on literature. RESULTS There are many evidences that GPI anchors are crucial for parasite's survival and interaction with hosts' cells. Despite all GPI anchors contain a conserved glycan core, they present variations regarding structural features and biosynthetic pathways between organisms, which could offer adequate selectivity to validate GPI anchors as drug targets. Discussion was developed with focus on the following parasites: Trypanosoma brucei, Trypanosoma cruzi, Leishmania, Plasmodium falciparum and Toxoplasma gondii, causative agents of tropical neglected diseases. CONCLUSION This review debates the main variances between parasitic and mammalian GPI anchor biosynthesis and structures, as well as clues for strategic development for new anti-parasitic therapies based on GPI anchors.
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Affiliation(s)
- Ana Luísa Malaco Morotti
- School of Pharmaceutical Sciences of Ribeirao Preto - University of Sao Paulo, Sao Paulo, Brazil
| | | | - Ivone Carvalho
- School of Pharmaceutical Sciences of Ribeirao Preto - University of Sao Paulo, Sao Paulo, Brazil
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6
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Kennedy K, Crisafulli EM, Ralph SA. Delayed Death by Plastid Inhibition in Apicomplexan Parasites. Trends Parasitol 2019; 35:747-759. [PMID: 31427248 DOI: 10.1016/j.pt.2019.07.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/25/2019] [Accepted: 07/26/2019] [Indexed: 01/11/2023]
Abstract
The discovery of a plastid in apicomplexan parasites was hoped to be a watershed moment in the treatment of parasitic diseases as it revealed drug targets that are implicitly divergent from host molecular processes. Indeed, this organelle, known as the apicoplast, has since been a productive therapeutic target for pharmaceutical interventions against infections by Plasmodium, Toxoplasma, Babesia, and Theileria. However, some inhibitors of the apicoplast are restricted in their treatment utility because of their slow-kill kinetics, and this characteristic is called the delayed death effect. Here we review the recent genetic and pharmacological experiments that interrogate the causes of delayed death and explore the foundation of this phenomenon in Plasmodium and Toxoplasma parasites.
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Affiliation(s)
- Kit Kennedy
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Emily M Crisafulli
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Stuart A Ralph
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, 3010, Australia.
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7
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Starkl Renar K, Iskra J, Križaj I. Understanding malarial toxins. Toxicon 2016; 119:319-29. [PMID: 27353131 DOI: 10.1016/j.toxicon.2016.06.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 05/26/2016] [Accepted: 06/24/2016] [Indexed: 10/21/2022]
Abstract
Recognized since antiquity, malaria is one of the most infamous and widespread infectious diseases in humans and, although the death rate during the last century has been diminishing, it still accounts for more than a half million deaths annually. It is caused by the Plasmodium parasite and typical symptoms include fever, shivering, headache, diaphoresis and nausea, all resulting from an excessive inflammatory response induced by malarial toxins released into the victim's bloodstream. These toxins are hemozoin and glycosylphosphatidylinositols. The former is the final product of the parasite's detoxification of haeme, a by-product of haemoglobin catabolism, while the latter anchor proteins to the Plasmodium cell surface or occur as free molecules. Currently, only two groups of antimalarial toxin drugs exist on the market, quinolines and artemisinins. As we describe, they both target biosynthesis of hemozoin. Other substances, currently in various phases of clinical trials, are directed towards biosynthesis of glycosylphosphatidylinositol, formation of hemozoin, or attenuation of the inflammatory response of the patient. Among the innovative approaches to alleviating the effects of malarial toxins, is the development of antimalarial toxin vaccines. In this review the most important lessons learned from the use of treatments directed against the action of malarial toxins in antimalarial therapy are emphasized and the most relevant and promising directions for future research in obtaining novel antimalarial agents acting on malarial toxins are discussed.
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Affiliation(s)
- Katarina Starkl Renar
- Laboratory of Organic and Bioorganic Chemistry, Department of Physical and Organic Chemistry, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Jamova 39, 1000 Ljubljana, Slovenia.
| | - Jernej Iskra
- Laboratory of Organic and Bioorganic Chemistry, Department of Physical and Organic Chemistry, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Igor Križaj
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia; Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
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8
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Abstract
Apicomplexan parasites include some of the most prevalent and deadly human pathogens. Novel antiparasitic drugs are urgently needed. Synthesis and metabolism of isoprenoids may present multiple targets for therapeutic intervention. The apicoplast-localized methylerythritol phosphate (MEP) pathway for isoprenoid precursor biosynthesis is distinct from the mevalonate (MVA) pathway used by the mammalian host, and this pathway is apparently essential in most Apicomplexa. In this review, we discuss the current field of research on production and metabolic fates of isoprenoids in apicomplexan parasites, including the acquisition of host isoprenoid precursors and downstream products. We describe recent work identifying the first MEP pathway regulator in apicomplexan parasites, and introduce several promising areas for ongoing research into this well-validated antiparasitic target.
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Affiliation(s)
- Leah Imlay
- Department of Molecular Microbiology Washington University School of Medicine St. Louis, MO 63110 USA
| | - Audrey R Odom
- Department of Pediatrics Washington University School of Medicine St. Louis, MO 63110 USA & Department of Molecular Microbiology Washington University School of Medicine St. Louis, MO 63110 USA
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9
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Guggisberg AM, Amthor RE, Odom AR. Isoprenoid biosynthesis in Plasmodium falciparum. EUKARYOTIC CELL 2014; 13:1348-59. [PMID: 25217461 PMCID: PMC4248697 DOI: 10.1128/ec.00160-14] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Malaria kills nearly 1 million people each year, and the protozoan parasite Plasmodium falciparum has become increasingly resistant to current therapies. Isoprenoid synthesis via the methylerythritol phosphate (MEP) pathway represents an attractive target for the development of new antimalarials. The phosphonic acid antibiotic fosmidomycin is a specific inhibitor of isoprenoid synthesis and has been a helpful tool to outline the essential functions of isoprenoid biosynthesis in P. falciparum. Isoprenoids are a large, diverse class of hydrocarbons that function in a variety of essential cellular processes in eukaryotes. In P. falciparum, isoprenoids are used for tRNA isopentenylation and protein prenylation, as well as the synthesis of vitamin E, carotenoids, ubiquinone, and dolichols. Recently, isoprenoid synthesis in P. falciparum has been shown to be regulated by a sugar phosphatase. We outline what is known about isoprenoid function and the regulation of isoprenoid synthesis in P. falciparum, in order to identify valuable directions for future research.
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Affiliation(s)
- Ann M Guggisberg
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Rachel E Amthor
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Audrey R Odom
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
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10
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Liebens V, Defraine V, Van der Leyden A, De Groote VN, Fierro C, Beullens S, Verstraeten N, Kint C, Jans A, Frangipani E, Visca P, Marchal K, Versées W, Fauvart M, Michiels J. A putative de-N-acetylase of the PIG-L superfamily affects fluoroquinolone tolerance in Pseudomonas aeruginosa. Pathog Dis 2014; 71:39-54. [PMID: 24692291 DOI: 10.1111/2049-632x.12174] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 03/13/2014] [Accepted: 03/21/2014] [Indexed: 11/29/2022] Open
Abstract
A major cause of treatment failure of infections caused by Pseudomonas aeruginosa is the presence of antibiotic-insensitive persister cells. The mechanism of persister formation in P. aeruginosa is largely unknown, and so far, only few genetic determinants have been linked to P. aeruginosa persistence. Based on a previous high-throughput screening, we here present dnpA (de-N-acetylase involved in persistence; gene locus PA14_66140/PA5002) as a new gene involved in noninherited fluoroquinolone tolerance in P. aeruginosa. Fluoroquinolone tolerance of a dnpA mutant is strongly reduced both in planktonic culture and in a biofilm model, whereas overexpression of dnpA in the wild-type strain increases the persister fraction. In addition, the susceptibility of the dnpA mutant to different classes of antibiotics is not affected. dnpA is part of the conserved LPS core oligosaccharide biosynthesis gene cluster. Based on primary sequence analysis, we predict that DnpA is a de-N-acetylase, acting on an unidentified substrate. Site-directed mutagenesis suggests that this enzymatic activity is essential for DnpA-mediated persistence. A transcriptome analysis indicates that DnpA primarily affects the expression of genes involved in surface-associated processes. We discuss the implications of these findings for future antipersister therapies targeted at chronic P. aeruginosa infections.
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Affiliation(s)
- Veerle Liebens
- Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
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11
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Targeting lipid biosynthesis and salvage in apicomplexan parasites for improved chemotherapies. Nat Rev Microbiol 2013; 11:823-35. [DOI: 10.1038/nrmicro3139] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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12
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Identification and functional analysis of Trypanosoma cruzi genes that encode proteins of the glycosylphosphatidylinositol biosynthetic pathway. PLoS Negl Trop Dis 2013; 7:e2369. [PMID: 23951384 PMCID: PMC3738449 DOI: 10.1371/journal.pntd.0002369] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/01/2013] [Indexed: 12/03/2022] Open
Abstract
Background Trypanosoma cruzi is a protist parasite that causes Chagas disease. Several proteins that are essential for parasite virulence and involved in host immune responses are anchored to the membrane through glycosylphosphatidylinositol (GPI) molecules. In addition, T. cruzi GPI anchors have immunostimulatory activities, including the ability to stimulate the synthesis of cytokines by innate immune cells. Therefore, T. cruzi genes related to GPI anchor biosynthesis constitute potential new targets for the development of better therapies against Chagas disease. Methodology/Principal Findings In silico analysis of the T. cruzi genome resulted in the identification of 18 genes encoding proteins of the GPI biosynthetic pathway as well as the inositolphosphorylceramide (IPC) synthase gene. Expression of GFP fusions of some of these proteins in T. cruzi epimastigotes showed that they localize in the endoplasmic reticulum (ER). Expression analyses of two genes indicated that they are constitutively expressed in all stages of the parasite life cycle. T. cruzi genes TcDPM1, TcGPI10 and TcGPI12 complement conditional yeast mutants in GPI biosynthesis. Attempts to generate T. cruzi knockouts for three genes were unsuccessful, suggesting that GPI may be an essential component of the parasite. Regarding TcGPI8, which encodes the catalytic subunit of the transamidase complex, although we were able to generate single allele knockout mutants, attempts to disrupt both alleles failed, resulting instead in parasites that have undergone genomic recombination and maintained at least one active copy of the gene. Conclusions/Significance Analyses of T. cruzi sequences encoding components of the GPI biosynthetic pathway indicated that they are essential genes involved in key aspects of host-parasite interactions. Complementation assays of yeast mutants with these T. cruzi genes resulted in yeast cell lines that can now be employed in high throughput screenings of drugs against this parasite. Chagas disease, considered one of the most neglected tropical diseases, is caused by the blood-borne parasite Trypanosoma cruzi and currently affects about 8 million people in Latin America. T. cruzi can be transmitted by insect vectors, blood transfusion, organ transplantation and mother-to-baby as well as through ingestion of contaminated food. Although T. cruzi causes life-long infections that can result in serious damage to the heart, the two drugs currently available to treat Chagas disease, benznidazole and nifurtimox, which have been used for more than 40 years, have proven efficacy only during the acute phase of the disease. Thus, there is an urgent need to develop new drugs that are more targeted, less toxic, and more effective against this parasite. Here we described the characterization of T. cruzi genes involved in the biosynthesis of GPI anchors, a molecule responsible for holding different types of glycoproteins on the parasite membrane. Since GPI anchored proteins are essential molecules T. cruzi uses during infection, besides helping understand how this parasite interacts with its host, this work may contribute to the development of better therapies against Chagas disease.
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Swarts BM. Recent Advances in the Chemical Synthesis of Glycosylphosphatidylinositols (GPIs): Expanding Synthetic Versatility for Investigating GPI Biology. J Carbohydr Chem 2013. [DOI: 10.1080/07328303.2013.831435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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14
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Ashraf M, Sreejith P, Yadav U, Komath SS. Catalysis by N-acetyl-D-glucosaminylphosphatidylinositol de-N-acetylase (PIG-L) from Entamoeba histolytica: new roles for conserved residues. J Biol Chem 2013; 288:7590-7595. [PMID: 23341455 DOI: 10.1074/jbc.m112.427245] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We showed previously that Entamoeba histolytica PIG-L exhibits a novel metal-independent albeit metal-stimulated activity. Using mutational and biochemical analysis, here we identify Asp-46 and His-140 of the enzyme as being important for catalysis. We show that these mutations neither affect the global conformational of the enzyme nor alter its metal binding affinity. The defect in catalysis, due to the mutations, is specifically due to an effect on V(max) and not due to altered substrate affinity (or K(m)). We propose a general acid-base pair mechanism to explain our results.
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Affiliation(s)
- Mohammad Ashraf
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | | | - Usha Yadav
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sneha Sudha Komath
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
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15
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Protein palmitoylation and pathogenesis in apicomplexan parasites. J Biomed Biotechnol 2012; 2012:483969. [PMID: 23093847 PMCID: PMC3470895 DOI: 10.1155/2012/483969] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 07/18/2012] [Accepted: 07/24/2012] [Indexed: 01/02/2023] Open
Abstract
Apicomplexan parasites comprise a broad variety of protozoan parasites, including Toxoplasma gondii, Plasmodium, Eimeria, and Cryptosporidium species. Being intracellular parasites, the success in establishing pathogenesis relies in their ability to infect a host-cell and replicate within it. Protein palmitoylation is known to affect many aspects of cell biology. Furthermore, palmitoylation has recently been shown to affect important processes in T. gondii such as replication, invasion, and gliding. Thus, this paper focuses on the importance of protein palmitoylation in the pathogenesis of apicomplexan parasites.
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16
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E1210, a new broad-spectrum antifungal, suppresses Candida albicans hyphal growth through inhibition of glycosylphosphatidylinositol biosynthesis. Antimicrob Agents Chemother 2011; 56:960-71. [PMID: 22143530 DOI: 10.1128/aac.00731-11] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Continued research toward the development of new antifungals that act via inhibition of glycosylphosphatidylinositol (GPI) biosynthesis led to the design of E1210. In this study, we assessed the selectivity of the inhibitory activity of E1210 against Candida albicans GWT1 (Orf19.6884) protein, Aspergillus fumigatus GWT1 (AFUA_1G14870) protein, and human PIG-W protein, which can catalyze the inositol acylation of GPI early in the GPI biosynthesis pathway, and then we assessed the effects of E1210 on key C. albicans virulence factors. E1210 inhibited the inositol acylation activity of C. albicans Gwt1p and A. fumigatus Gwt1p with 50% inhibitory concentrations (IC(50)s) of 0.3 to 0.6 μM but had no inhibitory activity against human Pig-Wp even at concentrations as high as 100 μM. To confirm the inhibition of fungal GPI biosynthesis, expression of ALS1 protein, a GPI-anchored protein, on the surfaces of C. albicans cells treated with E1210 was studied and shown to be significantly lower than that on untreated cells. However, the ALS1 protein levels in the crude extract and the RHO1 protein levels on the cell surface were found to be almost the same. Furthermore, E1210 inhibited germ tube formation, adherence to polystyrene surfaces, and biofilm formation of C. albicans at concentrations above its MIC. These results suggested that E1210 selectively inhibited inositol acylation of fungus-specific GPI which would be catalyzed by Gwt1p, leading to the inhibition of GPI-anchored protein maturation, and also that E1210 suppressed the expression of some important virulence factors of C. albicans, through its GPI biosynthesis inhibition.
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Leishmania-induced repression of selected non-coding RNA genes containing B-box element at their promoters in alternatively polarized M2 macrophages. Mol Cell Biochem 2010; 350:47-57. [PMID: 21165676 DOI: 10.1007/s11010-010-0681-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 12/02/2010] [Indexed: 12/14/2022]
Abstract
Leishmania is a group of parasitic protozoa that infect blood and tissue phagocytes including macrophages. We hypothesize that Leishmania is capable of establishing infection inside the macrophages because (a) they infect a subpopulation of macrophages; and (b) they "renovate" the macrophages before the establishment of infection. We found that only alternatively activated polarized M2 macrophages support Leishmania growth. Exposure of M2 macrophages to Leishmania promastigotes represses several selected RNA polymerase III (PolIII)-transcribed non-coding RNA (ncRNA) genes including those of 7SL RNA, vault RNA, and B2 RNA which have B-box element at their promoters. The B-box-binding transcription factor TFIIIC110 is down-regulated in Leishmania-exposed macrophages. Both the surface protease gp63 and the surface glycolipid LPG are required for the down-regulation of the ncRNAs in the M2 macrophages. We conclude that Leishmania surface gp63 collaborates with LPG to down-regulate TFIIIC110 in M2 macrophages to repress B-box containing ncRNA gene promoters.
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Macedo CSD, Schwarz RT, Todeschini AR, Previato JO, Mendonça-Previato L. Overlooked post-translational modifications of proteins in Plasmodium falciparum: N- and O-glycosylation - A Review. Mem Inst Oswaldo Cruz 2010; 105:949-56. [DOI: 10.1590/s0074-02762010000800001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2010] [Accepted: 11/16/2010] [Indexed: 11/22/2022] Open
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Azzouz N, Kamena F, Seeberger PH. Synthetic Glycosylphosphatidylinositol as Tools for Glycoparasitology Research. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2010; 14:445-54. [DOI: 10.1089/omi.2009.0138] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Nahid Azzouz
- Max Planck Institute of Colloids and Interfaces, Department of Biomolecular Systems, Research Campus, Golm, Germany, and Free University Berlin, Berlin, Germany
| | - Faustin Kamena
- Max Planck Institute of Colloids and Interfaces, Department of Biomolecular Systems, Research Campus, Golm, Germany, and Free University Berlin, Berlin, Germany
| | - Peter H. Seeberger
- Max Planck Institute of Colloids and Interfaces, Department of Biomolecular Systems, Research Campus, Golm, Germany, and Free University Berlin, Berlin, Germany
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Chandra S, Ruhela D, Deb A, Vishwakarma RA. Glycobiology of theLeishmaniaparasite and emerging targets for antileishmanial drug discovery. Expert Opin Ther Targets 2010; 14:739-57. [DOI: 10.1517/14728222.2010.495125] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Seeber F, Soldati-Favre D. Metabolic Pathways in the Apicoplast of Apicomplexa. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 281:161-228. [DOI: 10.1016/s1937-6448(10)81005-6] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Rodríguez AE, Couto A, Echaide I, Schnittger L, Florin-Christensen M. Babesia bovis contains an abundant parasite-specific protein-free glycerophosphatidylinositol and the genes predicted for its assembly. Vet Parasitol 2009; 167:227-35. [PMID: 19833438 DOI: 10.1016/j.vetpar.2009.09.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Autonomous glycosylphosphatidylinositol (GPI) molecules (also protein-free GPIs or free GPIs) have been reported to be particularly abundant in some parasitic protozoa and mediate strong immunomodulatory effects on the host immune system. In the work at hand we have investigated the existence of free GPIs in Babesia bovis. Comparative thin layer chromatographic analysis of the protein-free glycolipid fraction of in vitro cultured B. bovis merozoites and erythrocyte membranes demonstrated the presence of an abundant parasite-specific band. Its chemical analysis revealed a GPI species containing a chain of two mannose residues, N-glucosamine and non-acylated inositol. The lipid moiety linked to inositol was diacylglycerol. The total fatty acid composition showed predominantly long-carbon chain molecules (12% of C(22:0) and 45% of C(24:0)). The potential of B. bovis to assemble the presented free GPI species was verified by the existence of seven genes in its genome that putatively encode the following GPI biosynthetic enzymes: PI N-acetyl-GlcN-transferase (PIG-A and GPI-1), N-acetyl-GlcN-PI-de-N-acetylase (PIG-L), acyltransferase (PIG-W), dolichyl-phosphate mannosyl transferase (DPM-1), GPI mannosyltransferase I (PIG-M), and GPI mannosyltransferase II (PIG-V). GPI biosynthesis is vital for the intraerythrocytic parasite stage as mannosamine, an inhibitor of GPI biosynthesis, impaired in vitro growth of B. bovis merozoites. Absence of the vast majority of N-glycan metabolism encoding genes in the B. bovis genome underscores that the growth inhibitory effect of mannosamine is attributable to its interference with GPI biosynthesis and not with assembly of N-linked oligosaccharides, as has been described for higher eukaryotes. Elucidation of the structure and biosynthesis of GPI may allow to facilitate the development of future immune interventions against bovine babesiosis.
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Chapter 9 GPIs of Apicomplexan Protozoa. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s1874-6047(09)26009-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Stuart K, Brun R, Croft S, Fairlamb A, Gürtler RE, McKerrow J, Reed S, Tarleton R. Kinetoplastids: related protozoan pathogens, different diseases. J Clin Invest 2008; 118:1301-10. [PMID: 18382742 PMCID: PMC2276762 DOI: 10.1172/jci33945] [Citation(s) in RCA: 394] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Kinetoplastids are a group of flagellated protozoans that include the species Trypanosoma and Leishmania, which are human pathogens with devastating health and economic effects. The sequencing of the genomes of some of these species has highlighted their genetic relatedness and underlined differences in the diseases that they cause. As we discuss in this Review, steady progress using a combination of molecular, genetic, immunologic, and clinical approaches has substantially increased understanding of these pathogens and important aspects of the diseases that they cause. Consequently, the paths for developing additional measures to control these "neglected diseases" are becoming increasingly clear, and we believe that the opportunities for developing the drugs, diagnostics, vaccines, and other tools necessary to expand the armamentarium to combat these diseases have never been better.
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Affiliation(s)
- Ken Stuart
- Seattle Biomedical Research Institute, Seattle, Washington, USA.
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Silveira H, Ramos S, Abrantes P, Lopes LF, do Rosario VE, Abrahamsen MS. Effect of chloroquine on gene expression of Plasmodium yoelii nigeriensis during its sporogonic development in the mosquito vector. Malar J 2007; 6:84. [PMID: 17605769 PMCID: PMC1940257 DOI: 10.1186/1475-2875-6-84] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Accepted: 07/02/2007] [Indexed: 12/04/2022] Open
Abstract
Background The anti-malarial chloroquine can modulate the outcome of infection during the Plasmodium sporogonic development, interfering with Plasmodium gene expression and subsequently, with transmission. The present study sets to identify Plasmodium genes that might be regulated by chloroquine in the mosquito vector. Methods Differential display RT-PCR (DDRT-PCR) was used to identify genes expressed during the sporogonic cycle that are regulated by exposure to chloroquine. Anopheles stephensi mosquitoes were fed on Plasmodium yoelii nigeriensis-infected mice. Three days post-infection, mosquitoes were fed a non-infectious blood meal from mice treated orally with 50 mg/kg chloroquine. Two differentially expressed Plasmodium transcripts (Pyn_chl091 and Pyn_chl055) were further characterized by DNA sequencing and real-time PCR analysis. Results Both transcripts were represented in Plasmodium EST databases, but displayed no homology with any known genes. Pyn_chl091 was upregulated by day 18 post infection when the mosquito had a second blood meal. However, when the effect of chloroquine on that transcript was investigated during the erythrocytic cycle, no significant differences were observed. Although slightly upregulated by chloroquine exposure the expression of Pyn_chl055 was more affected by development, increasing towards the end of the sporogonic cycle. Transcript abundance of Pyn_chl055 was reduced when erythrocytic stages were treated with chloroquine. Conclusion Chloroquine increased parasite load in mosquito salivary glands and interferes with the expression of at least two Plasmodium genes. The transcripts identified contain putative signal peptides and transmembrane domains suggesting that these proteins, due to their location, are targets of chloroquine (not as an antimalarial) probably through cell trafficking and recycling.
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Affiliation(s)
- Henrique Silveira
- Centro de Malária e Outras Doenças Tropicais, UEI Malária, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal
| | - Susana Ramos
- Centro de Malária e Outras Doenças Tropicais, UEI Malária, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal
| | - Patrícia Abrantes
- Centro de Malária e Outras Doenças Tropicais, UEI Malária, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal
| | - Luís Filipe Lopes
- Centro de Malária e Outras Doenças Tropicais, UEI Malária, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal
| | - Virgílio E do Rosario
- Centro de Malária e Outras Doenças Tropicais, UEI Malária, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal
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Daniellou R, Palmer DRJ. Appel–Lee synthesis of glycosyl inositols, substrates for inositol dehydrogenase from Bacillus subtilis. Carbohydr Res 2006; 341:2145-50. [PMID: 16729989 DOI: 10.1016/j.carres.2006.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 05/02/2006] [Accepted: 05/03/2006] [Indexed: 11/15/2022]
Abstract
We recently reported that inositol dehydrogenase (EC 1.1.1.18) from Bacillus subtilis can catalyze the highly stereoselective oxidation of 1l-4-O-substituted myo-inositol derivatives, as well as disaccharides melibiose and isomaltose, but not gentiobiose or maltose, consistent with the requirement of an alpha-(1-->6) linkage. We believed that the enzyme might therefore catalyze efficient stereoselective oxidation of the appropriate alpha-linked glycosyl inositols. We have synthesized alpha-D-glucopyranosyl-(1-->4)-(DL)-myo-inositol and alpha-d-galactopyranosyl-(1-->4)-(DL)-myo-inositol using the Appel-Lee protocol to couple benzyl-protected glycosyl donors to protected inositols. This method failed in our hands using glycosyl donors derived from D-mannose and 2-azido-2-deoxy-D-glucose. When myo-inositol 1,3,5-monoorthoformate is used as the acceptor, the reaction is regiospecific for the 4/6-position. We report here the mildest conditions known for the removal of the orthoformate group. 2-Azido-2-deoxy-alpha-D-glucopyranosyl-(1-->4)-(DL)-myo-inositol was synthesized using the trichloroacetimidate derivative as the donor, and all three pseudo-disaccharides were substrates for inositol dehydrogenase. The glucopyranosyl and galactopyranosyl derivatives displayed apparent second-order rate constants comparable to that of myo-inositol.
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Affiliation(s)
- Richard Daniellou
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
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Martin KL, Smith TK. The glycosylphosphatidylinositol (GPI) biosynthetic pathway of bloodstream-form Trypanosoma brucei is dependent on the de novo synthesis of inositol. Mol Microbiol 2006; 61:89-105. [PMID: 16824097 PMCID: PMC3793301 DOI: 10.1111/j.1365-2958.2006.05216.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In bloodstream-form Trypanosoma brucei (the causative agent of African sleeping sickness) the glycosylphosphatidylinositol (GPI) anchor biosynthetic pathway has been validated genetically and chemically as a drug target. The conundrum that GPI anchors could not be in vivo labelled with [3H]-inositol led us to hypothesize that de novo synthesis was responsible for supplying myo-inositol for phosphatidylinositol (PI) destined for GPI synthesis. The rate-limiting step of the de novo synthesis is the isomerization of glucose 6-phosphate to 1-D-myo-inositol-3-phosphate, catalysed by a 1-D-myo-inositol-3-phosphate synthase (INO1). When grown under non-permissive conditions, a conditional double knockout demonstrated that INO1 is an essential gene in bloodstream-form T. brucei. It also showed that the de novo synthesized myo-inositol is utilized to form PI, which is preferentially used in GPI biosynthesis. We also show for the first time that extracellular myo-inositol can in fact be used in GPI formation although to a limited extent. Despite this, extracellular inositol cannot compensate for the deletion of INO1. Supporting these results, there was no change in PI levels in the conditional double knockout cells grown under non-permissive conditions, showing that perturbation of growth is due to a specific lack of de novo synthesized myo-inositol and not a general inositol-less death. These results suggest that there is a distinction between de novo synthesized myo-inositol and that from the extracellular environment.
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Affiliation(s)
- Kirstee L. Martin
- Division of Biological Chemistry and Molecular Microbiology, The School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Terry K. Smith
- Division of Biological Chemistry and Molecular Microbiology, The School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
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Azzouz N, de Macedo CS, Ferguson MAJ, Smith TK, Schwarz RT. Mannosamine can replace glucosamine in glycosylphosphatidylinositols of Plasmodium falciparum in vitro. Mol Biochem Parasitol 2005; 142:12-24. [PMID: 15885822 DOI: 10.1016/j.molbiopara.2005.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2004] [Revised: 01/17/2005] [Accepted: 02/15/2005] [Indexed: 11/21/2022]
Abstract
Mannosamine (2-deoxy-2-amino-D-mannose) is unable to block GPI biosynthesis in Plasmodium falciparum: neither parasite development nor GPI biosynthesis were blocked by mannosamine treatment in P. falciparum cultures. Further, it was shown by metabolic labeling with [3H]mannosamine and subsequent monosaccharide analysis by high pH anion exchange chromatography that mannosamine is converted at a high rate into glucosamine. Both mannosamine and glucosamine are incorporated into P. falciparum glycolipids, but the characterization of mannosamine-labeled glycolipids synthesized in vivo proved difficult. Therefore, a cell-free system was developed to investigate the incorporation of [3H]mannosamine into glycolipids in P. falciparum. It was observed that mannosamine is incorporated in vitro into P. falciparum glycolipids, which possess a phosphate group. Chemical (nitrous acid deamination, mild acid hydrolysis and alkaline hydrolysis) and enzymatic (PI-PLC) treatments of [3H]mannosamine-labeled glycolipids synthesized in vitro showed the presence of GPIs. Further analyses by Bio-Gel P4 size-exclusion chromatography and HPAEC demonstrated the presence of a mannosamine-containing GPI-like structures, where mannosamine is incorporated instead of glucosamine, i.e. Man3-ManN-PI. This utilization of mannosamine is novel and not been described for any other cellular or parasitic system.
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Affiliation(s)
- Nahid Azzouz
- Institut für Virologie, Med. Zentrum für Hygiene und Medizinische Mikrobiologie, Philipps-Universität Marburg, Robert-Koch-Strasse 17, D-35037 Marburg, Germany
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Urbaniak MD, Crossman A, Chang T, Smith TK, van Aalten DMF, Ferguson MAJ. The N-acetyl-D-glucosaminylphosphatidylinositol De-N-acetylase of glycosylphosphatidylinositol biosynthesis is a zinc metalloenzyme. J Biol Chem 2005; 280:22831-8. [PMID: 15817455 DOI: 10.1074/jbc.m502402200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The de-N-acetylation of N-acetyl-D-glucosaminylphosphatidylinositol (GlcNAc-PI) is the second step of mammalian and trypanosomal glycosylphosphatidylinositol biosynthesis. Glycosylphosphatidylinositol biosynthesis is essential for Trypanosoma brucei, the causative agent of African sleeping sickness, and GlcNAc-PI de-N-acetylase has previously been validated as a drug target. Inhibition of the trypanosome cell-free system and recombinant rat GlcNAc-PI de-N-acetylase by divalent metal cation chelators demonstrates that a tightly bound divalent metal cation is essential for activity. Reconstitution of metal-free GlcNAc-PI de-N-acetylase with divalent metal cations restores activity in the order Zn(2+) > Cu(2+) > Ni(2+) > Co(2+) > Mg(2+). Site-directed mutagenesis and homology modeling were used to identify active site residues and postulate a mechanism of action. The characterization of GlcNAc-PI de-N-acetylase as a zinc metalloenzyme will facilitate the rational design of anti-protozoan parasite drugs.
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Affiliation(s)
- Michael D Urbaniak
- Division of Biological Chemistry and Molecular Microbiology, Wellcome Trust Biocentre, The University of Dundee, Scotland, UK
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Boutlis CS, Riley EM, Anstey NM, de Souza JB. Glycosylphosphatidylinositols in malaria pathogenesis and immunity: potential for therapeutic inhibition and vaccination. Curr Top Microbiol Immunol 2005; 297:145-85. [PMID: 16265905 DOI: 10.1007/3-540-29967-x_5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Glycosylphosphatidylinositols (GPIs) are found in the outer cell membranes of all eukaryotes. GPIs anchor a diverse range of proteins to the surface of Plasmodium falciparum, but may also exist free of protein attachment. In vitro and in vivo studies have established GPIs as likely candidate toxins in malaria, consistent with the prevailing paradigm that attributes induction of inflammatory cytokines, fever and other pathology to parasite toxins released when schizonts rupture. Although evolutionarily conserved, sufficient structural differences appear to exist that impart upon plasmodial GPIs the ability to activate second messengers in mammalian cells and elicit immune responses. In populations exposed to P. falciparum, the antibody response to purified GPIs is characterised by a predominance of immunoglobulin (Ig)G over IgM and an increase in the prevalence, level and persistence of responses with increasing age. It remains unclear, however, if these antibodies or other cellular responses to GPIs mediate anti-toxic immunity in humans; anti-toxic immunity may comprise either reduction in the severity of disease or maintenance of the malaria-tolerant state (i.e. persistent asymptomatic parasitaemia). P. falciparum GPIs are potentially amenable to specific therapeutic inhibition and vaccination; more needs to be known about their dual roles in malaria pathogenesis and protection for these strategies to succeed.
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Affiliation(s)
- C S Boutlis
- International Health Program, Infectious Diseases Division, Menzies School of Health Research, P.O. Box 41096, 0811 Casuarina, NT, Australia.
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Smith TK, Crossman A, Brimacombe JS, Ferguson MAJ. Chemical validation of GPI biosynthesis as a drug target against African sleeping sickness. EMBO J 2004; 23:4701-8. [PMID: 15526036 PMCID: PMC533043 DOI: 10.1038/sj.emboj.7600456] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Accepted: 10/01/2004] [Indexed: 11/09/2022] Open
Abstract
It has been suggested that compounds affecting glycosylphosphatidylinositol (GPI) biosynthesis in bloodstream form Trypanosoma brucei should be trypanocidal. We describe cell-permeable analogues of a GPI intermediate that are toxic to this parasite but not to human cells. These analogues are metabolized by the T. brucei GPI pathway, but not by the human pathway. Closely related nonmetabolizable analogues have no trypanocidal activity. This represents the first direct chemical validation of the GPI biosynthetic pathway as a drug target against African human sleeping sickness. The results should stimulate further inhibitor design and synthesis and encourage the search for inhibitors in natural product and synthetic compound libraries.
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Affiliation(s)
- Terry K Smith
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, Scotland, UK
| | - Arthur Crossman
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, Scotland, UK
| | - John S Brimacombe
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, Scotland, UK
| | - Michael A J Ferguson
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, Scotland, UK
- Department of Biochemistry, Medical Sciences Institute, University of Dundee, Dundee DD1 5EH, Scotland, UK. Tel.: +44 1382 344 219; Fax: +44 1382 345764; E-mail:
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