scholarly journals Leishmania donovani Polyamine Biosynthetic Enzyme Overproducers as Tools To Investigate the Mode of Action of Cytotoxic Polyamine Analogs

2007 ◽  
Vol 51 (2) ◽  
pp. 438-445 ◽  
Author(s):  
Sigrid C. Roberts ◽  
Yuqui Jiang ◽  
Judith Gasteier ◽  
Benjamin Frydman ◽  
Laurence J. Marton ◽  
...  
Keyword(s):  
Mode Of Action ◽  
Biosynthetic Pathway ◽  
Leishmania Donovani ◽  
Target Genes ◽  
Protozoan Parasite ◽  
Biosynthetic Enzymes ◽  
General Strategy ◽  
Biosynthetic Enzyme ◽  
High Level ◽  
Polyamine Analogs

ABSTRACT A number of anticancer and antiparasitic drugs are postulated to target the polyamine biosynthetic pathway and polyamine function, but the exact mode of action of these compounds is still being elucidated. To establish whether polyamine analogs specifically target enzymes of the polyamine pathway, a model was developed using strains of the protozoan parasite Leishmania donovani that overproduce each of the polyamine biosynthetic enzymes. Promastigotes overexpressing episomal constructs encoding ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (ADOMETDC), or spermidine synthase (SPDSYN) revealed robust overproduction of the corresponding polyamine biosynthetic enzyme. Polyamine pools, however, were either unchanged or only marginally affected, implying that regulatory mechanisms must exist. The ODC, ADOMETDC, and SPDSYN overproducer strains exhibited a high level of resistance to difluoromethylornithine, 5′-{[(Z)-4-amino-2-butenyl]methylamino}-5′-deoxyadenosine, and n-butylamine, respectively, confirming previous observations that these agents specifically target polyamine enzymes. Conversely, augmented levels of polyamine biosynthetic enzymes did not affect the sensitivity of L. donovani promastigotes to pentamidine, berenil, and mitoguazone, drugs that were postulated to target the polyamine pathway, implying alternative and/or additional targets for these agents. The sensitivities of wild-type and overproducing parasites to a variety of polyamine analogs were also tested. The polyamine enzyme-overproducing lines offer a rapid cell-based screen for assessing whether synthetic polyamine analogs exert their mechanism of action predominantly on the polyamine biosynthetic pathway in L. donovani. Furthermore, the drug resistance engendered by the amplification of target genes and the overproduction of the encoded protein offers a general strategy for evaluating and developing therapeutic agents that target specific proteins in Leishmania.

Natural and synthetic indirubins as potent and selective inhibitors of the protozoan parasite Leishmania donovani

Planta Medica ◽  
2007 ◽  
Vol 73 (09) ◽  
Author(s):  
E Xingi ◽  
D Smirlis ◽  
S Bisti ◽  
V Myrianthopoulos ◽  
P Magiatis ◽  
...  
Keyword(s):  
Leishmania Donovani ◽  
Protozoan Parasite ◽  
Selective Inhibitors ◽  
Parasite Leishmania ◽  
Natural And Synthetic

Diagnosis and Causative Species of Visceral Leishmaniasis in Southwest Saudi Arabia

2021 ◽  
Author(s):  
Aymen Abdelhaleem ◽  
Nabil Dhayhi ◽  
Mohamed Salih Mahfouz ◽  
Ommer Daffalla ◽  
Mansour Mubarki ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Visceral Leishmaniasis ◽  
Real Time ◽  
Real Time Pcr ◽  
Leishmania Donovani ◽  
Target Genes ◽  
Sample Volume ◽  
Pcr Products ◽  
Polymerase Chain ◽  
Robust Evidence

Visceral leishmaniasis (VL) is the most severe clinical form of the disease and has been reported in the Jazan region of southwest Saudi Arabia. This study aimed to diagnose VL by real-time polymerase chain reaction (PCR) and the direct agglutination test (DAT) and to identify the causative Leishmania species. A total of 80 participants, including 30 suspected VL patients, 30 healthy endemic control individuals, and 20 malaria disease controls, were enrolled in this study. Blood samples were collected and tested for Leishmania DNA by real-time PCR and for antibody by the DAT. Sequencing of some amplified PCR products was used to identify the causative Leishmania species. The diagnosis of VL was successfully achieved by both real-time PCR and by DAT with 100% sensitivity. Leishmania donovani and Leishmania infantum species were detected by sequencing both by the kDNA and ITS1 target genes, followed a BLASTn search. The detection of VL antibody by the DAT followed by the confirmatory detection of Leishmania DNA in patient blood by PCR could promote the adoption of the much less invasive and more sensitive methods for the routine diagnosis of VL. Further study with high sample volume to evaluate the PCR and the DAT are needed, to generate more robust evidence. Based on the sequencing results, emerging studies on VL should focus on the causative Leishmania species, reservoirs, and vectors that are important in the study area.

Developmental gene expression in Leishmania donovani: differential cloning and analysis of an amastigote-stage-specific gene

1994 ◽  
Vol 14 (5) ◽  
pp. 2975-2984
Author(s):  
H Charest ◽  
G Matlashewski
Keyword(s):  
Life Cycle ◽  
Leishmania Donovani ◽  
Repetitive Sequences ◽  
Protozoan Parasite ◽  
Life Cycle Stage ◽  
Immune Serum ◽  
Sand Fly ◽  
Specific Gene ◽  
Reading Frame ◽  
Developmental Gene Expression

Leishmania protozoans are the causative agents of leishmaniasis, a major parasitic disease in humans. During their life cycle, Leishmania protozoans exist as flagellated promastigotes in the sand fly vector and as nonmotile amastigotes in the mammalian hosts. The promastigote-to-amastigote transformation occurs in the phagolysosomal compartment of the macrophage cell and is a critical step for the establishment of the infection. To study this cytodifferentiation process, we differentially screened an amastigote cDNA library with life cycle stage-specific cDNA probes and isolated seven cDNAs representing amastigote-specific transcripts. Five of these were closely related (A2 series) and recognized, by Northern (RNA) blot analyses, a 3.5-kb transcript in amastigotes and in amastigote-infected macrophages. Expression of the amastigote-specific A2 gene was induced in promastigotes when they were transferred from culture medium at 26 degrees C and pH 7.4 to medium at 37 degrees C and pH 4.5, conditions which mimic the macrophage phagolysosomal environment. A2 genes are clustered in tandem arrays, and a 6-kb fragment corresponding to a unit of the cluster was cloned and partially sequenced. An open reading frame found within the A2-transcribed region potentially encoded a 22-kDa protein containing repetitive sequences. The recombinant A2 protein produced in Escherichia coli cells was specifically recognized by immune serum from a patient with visceral leishmaniasis. The A2 protein repetitive element has strong homology with an S antigen of Plasmodium falciparum, the protozoan parasite responsible for malaria. Both the A2 protein of Leishmania donovani and the S antigen of P. falciparum are stage specific and developmentally expressed in mammalian hosts.

Insights into Enhancer RNAs: Biogenesis and Emerging Role in Brain Diseases

2021 ◽  
pp. 107385842110468
Author(s):  
Yuxin Shen ◽  
Zhengyi Huang ◽  
Ruiqing Yang ◽  
Yunlong Chen ◽  
Qiang Wang ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Small Proportion ◽  
Target Genes ◽  
Noncoding Rnas ◽  
Histone Mark ◽  
Brain Diseases ◽  
Enhancer Activity ◽  
Cis Acting ◽  
High Level ◽  
Classification Function

Enhancers are cis-acting elements that control the transcription of target genes and are transcribed into a class of noncoding RNAs (ncRNAs) termed enhancer RNAs (eRNAs). eRNAs have shorter half-lives than mRNAs and long noncoding RNAs; however, the frequency of transcription of eRNAs is close to that of mRNAs. eRNA expression is associated with a high level of histone mark H3K27ac and a low level of H3K27me3. Although eRNAs only account for a small proportion of ncRNAs, their functions are important. eRNAs can not only increase enhancer activity by promoting the formation of enhancer-promoter loops but also regulate transcriptional activation. Increasing numbers of studies have found that eRNAs play an important role in the occurrence and development of brain diseases; however, further research into eRNAs is required. This review discusses the concept, characteristics, classification, function, and potential roles of eRNAs in brain diseases.

scholarly journals Genetic Validation of Leishmania donovani Lysyl-tRNA Synthetase Shows that It Is Indispensable for Parasite Growth and Infectivity

mSphere ◽  
2017 ◽  
Vol 2 (4) ◽  
Author(s):  
Sanya Chadha ◽  
N. Arjunreddy Mallampudi ◽  
Debendra K. Mohapatra ◽  
Rentala Madhubala
Keyword(s):  
Visceral Leishmaniasis ◽  
Leishmania Donovani ◽  
Essential Gene ◽  
Protozoan Parasite ◽  
Protein Translation ◽  
Trna Synthetase ◽  
Parasite Growth ◽  
Coding Sequences ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases

ABSTRACT Leishmania donovani is a protozoan parasite that causes visceral leishmaniasis. Increasing resistance and severe side effects of existing drugs have led to the need to identify new chemotherapeutic targets. Aminoacyl-tRNA synthetases (aaRSs) are ubiquitous and are required for protein synthesis. aaRSs are known drug targets for bacterial and fungal pathogens. Here, we have characterized and evaluated the essentiality of L. donovani lysyl-tRNA synthetase (LdLysRS). Two different coding sequences for lysyl-tRNA synthetases are annotated in the Leishmania genome database. LdLysRS-1 (LdBPK_150270.1), located on chromosome 15, is closer to apicomplexans and eukaryotes, whereas LdLysRS-2 (LdBPK_300130.1), present on chromosome 30, is closer to bacteria. In the present study, we have characterized LdLysRS-1. Recombinant LdLysRS-1 displayed aminoacylation activity, and the protein localized to the cytosol. The LdLysRS-1 heterozygous mutants had a restrictive growth phenotype and attenuated infectivity. LdLysRS-1 appears to be an essential gene, as a chromosomal knockout of LdLysRS-1 could be generated when the gene was provided on a rescuing plasmid. Cladosporin, a fungal secondary metabolite and a known inhibitor of LysRS, was more potent against promastigotes (50% inhibitory concentration [IC50], 4.19 µM) and intracellular amastigotes (IC50, 1.09 µM) than were isomers of cladosporin (3-epi-isocladosporin and isocladosporin). These compounds exhibited low toxicity to mammalian cells. The specificity of inhibition of parasite growth caused by these inhibitors was further assessed using LdLysRS-1 heterozygous mutant strains and rescue mutant promastigotes. These inhibitors inhibited the aminoacylation activity of recombinant LdLysRS. Our data provide a framework for the development of a new class of drugs against this parasite. IMPORTANCE Aminoacyl-tRNA synthetases are housekeeping enzymes essential for protein translation, providing charged tRNAs for the proper construction of peptide chains. These enzymes provide raw materials for protein translation and also ensure fidelity of translation. L. donovani is a protozoan parasite that causes visceral leishmaniasis. It is a continuously proliferating parasite that depends heavily on efficient protein translation. Lysyl-tRNA synthetase is one of the aaRSs which charges lysine to its cognate tRNA. Two different coding sequences for lysyl-tRNA synthetases (LdLysRS) are present in this parasite. LdLysRS-1 is closer to apicomplexans and eukaryotes, whereas LdLysRS-2 is closer to bacteria. Here, we have characterized LdLysRS-1 of L. donovani. LdLysRS-1 appears to be an essential gene, as the chromosomal null mutants did not survive. The heterozygous mutants showed slower growth kinetics and exhibited attenuated virulence. This study also provides a platform to explore LdLysRS-1 as a potential drug target.

scholarly journals Role of cAMP Signaling in the Survival and Infectivity of the Protozoan Parasite, Leishmania donovani

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Arunima Biswas ◽  
Arijit Bhattacharya ◽  
Pijush K. Das
Keyword(s):  
Leishmania Donovani ◽  
Protozoan Parasite ◽  
Camp Level ◽  
Camp Signaling ◽  
Regulatory Subunit ◽  
Developmentally Regulated ◽  
Camp Phosphodiesterase ◽  
Environmental Trigger ◽  
Dependent Protein ◽  
Camp Metabolism

Leishmania donovani, while invading macrophages, encounters striking shift in temperature and pH (from 22°C and pH 7.2 to 37°C and pH 5.5), which act as the key environmental trigger for differentiation, and increases cAMP level and cAMP-mediated responses. For comprehensive understanding of cAMP signaling, we studied the enzymes related to cAMP metabolism. A stage-specific and developmentally regulated isoform of receptor adenylate cyclase (LdRACA) showed to regulate differentiation-coupled induction of cAMP. The soluble acidocalcisomal pyrophosphatase, Ldvsp1, was the major isoform regulating cAMP level in association with LdRACA. A differentially expressed soluble cytosolic cAMP phosphodiesterase (LdPDEA) might be related to infection establishment by shifting trypanothione pool utilization bias toward antioxidant defense. We identified and cloned a functional cAMP-binding effector molecule from L. donovani (a regulatory subunit of cAMP-dependent protein kinase, LdPKAR) that may modulate metacyclogenesis through induction of autophagy. This study reveals the significance of cAMP signaling in parasite survival and infectivity.

scholarly journals Absence of Cyanotoxins in Llayta, Edible Nostocaceae Colonies from the Andes Highlands

Toxins ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 382 ◽  
Author(s):  
Alexandra Galetović ◽  
Joana Azevedo ◽  
Raquel Castelo-Branco ◽  
Flavio Oliveira ◽  
Benito Gómez-Silva ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Target Genes ◽  
Food Ingredient ◽  
Chemical Methods ◽  
The Andes ◽  
Mcye Gene ◽  
Safe Food

Edible Llayta are cyanobacterial colonies consumed in the Andes highlands. Llayta and four isolated cyanobacteria strains were tested for cyanotoxins (microcystin, nodularin, cylindrospermopsin, saxitoxin and β-N-methylamino-L-alanine—BMAA) using molecular and chemical methods. All isolates were free of target genes involved in toxin biosynthesis. Only DNA from Llayta amplified the mcyE gene. Presence of microcystin-LR and BMAA in Llayta extracts was discarded by LC/MS analyses. The analysed Llayta colonies have an incomplete microcystin biosynthetic pathway and are a safe food ingredient.

Ambiguous skin ulcer on the ear pinna

2019 ◽  
Vol 49 (2) ◽  
pp. 141-143
Author(s):  
Nazar Abdalla
Keyword(s):  
Saudi Arabia ◽  
Leishmania Donovani ◽  
Protozoan Parasite ◽  
Isozyme Pattern ◽  
Parasitic Disease ◽  
Animal Reservoir ◽  
Kala Azar ◽  
Biphasic Life Cycle ◽  
Human Leishmaniasis ◽  
Cutaneous Form

Cutaneous leishmaniasis (CL) is a parasitic disease which has a biphasic life cycle; infection by promastigotes from the sandfly reaches a wound where it is phagocytosed by macrophages, producing the amastigote (the Leishmania donovani body) in the host. A protozoan parasite transmitted by the phlebotomous sandfly causes human leishmaniasis. Cutaneous forms include classical cutaneous, mucocutaneous and post-kala-azar dermal leishmaniasis. It affects c. 300 million individuals in more than 90 nations around the globe. The cutaneous form in the Old World is caused at low altitudes mainly by L. major (which has an animal reservoir, rodents such as mouse) and in swampy regions and high altitudes by L. tropica (which has no animal reservoir). L. aethiopica and L. major lead to disseminated ulcers in Saudi Arabia, Yemen, Iraq, Iran, Pakistan, India, Tunisia, Sudan and Ethiopia, whose main electrophoretic isozyme pattern Zymodeme in Saudi Arabia is LON-4.

scholarly journals Disuccinyl Betulin Triggers Metacaspase-Dependent Endonuclease G-Mediated Cell Death in Unicellular Protozoan Parasite Leishmania donovani

2014 ◽  
Vol 58 (4) ◽  
pp. 2186-2201 ◽  
Author(s):  
Sayan Chowdhury ◽  
Tulika Mukherjee ◽  
Somenath Roy Chowdhury ◽  
Souvik Sengupta ◽  
Sibabrata Mukhopadhyay ◽  
...  
Keyword(s):  
Cell Death ◽  
Leishmania Donovani ◽  
Protozoan Parasite ◽  
Degradation Process ◽  
Dna Lesions ◽  
Death Process ◽  
Unicellular Organism ◽  
Content Type ◽  
Atp Production ◽  
Endonuclease G

ABSTRACTThe unicellular organismLeishmaniaundergoes apoptosis-like cell death in response to external stress or exposure to antileishmanial agents. Here, we showed that 3-O,28-O-disuccinyl betulin (DiSB), a potent topoisomerase type IB inhibitor, induced parasitic cell death by generating oxidative stress. The characteristic feature of the death process resembled the programmed cell death (PCD) seen in higher eukaryotes. In the current study, the generation of reactive oxygen species (ROS), followed by the depolarization of mitochondrial membrane potential (ΔΨm), caused a loss in ATP production inLeishmaniaparasites. This further gave positive feedback to produce a large amount of ROS, which in turn caused oxidative DNA lesions and genomic DNA fragmentation. The treatment of promastigotes with DiSB induced high expression levels of metacaspase protein that led to cell death in this unicellular organism. The PCD was insensitive to benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD-fmk), suggesting that the death process was not associated with the activation of caspases. DiSB treatment translocatedLeishmania donovaniendonuclease G (LdEndoG) from mitochondria to the nucleus, which was responsible for the DNA degradation process. Conditional antisense knockdown ofL. donovanimetacaspase (LdMC), as well as EndoG, -subverted death of the parasite and rescued cell cycle arrest in G1phase. The present study on the effector molecules associated with the PCD pathway of the parasite should help to manifest the mechanisms of PCD and also might be exploited in antileishmanial chemotherapy.

Coenzyme A and its derivatives: renaissance of a textbook classic

2014 ◽  
Vol 42 (4) ◽  
pp. 1025-1032 ◽  
Author(s):  
Frederica L. Theodoulou ◽  
Ody C.M. Sibon ◽  
Suzanne Jackowski ◽  
Ivan Gout
Keyword(s):  
Translational Regulation ◽  
Biosynthetic Pathway ◽  
Coenzyme A ◽  
Cellular Metabolism ◽  
Biosynthetic Enzymes ◽  
Protein Acetylation ◽  
Heat Stable ◽  
Structural Differences ◽  
Challenges And Opportunities ◽  
Metabolic Reactions

In 1945, Fritz Lipmann discovered a heat-stable cofactor required for many enzyme-catalysed acetylation reactions. He later determined the structure for this acetylation coenzyme, or coenzyme A (CoA), an achievement for which he was awarded the Nobel Prize in 1953. CoA is now firmly embedded in the literature, and in students’ minds, as an acyl carrier in metabolic reactions. However, recent research has revealed diverse and important roles for CoA above and beyond intermediary metabolism. As well as participating in direct post-translational regulation of metabolic pathways by protein acetylation, CoA modulates the epigenome via acetylation of histones. The organization of CoA biosynthetic enzymes into multiprotein complexes with different partners also points to close linkages between the CoA pool and multiple signalling pathways. Dysregulation of CoA biosynthesis or CoA thioester homoeostasis is associated with various human pathologies and, although the biochemistry of CoA biosynthesis is highly conserved, there are significant sequence and structural differences between microbial and human biosynthetic enzymes. Therefore the CoA biosynthetic pathway is an attractive target for drug discovery. The purpose of the Coenzyme A and Its Derivatives in Cellular Metabolism and Disease Biochemical Society Focused Meeting was to bring together researchers from around the world to discuss the most recent advances on the influence of CoA, its biosynthetic enzymes and its thioesters in cellular metabolism and diseases and to discuss challenges and opportunities for the future.

Sign in / Sign up

Export Citation Format

Share Document