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An RNA Interference (RNAi) Toolkit and Its Utility for Functional Genetic Analysis of Leishmania ( Viannia). Genes (Basel) 2022; 14:genes14010093. [PMID: 36672832 PMCID: PMC9858808 DOI: 10.3390/genes14010093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/13/2022] [Accepted: 12/22/2022] [Indexed: 12/30/2022] Open
Abstract
RNA interference (RNAi) is a powerful tool whose efficacy against a broad range of targets enables functional genetic tests individually or systematically. However, the RNAi pathway has been lost in evolution by a variety of eukaryotes including most Leishmania sp. RNAi was retained in species of the Leishmania subgenus Viannia, and here we describe the development, optimization, and application of RNAi tools to the study of L. (Viannia) braziliensis (Lbr). We developed vectors facilitating generation of long-hairpin or "stem-loop" (StL) RNAi knockdown constructs, using GatewayTM site-specific recombinase technology. A survey of applications of RNAi in L. braziliensis included genes interspersed within multigene tandem arrays such as quinonoid dihydropteridine reductase (QDPR), a potential target or modulator of antifolate sensitivity. Other tests include genes involved in cell differentiation and amastigote proliferation (A600), and essential genes of the intraflagellar transport (IFT) pathway. We tested a range of stem lengths targeting the L. braziliensis hypoxanthine-guanine phosphoribosyl transferase (HGPRT) and reporter firefly luciferase (LUC) genes and found that the efficacy of RNAi increased with stem length, and fell off greatly below about 128 nt. We used the StL length dependency to establish a useful 'hypomorphic' approach not possible with other gene ablation strategies, with shorter IFT140 stems yielding viable cells with compromised flagellar morphology. We showed that co-selection for RNAi against adenine phosphoryl transferase (APRT1) using 4-aminopyrazolpyrimidine (APP) could increase the efficacy of RNAi against reporter constructs, a finding that may facilitate improvements in future work. Thus, for many genes, RNAi provides a useful tool for studying Leishmania gene function with some unique advantages.
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Prokopchuk G, Korytář T, Juricová V, Majstorović J, Horák A, Šimek K, Lukeš J. Trophic flexibility of marine diplonemids - switching from osmotrophy to bacterivory. THE ISME JOURNAL 2022; 16:1409-1419. [PMID: 35042972 PMCID: PMC9039065 DOI: 10.1038/s41396-022-01192-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 12/23/2021] [Accepted: 01/06/2022] [Indexed: 05/03/2023]
Abstract
Diplonemids are one of the most abundant groups of heterotrophic planktonic microeukaryotes in the world ocean and, thus, are likely to play an essential role in marine ecosystems. So far, only few species have been introduced into a culture, allowing basic studies of diplonemid genetics, morphology, ultrastructure, metabolism, as well as endosymbionts. However, it remains unclear whether these heterotrophic flagellates are parasitic or free-living and what are their predominant dietary patterns and preferred food items. Here we show that cultured diplonemids, maintained in an organic-rich medium as osmotrophs, can gradually switch to bacterivory as a sole food resource, supporting positive growth of their population, even when fed with a low biovolume of bacteria. We further observed remarkable differences in species-specific feeding patterns, size-selective grazing preferences, and distinct feeding strategies. Diplonemids can discriminate between low-quality food items and inedible particles, such as latex beads, even after their ingestion, by discharging them in the form of large waste vacuoles. We also detected digestion-related endogenous autofluorescence emitted by lysosomes and the activity of a melanin-like material. We present the first evidence that these omnipresent protists possess an opportunistic lifestyle that provides a considerable advantage in the generally food resource-limited marine environments.
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Affiliation(s)
- Galina Prokopchuk
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
| | - Tomáš Korytář
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Fisheries and Protection of Waters, University of South Bohemia, České Budějovice, Czech Republic
| | - Valéria Juricová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Jovana Majstorović
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Aleš Horák
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Karel Šimek
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Hydrobiology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
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3
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Yao Y, Shi L, Xiao W, Guo S, Liu S, Li H, Zhang S. Phenylalanine hydroxylase (PAH) plays a positive role during WSSV and Vibrio parahaemolyticus infection in Litopenaeus vannamei. FISH & SHELLFISH IMMUNOLOGY 2022; 120:515-525. [PMID: 34952194 DOI: 10.1016/j.fsi.2021.12.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/15/2021] [Accepted: 12/18/2021] [Indexed: 06/14/2023]
Abstract
Phenylalanine hydroxylase (PAH) is involved in immune defence reactions by providing the starting material, tyrosine, to synthesise catecholamines and melanin. PAH is an important metabolic enzyme of aromatic amino acids and the rate-limiting enzyme in the hydroxylation of amino acid phenylalanine to tyrosine. In the present study, a PAH gene, LvPAH, was cloned and identified from Litopenaeus vannamei. The open reading frame (ORF) of LvPAH was 1383 bp, encoding a protein of 460 amino acids comprised of an ACT domain and a Biopterin_H domain. LvPAH was constitutively expressed in healthy L. vannamei, with the highest expression levels in the eyestalk and the lowest in the hepatopancreas. Both white spot syndrome virus (WSSV) and Vibrio parahaemolyticus infection upregulated LvPAH expression in hemocytes, hepatopancreas and gills of L. vannamei. Inhibition of LvPAH resulted in a significantly lower survival rate of L. vannamei after WSSV infection than the control group, consistent with the observation that WSSV viral load was significantly higher in LvPAH-silenced L. vannamei. After a V. parahaemolyticus challenge, there was no significant difference between the survival rate of LvPAH-silenced and the control L. vannamei. However, the load of V. parahaemolyticus in LvPAH-silenced L. vannamei was significantly higher than the control population for L. vannamei. The effect of LvPAH on L. vannamei from a neuroendocrinological perspective was assessed by measuring l-DOPA, dopamine (DA) and noradrenaline (NE) levels in the hemocytes after the knockdown of LvPAH. The results showed that phenoloxidase (PO), l-DOPA and DA levels in the hemolymph of LvPAH-silenced L. vannamei were significantly decreased starting from 24hpi. In contrast, the NE levels in the hemolymph of shrimp decreased significantly at first and then increased. The results suggest that LvPAH may play an important role in antiviral and bacterial immunity in L. vannamei.
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Affiliation(s)
- Yuanmao Yao
- College of Fisheries, Guangdong Ocean University, Zhanjiang, China
| | - Lili Shi
- College of Fisheries, Guangdong Ocean University, Zhanjiang, China
| | - Wei Xiao
- College of Fisheries, Guangdong Ocean University, Zhanjiang, China
| | - Sixin Guo
- College of Fisheries, Guangdong Ocean University, Zhanjiang, China
| | - Saiya Liu
- College of Fisheries, Guangdong Ocean University, Zhanjiang, China
| | - Haoyang Li
- State Key Laboratory of Biocontrol, School of Marine Sciences, Sun Yat-sen University, Guangzhou, China
| | - Shuang Zhang
- College of Fisheries, Guangdong Ocean University, Zhanjiang, China; Key Laboratory of Aquatic, Livestock and Poultry Feed Science and Technology in South China, Ministry of Agriculture, Zhanjiang, China; Aquatic Animals Precision Nutrition and High Efficiency Feed Engineering Research Center of Guangdong Province, Zhanjiang, China.
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Moroz LL, Romanova DY, Kohn AB. Neural versus alternative integrative systems: molecular insights into origins of neurotransmitters. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190762. [PMID: 33550949 PMCID: PMC7935107 DOI: 10.1098/rstb.2019.0762] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2020] [Indexed: 12/18/2022] Open
Abstract
Transmitter signalling is the universal chemical language of any nervous system, but little is known about its early evolution. Here, we summarize data about the distribution and functions of neurotransmitter systems in basal metazoans as well as outline hypotheses of their origins. We explore the scenario that neurons arose from genetically different populations of secretory cells capable of volume chemical transmission and integration of behaviours without canonical synapses. The closest representation of this primordial organization is currently found in Placozoa, disk-like animals with the simplest known cell composition but complex behaviours. We propose that injury-related signalling was the evolutionary predecessor for integrative functions of early transmitters such as nitric oxide, ATP, protons, glutamate and small peptides. By contrast, acetylcholine, dopamine, noradrenaline, octopamine, serotonin and histamine were recruited as canonical neurotransmitters relatively later in animal evolution, only in bilaterians. Ligand-gated ion channels often preceded the establishment of novel neurotransmitter systems. Moreover, lineage-specific diversification of neurotransmitter receptors occurred in parallel within Cnidaria and several bilaterian lineages, including acoels. In summary, ancestral diversification of secretory signal molecules provides unique chemical microenvironments for behaviour-driven innovations that pave the way to complex brain functions and elementary cognition. This article is part of the theme issue 'Basal cognition: multicellularity, neurons and the cognitive lens'.
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Affiliation(s)
- Leonid L. Moroz
- Department of Neuroscience, McKnight Brain Institute and Whitney laboratory, University of Florida, 9505 Ocean shore Blvd, St Augustine, FL 32080, USA
| | - Daria Y. Romanova
- Laboratory of Cellular Neurobiology of Learning, Institute of Higher Nervous Activity and Neurophysiology of RAS, 5A Butlerova Street, Moscow 117485, Russia
| | - Andrea B. Kohn
- Department of Neuroscience, McKnight Brain Institute and Whitney laboratory, University of Florida, 9505 Ocean shore Blvd, St Augustine, FL 32080, USA
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Targeting pteridine reductase 1 and dihydrofolate reductase: the old is a new trend for leishmaniasis drug discovery. Future Med Chem 2019; 11:2107-2130. [DOI: 10.4155/fmc-2018-0512] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Leishmaniasis is one of the major neglected tropical diseases in the world and it is considered endemic in 88 countries. This disease is transmitted by a Leishmania spp. infected sandfly and it may lead to cutaneous or systemic manifestations. The preconized treatment has low efficacy and there are cases of resistance to some drugs. Therefore, the search for new efficient molecular targets that can lead to the preparation of new drugs must be pursued. This review aims to evaluate both Leishmania enzymes PTR1 and DHFR-TS as potential drug targets, highlight their inhibitors and to discuss critically the use of chemoinformatics to elucidate interactions and propose new molecules against these enzymes.
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The Uptake and Metabolism of Amino Acids, and Their Unique Role in the Biology of Pathogenic Trypanosomatids. Pathogens 2018; 7:pathogens7020036. [PMID: 29614775 PMCID: PMC6027508 DOI: 10.3390/pathogens7020036] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 03/28/2018] [Accepted: 03/29/2018] [Indexed: 01/24/2023] Open
Abstract
Trypanosoma brucei, as well as Trypanosoma cruzi and more than 20 species of the genus Leishmania, form a group of flagellated protists that threaten human health. These organisms are transmitted by insects that, together with mammals, are their natural hosts. This implies that during their life cycles each of them faces environments with different physical, chemical, biochemical, and biological characteristics. In this work we review how amino acids are obtained from such environments, how they are metabolized, and how they and some of their intermediate metabolites are used as a survival toolbox to cope with the different conditions in which these parasites should establish the infections in the insects and mammalian hosts.
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Abstract
Transfection technology is an important tool in the investigation of gene function and the modulation of gene expression, thereby contributing to the advancement of basic cellular research, drug discovery, and target validation. Creation of the mutant cells through gene disruption and exogenous protein expression with noticeable phenotype like reporter genes are among other key applications. In this chapter, protocols for generating recombinant Leishmania expressing EGFP or EGFP-Luciferase and their applications are given in detail.
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Simonet P, Gaget K, Parisot N, Duport G, Rey M, Febvay G, Charles H, Callaerts P, Colella S, Calevro F. Disruption of phenylalanine hydroxylase reduces adult lifespan and fecundity, and impairs embryonic development in parthenogenetic pea aphids. Sci Rep 2016; 6:34321. [PMID: 27694983 PMCID: PMC5046115 DOI: 10.1038/srep34321] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/12/2016] [Indexed: 11/11/2022] Open
Abstract
Phenylalanine hydroxylase (PAH) is a key tyrosine-biosynthetic enzyme involved in neurological and melanin-associated physiological processes. Despite extensive investigations in holometabolous insects, a PAH contribution to insect embryonic development has never been demonstrated. Here, we have characterized, for the first time, the PAH gene in a hemimetabolous insect, the aphid Acyrthosiphon pisum. Phylogenetic and sequence analyses confirmed that ApPAH is closely related to metazoan PAH, exhibiting the typical ACT regulatory and catalytic domains. Temporal expression patterns suggest that ApPAH has an important role in aphid developmental physiology, its mRNA levels peaking at the end of embryonic development. We used parental dsApPAH treatment to generate successful knockdown in aphid embryos and to study its developmental role. ApPAH inactivation shortens the adult aphid lifespan and considerably affects fecundity by diminishing the number of nymphs laid and impairing embryonic development, with newborn nymphs exhibiting severe morphological defects. Using single nymph HPLC analyses, we demonstrated a significant tyrosine deficiency and a consistent accumulation of the upstream tyrosine precursor, phenylalanine, in defective nymphs, thus confirming the RNAi-mediated disruption of PAH activity. This study provides first insights into the role of PAH in hemimetabolous insects and demonstrates that this metabolic gene is essential for insect embryonic development.
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Affiliation(s)
- Pierre Simonet
- Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France
| | - Karen Gaget
- Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France
| | - Nicolas Parisot
- Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France
| | - Gabrielle Duport
- Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France
| | - Marjolaine Rey
- Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France
| | - Gérard Febvay
- Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France
| | - Hubert Charles
- Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France
| | - Patrick Callaerts
- KU Leuven, University of Leuven, Department of Human Genetics, Laboratory of Behavioral and Developmental Genetics, B-3000, Leuven, Belgium
- VIB Center for the Biology of Disease, B-3000, Leuven, Belgium
| | - Stefano Colella
- Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France
| | - Federica Calevro
- Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France
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Sardar AH, Jardim A, Ghosh AK, Mandal A, Das S, Saini S, Abhishek K, Singh R, Verma S, Kumar A, Das P. Genetic Manipulation of Leishmania donovani to Explore the Involvement of Argininosuccinate Synthase in Oxidative Stress Management. PLoS Negl Trop Dis 2016; 10:e0004308. [PMID: 26939071 PMCID: PMC4777552 DOI: 10.1371/journal.pntd.0004308] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 11/25/2015] [Indexed: 11/20/2022] Open
Abstract
Reactive oxygen and nitrogen species (ROS and RNS) produced by the phagocytic cells are the most common arsenals used to kill the intracellular pathogens. However, Leishmania, an intracellular pathogen, has evolved mechanisms to survive by counterbalancing the toxic oxygen metabolites produced during infection. Polyamines, the major contributor in this anti-oxidant machinery, are largely dependent on the availability of L-arginine in the intracellular milieu. Argininosuccinate synthase (ASS) plays an important role as the rate-limiting step required for converting L-citrulline to argininosuccinate to provide arginine for an assortment of metabolic processes. Leishmania produce an active ASS enzyme, yet it has an incomplete urea cycle as it lacks an argininosuccinate lyase (ASL). There is no evidence for endogenous synthesis of L-arginine in Leishmania, which suggests that these parasites salvage L-arginine from extracellular milieu and makes the biological function of ASS and the production of argininosuccinate in Leishmania unclear. Our previous quantitative proteomic analysis of Leishmania promastigotes treated with sub-lethal doses of ROS, RNS, or a combination of both, led to the identification of several differentially expressed proteins which included ASS. To assess the involvement of ASS in stress management, a mutant cell line with greatly reduced ASS activity was created by a double-targeted gene replacement strategy in L. donovani promastigote. Interestingly, LdASS is encoded by three copies of allele, but Western blot analysis showed the third allele did not appear to express ASS. The free thiol levels in the mutant LdASS-/-/+ cell line were decreased. Furthermore, the cell viability in L-arginine depleted medium was greatly attenuated on exposure to different stress environments and was adversely impacted in its ability to infect mice. These findings suggest that ASS is important for Leishmania donovani to counterbalance the stressed environments encountered during infection and can be targeted for chemotherapeutic purpose to treat visceral leishmaniasis.
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Affiliation(s)
- Abul Hasan Sardar
- Division of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Bihar, India
| | - Armando Jardim
- Institute of Parasitology and Centre for Host-Parasite Interactions, Macdonald Campus, McGill University, Quebec, Canada
| | - Ayan Kumar Ghosh
- Division of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Bihar, India
| | - Abhishek Mandal
- Division of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Bihar, India
| | - Sushmita Das
- Department of Microbiology, All India Institute of Medical Sciences, Bihar, India
| | - Savita Saini
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER), Bihar, India
| | - Kumar Abhishek
- Division of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Bihar, India
| | - Ruby Singh
- Division of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Bihar, India
| | - Sudha Verma
- Division of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Bihar, India
| | - Ajay Kumar
- Division of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Bihar, India
| | - Pradeep Das
- Division of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Bihar, India
- * E-mail:
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Westrop GD, Williams RAM, Wang L, Zhang T, Watson DG, Silva AM, Coombs GH. Metabolomic Analyses of Leishmania Reveal Multiple Species Differences and Large Differences in Amino Acid Metabolism. PLoS One 2015; 10:e0136891. [PMID: 26368322 PMCID: PMC4569581 DOI: 10.1371/journal.pone.0136891] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 08/09/2015] [Indexed: 01/09/2023] Open
Abstract
Comparative genomic analyses of Leishmania species have revealed relatively minor heterogeneity amongst recognised housekeeping genes and yet the species cause distinct infections and pathogenesis in their mammalian hosts. To gain greater information on the biochemical variation between species, and insights into possible metabolic mechanisms underpinning visceral and cutaneous leishmaniasis, we have undertaken in this study a comparative analysis of the metabolomes of promastigotes of L. donovani, L. major and L. mexicana. The analysis revealed 64 metabolites with confirmed identity differing 3-fold or more between the cell extracts of species, with 161 putatively identified metabolites differing similarly. Analysis of the media from cultures revealed an at least 3-fold difference in use or excretion of 43 metabolites of confirmed identity and 87 putatively identified metabolites that differed to a similar extent. Strikingly large differences were detected in their extent of amino acid use and metabolism, especially for tryptophan, aspartate, arginine and proline. Major pathways of tryptophan and arginine catabolism were shown to be to indole-3-lactate and arginic acid, respectively, which were excreted. The data presented provide clear evidence on the value of global metabolomic analyses in detecting species-specific metabolic features, thus application of this technology should be a major contributor to gaining greater understanding of how pathogens are adapted to infecting their hosts.
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Affiliation(s)
- Gareth D. Westrop
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Roderick A. M. Williams
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
- Institute of Biomedical and Environmental Health Research, University of the West of Scotland, Paisley, United Kingdom
| | - Lijie Wang
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Tong Zhang
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - David G. Watson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Ana Marta Silva
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Graham H. Coombs
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
- * E-mail:
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11
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Flydal MI, Martinez A. Phenylalanine hydroxylase: function, structure, and regulation. IUBMB Life 2013; 65:341-9. [PMID: 23457044 DOI: 10.1002/iub.1150] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 01/09/2013] [Indexed: 11/08/2022]
Abstract
Mammalian phenylalanine hydroxylase (PAH) catalyzes the rate-limiting step in the phenylalanine catabolism, consuming about 75% of the phenylalanine input from the diet and protein catabolism under physiological conditions. In humans, mutations in the PAH gene lead to phenylketonuria (PKU), and most mutations are mainly associated with PAH misfolding and instability. The established treatment for PKU is a phenylalanine-restricted diet and, recently, supplementation with preparations of the natural tetrahydrobiopterin cofactor also shows effectiveness for some patients. Since 1997 there has been a significant increase in the understanding of the structure, catalytic mechanism, and regulation of PAH by its substrate and cofactor, in addition to improved correlations between genotype and phenotype in PKU. Importantly, there has also been an increased number of studies on the structure and function of PAH from bacteria and lower eukaryote organisms, revealing an additional anabolic role of the enzyme in the synthesis of melanin-like pigments. In this review, we discuss these recent studies, which contribute to define the evolutionary adaptation of the PAH structure and function leading to sophisticated regulation for effective catabolic processing of phenylalanine in mammalian organisms.
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Affiliation(s)
- Marte I Flydal
- Department of Biomedicine and K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Jonas Lies vei 91, 5009-Bergen, Norway
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12
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Lakhal-Naouar I, Jardim A, Strasser R, Luo S, Kozakai Y, Nakhasi HL, Duncan RC. Leishmania donovani argininosuccinate synthase is an active enzyme associated with parasite pathogenesis. PLoS Negl Trop Dis 2012; 6:e1849. [PMID: 23094117 PMCID: PMC3475689 DOI: 10.1371/journal.pntd.0001849] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 08/22/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Gene expression analysis in Leishmania donovani (Ld) identified an orthologue of the urea cycle enzyme, argininosuccinate synthase (LdASS), that was more abundantly expressed in amastigotes than in promastigotes. In order to characterize in detail this newly identified protein in Leishmania, we determined its enzymatic activity, subcellular localization in the parasite and affect on virulence in vivo. METHODOLOGY/PRINCIPAL FINDINGS Two parasite cell lines either over expressing wild type LdASS or a mutant form (G128S) associated with severe cases of citrullinemia in humans were developed. In addition we also produced bacterially expressed recombinant forms of the same proteins. Our results demonstrated that LdASS has argininosuccinate synthase enzymatic activity that is abolished using an ASS specific inhibitor (MDLA: methyl-D-L-Aspartic acid). However, the mutant form of the protein is inactive. We demonstrate that though LdASS has a glycosomal targeting signal that binds the targeting apparatus in vitro, only a small proportion of the total cellular ASS is localized in a vesicle, as indicated by protection from protease digestion of the crude organelle fraction. The majority of LdASS was found to be in the cytosolic fraction that may include large cytosolic complexes as indicated by the punctate distribution in IFA. Surprisingly, comparison to known glycosomal proteins by IFA revealed that LdASS was located in a structure different from the known glycosomal vesicles. Significantly, parasites expressing a mutant form of LdASS associated with a loss of in vitro activity had reduced virulence in vivo in BALB/c mice as demonstrated by a significant reduction in the parasite load in spleen and liver. CONCLUSION/SIGNIFICANCE Our study suggests that LdASS is an active enzyme, with unique localization and essential for parasite survival and growth in the mammalian host. Based on these observations LdASS could be further explored as a potential drug target.
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Affiliation(s)
- Ines Lakhal-Naouar
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research (CBER), Food and Drug Administration (FDA), Bethesda, Maryland, United States of America
| | - Armando Jardim
- Institute of Parasitology, McGill University and the Centre for Host-Parasite Interactions, Quebec, Canada
| | - Rona Strasser
- Institute of Parasitology, McGill University and the Centre for Host-Parasite Interactions, Quebec, Canada
| | - Shen Luo
- Laboratory of Chemistry, Division of Therapeutic Proteins, Center for Drug Evaluation and Research (CDER), Food and Drug Administration (FDA), Bethesda, Maryland, United States of America
| | - Yukiko Kozakai
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research (CBER), Food and Drug Administration (FDA), Bethesda, Maryland, United States of America
| | - Hira L. Nakhasi
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research (CBER), Food and Drug Administration (FDA), Bethesda, Maryland, United States of America
| | - Robert C. Duncan
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research (CBER), Food and Drug Administration (FDA), Bethesda, Maryland, United States of America
- * E-mail:
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Ong HB, Sienkiewicz N, Wyllie S, Fairlamb AH. Dissecting the metabolic roles of pteridine reductase 1 in Trypanosoma brucei and Leishmania major. J Biol Chem 2011; 286:10429-38. [PMID: 21239486 PMCID: PMC3060496 DOI: 10.1074/jbc.m110.209593] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Leishmania parasites are pteridine auxotrophs that use an NADPH-dependent pteridine reductase 1 (PTR1) and NADH-dependent quinonoid dihydropteridine reductase (QDPR) to salvage and maintain intracellular pools of tetrahydrobiopterin (H4B). However, the African trypanosome lacks a credible candidate QDPR in its genome despite maintaining apparent QDPR activity. Here we provide evidence that the NADH-dependent activity previously reported by others is an assay artifact. Using an HPLC-based enzyme assay, we demonstrate that there is an NADPH-dependent QDPR activity associated with both TbPTR1 and LmPTR1. The kinetic properties of recombinant PTR1s are reported at physiological pH and ionic strength and compared with LmQDPR. Specificity constants (kcat/Km) for LmPTR1 are similar with dihydrobiopterin (H2B) and quinonoid dihydrobiopterin (qH2B) as substrates and about 20-fold lower than LmQDPR with qH2B. In contrast, TbPTR1 shows a 10-fold higher kcat/Km for H2B over qH2B. Analysis of Trypanosoma brucei isolated from infected rats revealed that H4B (430 nm, 98% of total biopterin) was the predominant intracellular pterin, consistent with a dual role in the salvage and regeneration of H4B. Gene knock-out experiments confirmed this: PTR1-nulls could only be obtained from lines overexpressing LmQDPR with H4B as a medium supplement. These cells grew normally with H4B, which spontaneously oxidizes to qH2B, but were unable to survive in the absence of pterin or with either biopterin or H2B in the medium. These findings establish that PTR1 has an essential and dual role in pterin metabolism in African trypanosomes and underline its potential as a drug target.
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Affiliation(s)
- Han B Ong
- Division of Biological Chemistry & Drug Discovery, College of Life Sciences, University of Dundee, Wellcome Trust Biocentre, Dundee DD1 5EH, Scotland, United Kingdom
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