Browse
Submit Data
Databases
API
Help

Dataset Information

30 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Leishmania infantum Asparagine Synthetase A Is Dispensable for Parasites Survival and Infectivity.

ABSTRACT: A growing interest in asparagine (Asn) metabolism has currently been observed in cancer and infection fields. Asparagine synthetase (AS) is responsible for the conversion of aspartate into Asn in an ATP-dependent manner, using ammonia or glutamine as a nitrogen source. There are two structurally distinct AS: the strictly ammonia dependent, type A, and the type B, which preferably uses glutamine. Absent in humans and present in trypanosomatids, AS-A was worthy of exploring as a potential drug target candidate. Appealingly, it was reported that AS-A was essential in Leishmania donovani, making it a promising drug target. In the work herein we demonstrate that Leishmania infantum AS-A, similarly to Trypanosoma spp. and L. donovani, is able to use both ammonia and glutamine as nitrogen donors. Moreover, we have successfully generated LiASA null mutants by targeted gene replacement in L. infantum, and these parasites do not display any significant growth or infectivity defect. Indeed, a severe impairment of in vitro growth was only observed when null mutants were cultured in asparagine limiting conditions. Altogether our results demonstrate that despite being important under asparagine limitation, LiAS-A is not essential for parasite survival, growth or infectivity in normal in vitro and in vivo conditions. Therefore we exclude AS-A as a suitable drug target against L. infantum parasites.

SUBMITTER: Faria J

PROVIDER: S-EPMC4714757 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Liver infusion tryptose (LIT): the best choice for growth, viability, and infectivity of Leishmania infantum parasites.

Project description:Leishmania spp. parasites have a complex biological cycle presenting basically two different morphological stages, the amastigote and promastigote forms. In vitro cultivation allows a more complete study of the biological aspects of these parasites, indicating better conditions for infection, immunoassay tests, drug evaluations, and vaccines. Thus, we evaluated the three most used culture media for Leishmania spp., Grace's insect cell culture medium (Grace's), liver infusion tryptose (LIT), and Schneider's insect medium (Schneider's), without supplementation or supplemented with fetal calf serum (FCS) and bovine serum albumin (Albumin) to evaluate the growth, viability, and infectivity of the L. infantum promastigotes. It was observed that promastigote forms have a better growth in LIT and Schneider's with or without FCS when compared to that in Grace's. The supplementation with albumin promoted greater viability of the parasites independent of the medium. For in vitro infection of J774.A1 macrophages using light microscopy and flow cytometry analyses, FCS-supplemented LIT and Grace's promoted higher percentage of infected macrophages and parasite load compared with Schneider's media. Taken together, our results demonstrated that the supplementation of LIT culture medium with FCS is the most suitable strategy to cultivate Leishmania infantum parasites enabling the maintenance of growth and infective parasites for research uses.

| S-EPMC7544523 | biostudies-literature

Identification of adipocytes as target cells for Leishmania infantum parasites.

Project description:Leishmania infantum is the causative agent of visceral leishmaniasis transmitted by the bite of female sand flies. According to the WHO, the estimated annual incidence of leishmaniasis is one million new cases, resulting in 30,000 deaths per year. The recommended drugs for treating leishmaniasis include Amphotericin B. But over the course of the years, several cases of relapses have been documented. These relapses cast doubt on the efficiency of actual treatments and raise the question of potential persistence sites. Indeed, Leishmania has the ability to persist in humans for long periods of time and even after successful treatment. Several potential persistence sites have already been identified and named as safe targets. As adipose tissue has been proposed as a sanctuary of persistence for several pathogens, we investigated whether Leishmania infantum could be found in this tissue. We demonstrated both in cell cultures and in vivo that Leishmania infantum was able to infect adipocytes. Altogether our results suggest adipocytes as a 'safe target' for Leishmania infantum parasites.

| S-EPMC8553825 | biostudies-literature

<i>Leishmania infantum</i> isolates exhibit high infectivity and reduced susceptibility to amphotericin B.

Project description:Leishmaniasis is a neglected disease caused by a protozoan parasite of the Leishmania species in over 98 countries in five continents. Visceral leishmaniasis is one of the main forms of the disease and is mainly caused by Leishmania infantum, whose main vector is the dipteran Lutzomyia longipalpis. The presence of the vector in Uruguay was recorded for the first time in 2010 and an autochthonous outbreak of canine visceral leishmaniasis occurred in the northern locality of the country in 2015. We report the isolation in blood-free FBS-supplemented defined media of five isolates responsible for the referred outbreak, and characterize them in terms of their growth as promastigotes, infectivity and replication in human derived monocytes and drug resistance. Results indicate similar promastigote growth among the strains, enhanced infectivity and replication for the five strains isolated from the Uruguayan outbreak when compared with reference strains from South America, equivalent drug susceptibility for miltefosine and nifurtimox and a significant difference in IC50 values for amphotericin B between the Uruguayan strains, 3-4 fold higher than the reference strain.

| S-EPMC7651856 | biostudies-literature

Identification and functional characterization of a novel bacterial type asparagine synthetase A: a tRNA synthetase paralog from Leishmania donovani.

Project description:Asparagine is formed by two structurally distinct asparagine synthetases in prokaryotes. One is the ammonia-utilizing asparagine synthetase A (AsnA), and the other is asparagine synthetase B (AsnB) that uses glutamine or ammonia as a nitrogen source. In a previous investigation using sequence-based analysis, we had shown that Leishmania spp. possess asparagine-tRNA synthetase paralog asparagine synthetase A (LdASNA) that is ammonia-dependent. Here, we report the cloning, expression, and kinetic analysis of ASNA from Leishmania donovani. Interestingly, LdASNA was both ammonia- and glutamine-dependent. To study the physiological role of ASNA in Leishmania, gene deletion mutations were attempted via targeted gene replacement. Gene deletion of LdASNA showed a growth delay in mutants. However, chromosomal null mutants of LdASNA could not be obtained as the double transfectant mutants showed aneuploidy. These data suggest that LdASNA is essential for survival of the Leishmania parasite. LdASNA enzyme was recalcitrant toward crystallization so we instead crystallized and solved the atomic structure of its close homolog from Trypanosoma brucei (TbASNA) at 2.2 Å. A very significant conservation in active site residues is observed between TbASNA and Escherichia coli AsnA. It is evident that the absence of an LdASNA homolog from humans and its essentiality for the parasites make LdASNA a novel drug target.

| S-EPMC4002115 | biostudies-literature

Unravelling the proteomic signature of extracellular vesicles released by drug-resistant Leishmania infantum parasites.

Project description:Leishmaniasis constitutes the 9th largest disease burden among all infectious diseases. Control of this disease is based on a short list of chemotherapeutic agents headed by pentavalent antimonials, followed by miltefosine and amphotericin B; drugs that are far from ideal due to host toxicity, elevated cost, limited access, and high rates of drug resistance. Knowing that the composition of extracellular vesicles (EVs) can vary according to the state of their parental cell, we hypothesized that EVs released by drug-resistant Leishmania infantum parasites could contain unique and differently enriched proteins depending on the drug-resistance mechanisms involved in the survival of their parental cell line. To assess this possibility, we studied EV production, size, morphology, and protein content of three well-characterized drug-resistant L. infantum cell lines and a wild-type strain. Our results are the first to demonstrate that drug-resistance mechanisms can induce changes in the morphology, size, and distribution of L. infantum EVs. In addition, we identified L. infantum's core EV proteome. This proteome is highly conserved among strains, with the exception of a handful of proteins that are enriched differently depending on the drug responsible for induction of antimicrobial resistance. Furthermore, we obtained the first snapshot of proteins enriched in EVs released by antimony-, miltefosine- and amphotericin-resistant parasites. These include several virulence factors, transcription factors, as well as proteins encoded by drug-resistance genes. This detailed study of L. infantum EVs sheds new light on the potential roles of EVs in Leishmania biology, particularly with respect to the parasite's survival in stressful conditions. This work outlines a crucial first step towards the discovery of EV-based profiles capable of predicting response to antileishmanial agents.

| S-EPMC7365475 | biostudies-literature

Geographic Origin and Vertical Transmission of Leishmania infantum Parasites in Hunting Hounds, United States.

Project description:Vertical transmission of leishmaniasis is common but is difficult to study against the background of pervasive vector transmission. We present genomic data from dogs in the United States infected with Leishmania infantum parasites; these infections have persisted in the apparent absence of vector transmission. We demonstrate that these parasites were introduced from the Old World separately and more recently than L. infantum from South America. The parasite population shows unusual genetics consistent with a lack of meiosis: a high level of heterozygous sites shared across all isolates and no decrease in linkage with genomic distance between variants. Our data confirm that this parasite population has been evolving with little or no sexual reproduction. This demonstration of vertical transmission has profound implications for the population genetics of Leishmania parasites. When investigating transmission in complex natural settings, considering vertical transmission alongside vector transmission is vital.

| S-EPMC9155895 | biostudies-literature

Leishmania infantum

Project description:Leishmania infantum Raw sequence reads

| PRJNA494801 | ENA

Leishmania infantum

Project description:Comparative genomic hybridization of strains of Leishmania infantum wild-type and five independent 5-fluorouracil resistant mutant.

| PRJNA196514 | ENA

Leishmania infantum

Project description:Transcriptional analysis of Leishmania infantum antimony resistant strains using full-genome DNA microarrays

| PRJNA117733 | ENA

Leishmania infantum

Project description:Leishmania infantum Genome sequencing and assembly

| PRJNA357452 | ENA