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YİĞİT U, KIRZIOĞLU FY, ÖZMEN Ö, UĞUZ YA. Effects of LDD and CAPE administration on total antioxidant and total oxidant levels in experimental periodontitis model of rat brain. ACTA MEDICA ALANYA 2022. [DOI: 10.30565/medalanya.1052586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Santi AMM, Murta SMF. Impact of Genetic Diversity and Genome Plasticity of Leishmania spp. in Treatment and the Search for Novel Chemotherapeutic Targets. Front Cell Infect Microbiol 2022; 12:826287. [PMID: 35141175 PMCID: PMC8819175 DOI: 10.3389/fcimb.2022.826287] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/04/2022] [Indexed: 11/21/2022] Open
Abstract
Leishmaniasis is one of the major public health concerns in Latin America, Africa, Asia, and Europe. The absence of vaccines for human use and the lack of effective vector control programs make chemotherapy the main strategy to control all forms of the disease. However, the high toxicity of available drugs, limited choice of therapeutic agents, and occurrence of drug-resistant parasite strains are the main challenges related to chemotherapy. Currently, only a small number of drugs are available for leishmaniasis treatment, including pentavalent antimonials (SbV), amphotericin B and its formulations, miltefosine, paromomycin sulphate, and pentamidine isethionate. In addition to drug toxicity, therapeutic failure of leishmaniasis is a serious concern. The occurrence of drug-resistant parasites is one of the causes of therapeutic failure and is closely related to the diversity of parasites in this genus. Owing to the enormous plasticity of the genome, resistance can occur by altering different metabolic pathways, demonstrating that resistance mechanisms are multifactorial and extremely complex. Genetic variability and genome plasticity cause not only the available drugs to have limitations, but also make the search for new drugs challenging. Here, we examined the biological characteristics of parasites that hinder drug discovery.
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Testing the CRISPR-Cas9 and glmS ribozyme systems in Leishmania tarentolae. Mol Biochem Parasitol 2020; 241:111336. [PMID: 33166572 DOI: 10.1016/j.molbiopara.2020.111336] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/25/2020] [Accepted: 10/28/2020] [Indexed: 02/03/2023]
Abstract
Leishmania parasites include important pathogens and model organisms and are even used for the production of recombinant proteins. However, functional genomics and the characterization of essential genes are often limited in Leishmania because of low-throughput technologies for gene disruption or tagging and the absence of components for RNA interference. Here, we tested the T7 RNA polymerase-dependent CRISPR-Cas9 system by Beneke et al. and the glmS ribozyme-based knock-down system in the model parasite Leishmania tarentolae. We successfully deleted two reference genes encoding the flagellar motility factor Pf16 and the salvage-pathway enzyme adenine phosphoribosyltransferase, resulting in immotile and drug-resistant parasites, respectively. In contrast, we were unable to disrupt the gene encoding the mitochondrial flavoprotein Erv. Cultivation of L. tarentolae in standard BHI medium resulted in a constitutive down-regulation of an episomal mCherry-glmS reporter by 40 to 60%. For inducible knock-downs, we evaluated the growth of L. tarentolae in alternative media and identified supplemented MEM, IMDM and McCoy's 5A medium as candidates. Cultivation in supplemented MEM allowed an inducible, glucosamine concentration-dependent down-regulation of the episomal mCherry-glmS reporter by more than 70%. However, chromosomal glmS-tagging of the genes encoding Pf16, adenine phosphoribosyltransferase or Erv did not reveal a knock-down phenotype. Our data demonstrate the suitability of the CRISPR-Cas9 system for the disruption and tagging of genes in L. tarentolae as well as the limitations of the glmS system, which was restricted to moderate efficiencies for episomal knock-downs and caused no detectable phenotype for chromosomal knock-downs.
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Yagoubat A, Corrales RM, Bastien P, Lévêque MF, Sterkers Y. Gene Editing in Trypanosomatids: Tips and Tricks in the CRISPR-Cas9 Era. Trends Parasitol 2020; 36:745-760. [DOI: 10.1016/j.pt.2020.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/19/2020] [Accepted: 06/30/2020] [Indexed: 12/22/2022]
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Niemirowicz GT, Cazzulo JJ, Álvarez VE, Bouvier LA. Simplified inducible system for Trypanosoma brucei. PLoS One 2018; 13:e0205527. [PMID: 30308039 PMCID: PMC6181392 DOI: 10.1371/journal.pone.0205527] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 09/26/2018] [Indexed: 11/18/2022] Open
Abstract
Nowadays, most reverse genetics approaches in Trypanosoma brucei, a protozoan parasite of medical and veterinary importance, rely on pre-established cell lines. Consequently, inducible experimentation is reduced to a few laboratory strains. Here we described a new transgene expression system based exclusively on endogenous transcription activities and a minimum set of regulatory components that can easily been adapted to different strains. The pTbFIX vectors are designed to contain the sequence of interest under the control of an inducible rRNA promoter along with a constitutive dicistronic unit encoding a nucleus targeted tetracycline repressor and puromycin resistance genes in a tandem “head-to-tail” configuration. Upon doxycycline induction, the system supports regulatable GFP expression (170 to 400 fold) in both bloodstream and procyclic T. brucei forms. Furthermore we have adapted the pTbFIX plasmid to perform RNAi experimentation. Lethal phenotypes, including α-tubulin and those corresponding to the enolase and clathrin heavy chain genes, were successfully recapitulated in procyclic and bloodstream parasites thus showing the versatility of this new tool.
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Affiliation(s)
- Gabriela T. Niemirowicz
- Instituto de Investigaciones Biotecnológicas (IIB) Dr. Rodolfo A. Ugalde, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
| | - Juan J. Cazzulo
- Instituto de Investigaciones Biotecnológicas (IIB) Dr. Rodolfo A. Ugalde, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
| | - Vanina E. Álvarez
- Instituto de Investigaciones Biotecnológicas (IIB) Dr. Rodolfo A. Ugalde, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
| | - León A. Bouvier
- Instituto de Investigaciones Biotecnológicas (IIB) Dr. Rodolfo A. Ugalde, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
- * E-mail:
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Duncan SM, Jones NG, Mottram JC. Recent advances in Leishmania reverse genetics: Manipulating a manipulative parasite. Mol Biochem Parasitol 2017. [DOI: 10.1016/j.molbiopara.2017.06.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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7
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Inducible protein stabilization system in Leishmania mexicana. Mol Biochem Parasitol 2017; 214:62-64. [DOI: 10.1016/j.molbiopara.2017.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 11/21/2022]
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Kraeva N, Ishemgulova A, Lukeš J, Yurchenko V. Tetracycline-inducible gene expression system in Leishmania mexicana. Mol Biochem Parasitol 2014; 198:11-3. [DOI: 10.1016/j.molbiopara.2014.11.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Revised: 11/10/2014] [Accepted: 11/14/2014] [Indexed: 01/08/2023]
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Abstract
Leishmania parasites cause a variety of devastating diseases in tropical areas around the world. Due to the lack of vaccines and limited availability of drugs, new therapeutic targets are urgently needed. A variety of genetic tools have been developed to investigate the complex biology of this parasite and its interactions with the host. One of the main techniques is the generation of knock-out parasites via targeted gene replacement, a process that takes advantage of the parasites ability to undergo homologous recombination. Studying the effect of gene deletions in vitro and in infectivity models in vivo allows understanding the function of a target gene and its potential as a therapeutic target. Other genetic manipulations available include episomal and chromosomal complementation and the generation of overproducer strains. However, there are also limitations, such as the lack of RNA interference machinery in most Leishmania species and limited options for inducible expression systems. The genomes of several Leishmania species have now been sequenced and will provide powerful resources in combination with the genetic tools that are available. The increasing knowledge of parasite biology and host parasite interactions derived from these studies will raise the number of potential therapeutic targets, which are sorely needed to combat leishmaniasis.
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Abstract
Trypanosomes are a group of protozoan eukaryotes, many of which are major parasites of humans and livestock. The genomes of trypanosomes and their modes of gene expression differ in several important aspects from those of other eukaryotic model organisms. Protein-coding genes are organized in large directional gene clusters on a genome-wide scale, and their polycistronic transcription is not generally regulated at initiation. Transcripts from these polycistrons are processed by global trans-splicing of pre-mRNA. Furthermore, in African trypanosomes, some protein-coding genes are transcribed by a multifunctional RNA polymerase I from a specialized extranucleolar compartment. The primary DNA sequence of the trypanosome genomes and their cellular organization have usually been treated as separate entities. However, it is becoming increasingly clear that in order to understand how a genome functions in a living cell, we will need to unravel how the one-dimensional genomic sequence and its trans-acting factors are arranged in the three-dimensional space of the eukaryotic nucleus. Understanding this cell biology of the genome will be crucial if we are to elucidate the genetic control mechanisms of parasitism. Here, we integrate the concepts of nuclear architecture, deduced largely from studies of yeast and mammalian nuclei, with recent developments in our knowledge of the trypanosome genome, gene expression, and nuclear organization. We also compare this nuclear organization to those in other systems in order to shed light on the evolution of nuclear architecture in eukaryotes.
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Kushnir S, Cirstea IC, Basiliya L, Lupilova N, Breitling R, Alexandrov K. Artificial linear episome-based protein expression system for protozoon Leishmania tarentolae. Mol Biochem Parasitol 2010; 176:69-79. [PMID: 21167214 DOI: 10.1016/j.molbiopara.2010.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 12/01/2010] [Accepted: 12/03/2010] [Indexed: 11/28/2022]
Abstract
The trypanosomatid protozoon Leishmania tarentolae is a well-established model organism for studying causative agents of several tropical diseases that was more recently developed as a host for recombinant protein production. Although several expression architectures based on foreign RNA polymerases have been established for this organism, all of them rely on integration of the expression cassette into the genome. Here, we exploit a new type of expression architecture based on linear elements. These expression vectors were propagated in Escherichia coli as circular plasmids and converted into linear episomes with telomere-like structures prior to transfection of L. tarentolae. Overexpression of recombinant proteins in transgenic organisms exceeding 10% of total cellular protein, one of the highest overexpression levels obtained in a eukaryotic organism for a cytosolic protein. We show that the linear elements are stably propagated in L. tarentolae cells over long periods of time (> 90 generations) without major changes in structure or expression yields. Overexpressing cultures can be obtained without clonal selection of the transfected cells. To establish the utility of the developed system for protein production in a parallelized format, we expressed 37 cytosolic, peripheral, and membrane proteins as fusions with EGFP in L. tarentolae using linear vectors. We detected the expression of 30 of these targets and describe the preparative purification of two arbitrarily selected proteins.
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Affiliation(s)
- Susanna Kushnir
- Department of Chemical Biology Max-Planck-Institute for Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
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Dortay H, Mueller-Roeber B. A highly efficient pipeline for protein expression in Leishmania tarentolae using infrared fluorescence protein as marker. Microb Cell Fact 2010; 9:29. [PMID: 20459748 PMCID: PMC2874516 DOI: 10.1186/1475-2859-9-29] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 05/10/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Leishmania tarentolae, a unicellular eukaryotic protozoan, has been established as a novel host for recombinant protein production in recent years. Current protocols for protein expression in Leishmania are, however, time consuming and require extensive lab work in order to identify well-expressing cell lines. Here we established an alternative protein expression work-flow that employs recently engineered infrared fluorescence protein (IFP) as a suitable and easy-to-handle reporter protein for recombinant protein expression in Leishmania. As model proteins we tested three proteins from the plant Arabidopsis thaliana, including a NAC and a type-B ARR transcription factor. RESULTS IFP and IFP fusion proteins were expressed in Leishmania and rapidly detected in cells by deconvolution microscopy and in culture by infrared imaging of 96-well microtiter plates using small cell culture volumes (2 microL - 100 microL). Motility, shape and growth of Leishmania cells were not impaired by intracellular accumulation of IFP. In-cell detection of IFP and IFP fusion proteins was straightforward already at the beginning of the expression pipeline and thus allowed early pre-selection of well-expressing Leishmania clones. Furthermore, IFP fusion proteins retained infrared fluorescence after electrophoresis in denaturing SDS-polyacrylamide gels, allowing direct in-gel detection without the need to disassemble cast protein gels. Thus, parameters for scaling up protein production and streamlining purification routes can be easily optimized when employing IFP as reporter. CONCLUSIONS Using IFP as biosensor we devised a protocol for rapid and convenient protein expression in Leishmania tarentolae. Our expression pipeline is superior to previously established methods in that it significantly reduces the hands-on-time and work load required for identifying well-expressing clones, refining protein production parameters and establishing purification protocols. The facile in-cell and in-gel detection tools built on IFP make Leishmania amenable for high-throughput expression of proteins from plant and animal sources.
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Affiliation(s)
- Hakan Dortay
- University of Potsdam, Institute of Biochemistry and Biology, Karl-Liebknecht-Strasse 24-25, Haus 20, Potsdam-Golm, Germany
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Abstract
A variety of recombinant protein expression systems have been developed for heterologous genes in both prokaryotic and eukaryotic systems such as bacteria, yeast, mammals, insects, transgenic animals, and plants. Recently Leishmania tarentolae, a trypanosomatid protozoan parasite of the white-spotted wall gecko (Tarentola annularis), has been suggested as candidate for heterologous genes expression. Trypanosomatidae are rich in glycoproteins, which can account for more than 10% of total protein; the oligosaccharide structures are similar to those of mammals with N-linked galactose, and fucose residues. To date several heterologous proteins have been expressed in L. tarentolae including both cytoplasmic enzymes and membrane receptors. Significant advances in the development of new strains and vectors, improved techniques, and the commercial availability of those tools coupled with a better understanding of the biology of Leishmania species will lead to value and power in commercial and research labs alike.
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Roberts CW, Henriquez FL. Drug target identification, validation, characterisation and exploitation for treatment of Acanthamoeba (species) infections. Exp Parasitol 2009; 126:91-6. [PMID: 20035751 DOI: 10.1016/j.exppara.2009.11.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Revised: 11/19/2009] [Accepted: 11/30/2009] [Indexed: 12/15/2022]
Abstract
New more efficacious antimicrobials as required for the treatment of Acanthamoeba infections as those currently available require arduous treatment regimes, are not always effective and are poorly active against the cystic stages. Herein, we review potential drug targets including tubulin, alternative oxidase, amino acid biosynthesis and myosin. In addition, we review the literature for current missing tools and resources for the identification, validation and development of new antimicrobials for this organism. Additional targets should come to light through a concerted genome sequencing effort.
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Affiliation(s)
- Craig W Roberts
- Strathclyde Institute for Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow G4 0NR, UK
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Madeira da Silva L, Owens KL, Murta SMF, Beverley SM. Regulated expression of the Leishmania major surface virulence factor lipophosphoglycan using conditionally destabilized fusion proteins. Proc Natl Acad Sci U S A 2009; 106:7583-8. [PMID: 19383793 PMCID: PMC2678649 DOI: 10.1073/pnas.0901698106] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Indexed: 02/07/2023] Open
Abstract
Surface glycoconjugates play important roles in the infectious cycle of Leishmania major, including the abundant lipophosphoglycan (LPG) implicated in parasite survival in the sand fly vector and the initial stages of establishment in the mammalian host macrophage. We describe a system for inducible expression of LPG, applying a novel protein-based system that allows controlled degradation of a key LPG biosynthetic enzyme, UDP-galactopyranose mutase (UGM). This methodology relies on a mutated FK506-binding protein (FKBP) destabilizing domain (dd) fused to the protein of interest; in the absence of rapamycin analogs, such as Shld1, the dd domain is destabilized, leading to proteasomal degradation, whereas drug treatment confers stabilization. Tests in L. major using dd fusions to a panel of reporters and cellular proteins confirmed its functionality, with a high degree of regulation and low background, and we established the kinetics of protein activation and/or loss. Two inexpensive and widely available ligands, FK506 and rapamycin, functioned similarly to Shld1, without effect on Leishmania growth or differentiation. We generated parasites lacking UGM through deletion of the GLF gene and substitution with a ddGLF fusion construct, either as chromosomal knockins or through episomal complementation; these showed little or no LPG expression in the absence of inducer, whereas in its presence, high levels of LPG were attained rapidly. Complement lysis tests confirmed the correct integrity of the Leishmania LPG coat. These data suggest that the dd approach has great promise in the study of LPG and other pathways relevant to parasite survival and virulence.
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Affiliation(s)
- Luciana Madeira da Silva
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Katherine L. Owens
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Silvane M. F. Murta
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Stephen M. Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
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Abstract
Genetic manipulation of single-celled organisms such as the Leishmania parasite enables in depth analysis of the consequences of genotypic change on biological function. In probing the immune responses to infection, use of transgenic Leishmania has the potential to unravel both the contribution of the parasite to the infection process and the cellular interactions and mechanisms that characterize the innate and adaptive immune responses of the host. Here, we briefly review recent technical advances in parasite genetics and explore how these methods are being used to investigate parasite virulence factors, elucidate immune regulatory mechanisms and contribute to the development of novel therapeutics for the leishmaniases. Recent developments in imaging technology, such as bioluminescence and intravital imaging, combined with parasite transfection with fluorescent or enzyme-encoding marker genes, provides a rich opportunity for novel assessment of intimate, real-time host-parasite interactions at a previously unexplored level. Further advances in transgenic technology, such as the introduction of robust inducible gene cassettes for expression in intracellular parasite stages or the development of RNA interference methods for down-regulation of parasite gene expression in the host, will further advance our ability to probe host-parasite interactions and unravel disease-promoting mechanisms in the leishmaniases.
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Affiliation(s)
- L Beattie
- Immunology and Infection Unit, Department of Biology, University of York, Hull York Medical School, Heslington, York, UK
| | - K J Evans
- Immunology and Infection Unit, Department of Biology, University of York, Hull York Medical School, Heslington, York, UK
| | - P M Kaye
- Immunology and Infection Unit, Department of Biology, University of York, Hull York Medical School, Heslington, York, UK
| | - D F Smith
- Immunology and Infection Unit, Department of Biology, University of York, Hull York Medical School, Heslington, York, UK
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Oliver BG, Silver PM, Marie C, Hoot SJ, Leyde SE, White TC. Tetracycline alters drug susceptibility in Candida albicans and other pathogenic fungi. MICROBIOLOGY (READING, ENGLAND) 2008; 154:960-970. [PMID: 18310042 PMCID: PMC2615396 DOI: 10.1099/mic.0.2007/013805-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The tetracycline (TET) promoter has been used in several systems as an inducible regulator of gene expression. In control analyses, the standard Candida albicans laboratory strain SC5314 was found to have altered susceptibility to a variety of antifungal drugs in the presence of relatively high concentrations (50-200 microg ml(-1)) of TET. Altered susceptibility was most notable with exposure to amphotericin B (AMB), with a 32-fold increase in susceptibility, and terbinafine (TRB), with a 32-fold decrease in susceptibility. The TET/AMB synergy was observed in several clinical isolates of C. albicans and in the distantly related species Aspergillus fumigatus and Cryptococcus neoformans. The TET/AMB synergy is not related to efflux pump activity, as determined by FACS analyses and by analysis of a strain containing efflux pump deletions. Gene expression analyses by luciferase and by quantitative real-time reverse transcriptase PCR failed to identify significant alterations in expression of any genes associated with resistance. C. albicans grown with TET for 48 h does show a reduction in total cellular ergosterol. Analysis of growth curves suggests that the TET effect is associated with lack of a diauxic shift, which is related to a loss of mitochondrial function. MitoTracker fluorescent dye was used to demonstrate that TET has a direct effect on mitochondrial function. These results demonstrate the need for careful analysis of TET effects when using a TET-inducible promoter, especially in studies that involve antifungal drugs. This study defines some limits to the use of the TET-inducible promoter, and identifies effects on cells that are the result of TET exposure alone, not the result of expression of a targeted gene.
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Affiliation(s)
- Brian G. Oliver
- Dept. of Pathobiology, School of Public Health and Community Medicine, University of Washington
- Seattle Biomedical Research Institute, Seattle Washington
| | - Peter M. Silver
- Dept. of Pathobiology, School of Public Health and Community Medicine, University of Washington
- Seattle Biomedical Research Institute, Seattle Washington
| | - Chelsea Marie
- Dept. of Pathobiology, School of Public Health and Community Medicine, University of Washington
- Seattle Biomedical Research Institute, Seattle Washington
| | - Samantha J. Hoot
- Dept. of Pathobiology, School of Public Health and Community Medicine, University of Washington
- Seattle Biomedical Research Institute, Seattle Washington
| | - Sarah E. Leyde
- Seattle Biomedical Research Institute, Seattle Washington
| | - Theodore C. White
- Dept. of Pathobiology, School of Public Health and Community Medicine, University of Washington
- Seattle Biomedical Research Institute, Seattle Washington
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Yao C, Luo J, Hsiao CHC, Donelson JE, Wilson ME. Leishmania chagasi: a tetracycline-inducible cell line driven by T7 RNA polymerase. Exp Parasitol 2007; 116:205-13. [PMID: 17320870 PMCID: PMC2231517 DOI: 10.1016/j.exppara.2007.01.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Revised: 12/22/2006] [Accepted: 01/02/2007] [Indexed: 11/24/2022]
Abstract
Trypanosomatid protozoa lack consensus promoters for RNA polymerase (RNAP) II. However, the artificial insertion of the T7 promoter (P(T7)) and the tetracycline repressor into Trypanosoma brucei cell lines expressing T7RNAP allows P(T7)-driven gene expression to be tetracycline-inducible. These cell lines provide a molecular tool to address protein function by several recombinant approaches. We describe here the development of an analogous Leishmania chagasi cell line bearing the genes for exogenous T7RNAP and the tetracycline repressor inserted in the multi-gene alpha-tubulin locus. A plasmid construct with P(T7) and the tetracycline operator upstream of a reporter gene, when introduced into this cell line as episomal plasmids or chromosomal insertion into the non-coding strand of an 18SrRNA gene, resulted in tetracycline-inducible expression of the reporter as much as 16- and 150-fold, respectively. The reporter was under a much tighter control when chromosomally inserted than extra-chromosomally born. Furthermore, P(T7) augmented the reporter's expression 2-fold more in comparison to P(T7)-less constructs. This cell line is the first Leishmania spp. that allows the exogenous T7RNAP-driven gene expression to be tetracycline-inducible; and may provide a useful tool for addressing protein function by manipulating expression levels of Leishmania endogenous genes.
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Affiliation(s)
- Chaoqun Yao
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA.
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Meissner M, Agop-Nersesian C, Sullivan WJ. Molecular tools for analysis of gene function in parasitic microorganisms. Appl Microbiol Biotechnol 2007; 75:963-75. [PMID: 17401559 DOI: 10.1007/s00253-007-0946-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 03/12/2007] [Accepted: 03/12/2007] [Indexed: 01/01/2023]
Abstract
With the completion of several genome sequences for parasitic protozoa, research in molecular parasitology entered the "post-genomic" era. Accompanied by global transcriptome and proteome analysis, huge datasets have been generated that have added many novel candidates to the list of drug and vaccine targets. The challenge is now to validate these factors and to bring science back to the bench to perform a detailed characterization. In some parasites, like Trypanosoma brucei, high-throughput genetic screens have been established using RNA interference [for a detailed review, see Motyka and Englund (2004)]. In most protozoan parasites, however, more time-consuming approaches have to be employed to identify and characterize the function of promising candidates in detail. This review aims to summarize the status of molecular genetic tools available for a variety of protozoan pathogens and discuss how they can be implemented to advance our understanding of parasite biology.
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Affiliation(s)
- Markus Meissner
- Hygieneinstitut, Abteilung Parasitologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany.
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Taylor MC, Kelly JM. pTcINDEX: a stable tetracycline-regulated expression vector for Trypanosoma cruzi. BMC Biotechnol 2006; 6:32. [PMID: 16824206 PMCID: PMC1544328 DOI: 10.1186/1472-6750-6-32] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Accepted: 07/06/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Trypanosoma cruzi is a protozoan pathogen of major medical importance in Latin America. It is also an early diverging eukaryote that displays many unusual biochemical features. The completion of the T. cruzi genome project has highlighted the need to extend the range of techniques available to study gene function. To this end we report the development of a stable tetracycline-dependent expression vector applicable to this parasite and describe in detail the parameters of the system. RESULTS We first produced T. cruzi cell lines that constitutively expressed bacteriophage T7 RNA polymerase and the tetracycline repressor protein from a multicopy episome. An integrative vector with an inducible expression site under the control of a tetracycline-regulatable T7 promoter (pTcINDEX) was targeted to the transcriptionally silent ribosomal RNA spacer region of these parasites and transformants selected using a T7 RNA polymerase-dependent hygromycin resistance gene. To test the system we used two marker proteins, luciferase and red fluorescent protein (RFP), and an endogenous parasite protein (a mitochondrial superoxide dismutase). In each case we found that induction was both time and dose-dependent. Luciferase mRNA could be induced by at least 100-fold, and luciferase activity up to 60-fold, within 24 hours of the addition of tetracycline. When we examined RFP induction by confocal microscopy and fluorescence activated cell sorter, we observed very high levels of expression (>1000-fold increase in fluorescence intensity), although this was not synchronous throughout clonal populations. Induction of superoxide dismutase resulted in an 18-fold increase in cellular activity. The observation that a tagged version of the enzyme was correctly targeted to the mitochondrion demonstrates that our expression system may also provide a high-throughput strategy for subcellular localisation. CONCLUSION Our results show that pTcINDEX represents a valuable addition to the genetic tools available for T. cruzi. The vector system is sufficiently flexible that it should have widespread uses including inducible expression of tagged proteins, generation of conditional knockout cell lines and the application of dominant-negative approaches.
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Affiliation(s)
- Martin C Taylor
- London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - John M Kelly
- London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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Holzmuller P, Hide M, Sereno D, Lemesre JL. Leishmania infantum amastigotes resistant to nitric oxide cytotoxicity: Impact on in vitro parasite developmental cycle and metabolic enzyme activities. INFECTION GENETICS AND EVOLUTION 2006; 6:187-97. [PMID: 15905133 DOI: 10.1016/j.meegid.2005.03.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2005] [Revised: 03/22/2005] [Accepted: 03/22/2005] [Indexed: 10/25/2022]
Abstract
Nitric oxide (NO) has been demonstrated to be the principal effector molecule mediating intracellular killing of Leishmania. The free radical characteristic of NO prevented direct induction of resistance in Leishmania wild-type parasites. Starting from the previous observation that antimony-resistant amastigotes of Leishmania infantum were not affected by NO-induced apoptotic death, we used a continuous NO pressure protocol and succeeded in inducing NO resistance in amastigote forms of L. infantum. Two clones resistant to 50 microM (LiNOR50) and 100 microM (LiNOR100) of the NO donor DETA/NONOate, derived from parental clone weakly resistant to trivalent antimony (LiSbIIIR4), were selected and analysed. Both clones were also resistant to other NO donors, particularly SNAP. In the absence of potassium antimonyl tartrate, all clones (LiSbIIIR4, LiNOR50 and LiNOR100) lost their antimony resistance almost totally. Interestingly, the parasitic developmental life cycle of NO-resistant mutants was dramatically disturbed. NO-resistant amastigotes differentiated more rapidly into promastigotes than the wild-type ones. Nevertheless, NO-resistant amastigotes produce a maximal number of parasites 1.5-2 times lower than the wild-type whereas, after differentiation, NO-resistant promastigotes produced more cells than the wild-type. We showed that this last phenomenon could be a consequence of the overexpression of parasitic enzymes involved in both glycolysis and respiration processes. NO-resistant amastigotes overexpressed three enzymes: cis-aconitase, glyceraldehyde-3-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. The two first enzymes are NO molecular targets which could be directly involved in NO resistance and the third one could interfere in modifying Leishmania metabolism.
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Affiliation(s)
- Philippe Holzmuller
- UR 008 Pathogénie des Trypanosomatidés, IRD (Institut de Recherche pour le Développement), B.P. 64501, 911 avenue Agropolis, 34394 Montpellier cedex 5, France.
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22
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van Poppel NFJ, Welagen J, Duisters RFJJ, Vermeulen AN, Schaap D. Tight control of transcription in Toxoplasma gondii using an alternative tet repressor. Int J Parasitol 2006; 36:443-52. [PMID: 16516216 DOI: 10.1016/j.ijpara.2006.01.005] [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] [Received: 11/08/2005] [Revised: 12/28/2005] [Accepted: 01/05/2006] [Indexed: 11/24/2022]
Abstract
Fusion of yellow fluorescent protein (YFP) to the N-terminus of the Escherichia coli Tn10 tet repressor (TetR) created a functional YFP-TetR repressor with the capacity of 88-fold repression of transcription when expressed in Toxoplasma gondii. As a test promoter we used the T. gondii ribosomal protein RPS13 promoter for which we provide experimental evidence of having a single major transcriptional start site, a condition favourable to the design of inducible expression systems. Integration of four tet operator (tetO) elements, 23-43 bp upstream of the RPS13 transcriptional start site, resulted in maximal repression of transcription (88-fold). Moreover, integration of these four tetO elements reduced the promoter activity only 20% in comparison with the wildtype promoter. Regulation was six-fold higher compared with an inducible expression system employing wildtype TetR. Importantly, only 0.1 microg/ml tetracycline was required for maximal induction demonstrating a higher affinity of tetracycline for YFP-TetR than for wildtype TetR which required 1 microg/ml tetracycline for maximal induction. The use of 0.1 microg/ml tetracycline allows prolonged continuous culturing of T. gondii for which levels of 1 microg/ml tetracycline are toxic. Our results show that YFP-TetR is superior to TetR for transcriptional regulation in T. gondii and we expect that its improved characteristics will be exploitable in other parasites or higher eukaryotes.
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Affiliation(s)
- Nicole F J van Poppel
- Department of Parasitology R and D, Intervet International BV, P.O. Box 31, 5830 AA Boxmeer, The Netherlands.
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23
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Alsford S, Kawahara T, Glover L, Horn D. Tagging a T. brucei RRNA locus improves stable transfection efficiency and circumvents inducible expression position effects. Mol Biochem Parasitol 2005; 144:142-8. [PMID: 16182389 PMCID: PMC3833055 DOI: 10.1016/j.molbiopara.2005.08.009] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 08/09/2005] [Accepted: 08/11/2005] [Indexed: 11/20/2022]
Abstract
In Trypanosoma brucei, RNA interference (RNAi) and recombinant protein expression are established as powerful approaches for functional genomics, particularly when combined with inducible expression. The favoured methods involve exploiting homologous recombination to target expression cassettes to a chromosome sub-set to establish stable cell lines. Unfortunately, bloodstream-form cells, those that cause disease in mammals, exhibit low efficiency stable transfection. Current expression systems can also exhibit other undesirable features, including variable position effects and leaky, inducible expression. We have developed systems in bloodstream-form cells that alleviate these problems. Using constructs for RNAi and expression of (GFP) tagged proteins, we target a (hyg) tagged ribosomal RNA (RRNA) locus which circumvents position effects and allows increased targeting efficiency. We also report a compatible double-inducible system for tight regulation of highly toxic products. This system exploits a new inducible RRNA promoter to drive T7 RNA polymerase (T7RNAP) transcription which then drives expression from inducible T7 promoters. The developments described should facilitate functional analysis and increased throughput.
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Affiliation(s)
- Sam Alsford
- London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT. UK
| | - Taemi Kawahara
- London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT. UK
| | - Lucy Glover
- London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT. UK
| | - David Horn
- London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT. UK
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Kushnir S, Gase K, Breitling R, Alexandrov K. Development of an inducible protein expression system based on the protozoan host Leishmania tarentolae. Protein Expr Purif 2005; 42:37-46. [PMID: 15939291 DOI: 10.1016/j.pep.2005.03.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 02/27/2005] [Accepted: 03/02/2005] [Indexed: 11/23/2022]
Abstract
Production of functional eukaryotic proteins in recombinant form is a bottle-neck in various post-genomic applications and in life science in general. At least partially this is due to the problems associated with the use of endogenous RNA polymerase II for high-level transcription of heterologous genes in eukaryotic expression systems. To circumvent these problems we developed a new inducible protein expression system based on the protozoan host Leishmania tarentolae (Trypanosomatidae). We have created a strain of L. tarentolae constitutively co-expressing T7 RNA polymerase and tetracycline repressor. This strain could be stably transformed with the heterologous target gene under control of the T7 promoter/TET operator assembly, which can initiate transcription upon addition of tetracycline to the culture medium. Using this system, we demonstrated that enhanced green fluorescent protein (EGFP) could be overexpressed to a level of ca. 1% of total cellular protein. The developed system was tested for its ability to inducibly co-express multiple genes. Using two copies of the egfp gene integrated at two different genomic sites, we could obtain expression levels reaching 4% of total cellular protein. Further possible improvements and applications of the developed system are discussed.
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Affiliation(s)
- Susanna Kushnir
- Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, Dortmund, Germany
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25
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Meissner M, Soldati D. The transcription machinery and the molecular toolbox to control gene expression in Toxoplasma gondii and other protozoan parasites. Microbes Infect 2005; 7:1376-84. [PMID: 16087378 DOI: 10.1016/j.micinf.2005.04.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 04/28/2005] [Accepted: 04/29/2005] [Indexed: 02/06/2023]
Abstract
The phylum of Apicomplexa groups a large variety of obligate intracellular protozoan parasites that exhibit complicated life cycles, involving transmission and differentiation within and between different hosts. Little is known about the level of regulation and the nature of the factors controlling gene expression throughout their life stages. Unravelling the mechanisms that govern gene regulation is critical for the development of adequate tools to manipulate these parasites and modulate gene expression, in order to study their function in molecular terms in vivo. A comparative analysis of the transcriptional machinery of several apicomplexan genomes and other protozoan parasites has revealed the existence of a primitive eukaryotic transcription apparatus consisting only of a subset of the general transcription factors found in higher eukaryotes. These findings have some direct implications on development of tools.
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Affiliation(s)
- Markus Meissner
- Hygieneinstitut, abteilung parasitologie, universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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Abstract
Gene regulation by tetracyclines has become a widely-used tool to study gene functions in pro- and eukaryotes. This regulatory system originates from Gram-negative bacteria, in which it fine-tunes expression of a tetracycline-specific export protein mediating resistance against this antibiotic. This review attempts to describe briefly the selective pressures governing the evolution of tetracycline regulation, which have led to the unique regulatory properties underlying its success in manifold applications. After discussing the basic mechanisms we will present the large variety of designed alterations of activities which have contributed to the still growing tool-box of components available for adjusting the regulatory properties to study gene functions in different organisms or tissues. Finally, we provide an overview of the various experimental setups available for pro- and eukaryotes, and touch upon some highlights discovered by the use of tetracycline-dependent gene regulation.
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Affiliation(s)
- Christian Berens
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Staudtstr. 5, D-91058, Erlangen, Germany
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Berens C, Hillen W. Gene regulation by tetracyclines. Constraints of resistance regulation in bacteria shape TetR for application in eukaryotes. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:3109-21. [PMID: 12869186 DOI: 10.1046/j.1432-1033.2003.03694.x] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Tet repressor protein (TetR) regulates transcription of a family of tetracycline (tc) resistance determinants in Gram-negative bacteria. The resistance protein TetA, a membrane-spanning H+-[tc.M]+ antiporter, must be sensitively regulated because its expression is harmful in the absence of tc, yet it has to be expressed before the drugs' concentration reaches cytoplasmic levels inhibitory for protein synthesis. Consequently, TetR shows highly specific tetO binding to reduce basal expression and high affinity to tc to ensure sensitive induction. Tc can cross biological membranes by diffusion enabling this inducer to penetrate the majority of cells. These regulatory and pharmacological properties are the basis for application of TetR to selectively control the expression of single genes in lower and higher eukaryotes. TetR can be used for that purpose in some organisms without further modifications. In mammals and in a large variety of other organisms, however, eukaryotic transcriptional activator or repressor domains are fused to TetR to turn it into an efficient regulator. Mechanistic understanding and the ability to engineer and screen for mutants with specific properties allow tailoring of the DNA recognition specificity, the response to inducer tc and the dimerization specificity of TetR-based eukaryotic regulators. This review provides an overview of the TetR properties as they evolved in bacteria, the functional modifications necessary to transform it into a convenient, specific and efficient regulator for use in eukaryotes and how the interplay between structure--function studies in bacteria and specific requirements of particular applications in eukaryotes have made it a versatile and highly adaptable regulatory system.
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Affiliation(s)
- Christian Berens
- Lehrstuhl für Mikrobiologie, Institut für Mikrobiologie, Biochemie und Genetik, Friedrich-Alexander Universität Erlangen-Nürnberg, Germany
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28
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Abstract
Transient and stable gene delivery systems are available for Trichomonas vaginalis, however, they do not allow regulated expression of target genes. To study essential genes or proteins that are toxic to the cells when over expressed, we have developed an inducible/repressible gene expression system in this parasite, which is driven by the tet-operator (tetO) and regulated tetracycline-responsive Tet repressor (TetR). Inducible chloramphenicol acetyl transferase (CAT) gene expression is observed using a concentration of tetracycline (Tc) as low as 0.1 microg x ml(-1). Expression increases with drug dose with a maximum level of CAT induction achieved in stable transfectants using 5 microg x ml(-1) Tc. CAT protein expression is detectable within 12 h and reaches a maximum level at 48 h, demonstrating that inducible expression is time and dose-dependent. In an inverse experiment, parasites previously cultivated with 1 microg x ml(-1) of Tc for 48 h, were grown in the absence of drug to determine the kinetics of repression. A significant decrease in protein concentration is detected after 48 h, and no detectable protein is observed after 72 h. Experiments replacing the CAT gene with the puromycin N-acetyltransferase (PAC) gene in the Tet regulated expression construct have demonstrated the use of this system for testing putative toxic and essential genes. The establishment of regulated gene expression of exogenous genes in T. vaginalis represents a crucial step towards determining the function of proteins in this divergent parasite.
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Affiliation(s)
- Diana Ortiz
- Department of Microbiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Breitling R, Klingner S, Callewaert N, Pietrucha R, Geyer A, Ehrlich G, Hartung R, Müller A, Contreras R, Beverley SM, Alexandrov K. Non-pathogenic trypanosomatid protozoa as a platform for protein research and production. Protein Expr Purif 2002; 25:209-18. [PMID: 12135552 DOI: 10.1016/s1046-5928(02)00001-3] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
All currently existing eukaryotic protein expression systems are based on autonomous life forms. To exploit the potential practical benefits associated with parasitic organisms we have developed a new protein expression system based on Leishmania tarentolae (Trypanosomatidae), a protozoan parasite of lizards. To achieve strong transcription, the genes of interest were integrated into the small subunit ribosomal RNA gene. Expression levels obtained were up to 30 mg of recombinant protein per liter of suspension culture and increased linearly with the number of integrated gene copies. To assess the system's potential for production of post-translationally modified proteins, we have expressed human erythropoietin in L. tarentolae. The recombinant protein isolated from the culture supernatants was biologically active, natively processed at the N-terminus, and N-glycosylated. The N-glycosylation was exceptionally homogeneous, with a mammalian-type biantennary oligosaccharide and the Man(3)GlcNAc(2) core structure accounting for >90% of the glycans present. L. tarentolae is thus the first described biotechnologically useful unicellular eukaryotic organism producing biantennary fully galactosylated, core-alpha-1,6-fucosylated N-glycans.
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Chang KP, McGwire BS. Molecular determinants and regulation of Leishmania virulence. KINETOPLASTID BIOLOGY AND DISEASE 2002; 1:1. [PMID: 12234388 PMCID: PMC119322 DOI: 10.1186/1475-9292-1-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2002] [Accepted: 05/20/2002] [Indexed: 11/10/2022]
Abstract
A Leishmania model to explain microbial virulence in chronic infectious diseases is proposed. All these diseases progress from infection to symptomatic phase to host death or recovery. The outcome of each phase is depicted to result from the interactions of a distinct group of parasite molecules with a specific host immune compartment. The first group consists of invasive/evasive determinants, which are largely parasite cell surface and secreted molecules. Their activities help parasites establish infection by overcoming host immunologic and non-immunologic barriers. These determinants do not cause disease per se, but are indispensable for infection necessary for the development of a disease-state. The second group of parasite molecules consists of "pathoantigenic" determinants - unique parasite epitopes present often within otherwise highly conserved cytoplasmic molecules. Immune response against these determinants is thought to result in immunopathology manifested as clinical signs or symptoms, namely the virulent phenotype. The third group of parasite molecules is hypothetically perceived as vaccine determinants. Their interactions with the host immune system lead to the elimination or reduction of parasites to effect a clinical cure. Differential expression of these determinants alone by parasites may alter their interactions with the hosts. Virulent phenotype is consequently presented as a spectrum of manifestations from asymptomatic infection to fatality. A secondary level of regulation lies in host genetic and environmental factors. The model suggests that different parasite determinants may be targeted by different strategies to achieve more effective control of leishmaniasis and other similar diseases.
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Affiliation(s)
- Kwang-Poo Chang
- Department of Microbiology/Immunology, University of Health Sciences/Chicago Medical School, North Chicago, IL. USA
| | - Bradford S McGwire
- Department of Pathology, The Feinberg School of Medicine, Northwestern University and Section of Infectious Diseases, College of Medicine, University of Illinois-Chicago, Chicago, IL. USA
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Hatabu T, Matsumoto Y, Kawazu SI, Nakamura Y, Kamio T, Lu HG, Chang KP, Hashiguchi Y, Kano S, Onodera T, Matsumoto Y. The expression system of biologically active canine interleukin-8 in Leishmania promastigotes. Parasitol Int 2002; 51:63-71. [PMID: 11880228 DOI: 10.1016/s1383-5769(01)00107-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
It has been reported that Leishmania promastigotes have ability to express foreign genes on drug selectable plasmids. To investigate further abilities of the recently described expression vector, P6.5, in the transfection of Leishmania organisms (Chen D-Q, Kolli BK, Yadava N et al. Episomal expression of specific sense and antisense mRNAs in Leishmania amazonensis: modulation of gp63 levels in promastigotes and their infection of macrophages in vitro. Infect Immun 2000;68:80--86), the constructed expression vector, which contains canine interleukin-8 (cIL-8) coding cDNA, was introduced by electroporation to promastigotes of four species of the genus Leishmania: Leishmania amazonensis, L. equatorensis, L. donovani and L. infantum. Extrachromosomal DNAs and total RNAs from the transfected promastigotes were subjected to polymerase chain reaction (PCR) and reverse transcriptase-PCR, respectively, using cIL-8 gene specific primers, and a predicted product of 330 bp was detected. Western blot analysis using a mouse monoclonal antibody raised against cIL-8 demonstrated the successful expression of cIL-8 in the transfectants and culture supernatants. Culture supernatants of the transfected L. amazonensis and L. equatorensis promastigotes showed a high chemotactic activity to both dog and mouse polymorphonuclear leukocytes. These results indicate that Leishmania promastigotes transfected with the expression vector P6.5 containing cIL-8 cDNA are capable of producing biologically active cIL-8. The Leishmania expression system using the P6.5 vector might be a useful alternative for the production of biologically active recombinant cytokines.
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Affiliation(s)
- Toshimitsu Hatabu
- Department of Molecular Immunology, School of Agriculture and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Yan S, Martinez-Calvillo S, Schnaufer A, Sunkin S, Myler PJ, Stuart K. A low-background inducible promoter system in Leishmania donovani. Mol Biochem Parasitol 2002; 119:217-23. [PMID: 11814573 DOI: 10.1016/s0166-6851(01)00418-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We report here a second-generation tetracycline-responsive repressor-operator system in Leishmania donovani. In this system, expression of a reporter luciferase gene (LUC) is driven by the inducible Leishmania ribosomal RNA promoter on the DNA strand opposite to a hygromycin resistance gene (HYG) whose expression is driven by the endogenous pol I promoter on chromosome 27 (rDNA locus) or the endogenous pol II promoter on chromosome 35 (LD1 locus). Transgenic cell lines showed regulation of LUC gene expression over three orders of magnitude. In the absence of tetracycline, luciferase expression levels were 2-3-fold higher than machine background when integrated into the LD1 locus, but was over 10-fold higher than machine background when integrated into the rDNA locus.
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Affiliation(s)
- Shaofeng Yan
- Seattle Biomedical Research Institute, 4 Nickerson Street, Seattle, WA 98109-1651, USA
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Martínez-Calvillo S, Sunkin SM, Yan S, Fox M, Stuart K, Myler PJ. Genomic organization and functional characterization of the Leishmania major Friedlin ribosomal RNA gene locus. Mol Biochem Parasitol 2001; 116:147-57. [PMID: 11522348 DOI: 10.1016/s0166-6851(01)00310-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The sequence and gene organization of the ribosomal RNA (rRNA) genes of Leishmania major Friedlin (LmjF) were determined. Interestingly, the rDNA repeat unit contained a duplicated 526 bp fragment at the 3' end of the unit with two copies of the LSUepsilon rRNA gene. Our results suggested the presence of only approximately 24 copies of the rRNA unit per diploid genome in LmjF. Repetitive elements (IGSRE) of 63 bp occurred in the intergenic spacer (IGS) between the LSUepsilon and the SSU rRNA genes. Among the different rDNA units, the region containing the IGSRE fluctuated in length from approximately 1.3 to approximately 18 kb. The transcription initiation site (TIS) of the rRNA unit was localized by primer extension to 1043 bp upstream of the SSU gene and 184 bp downstream of the IGSRE. Sequence comparison among several species of Leishmania showed a high degree of conservation around the TIS. Moreover, the IGSRE also showed considerable similarity between Leishmania species. In transient transfection assays, a fragment containing the TIS directed a 164- to 178-fold increase in luciferase activity over the no-insert control, indicating the presence of a promoter within this 391 bp fragment. The LmjF promoter region was also functional in other species of Leishmania. Nuclear run-on analyses demonstrated that only the rRNA-coding strand is transcribed, downstream of this RNA polymerase I (pol I) promoter. These experiments also suggested that transcription terminates upstream of the IGSRE.
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Affiliation(s)
- S Martínez-Calvillo
- Seattle Biomedical Research Institute, 4 Nickerson Street, Seattle, WA 98109-1651, USA
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