Enhanced Metabolism of
            <i>Leishmania donovani</i>
            Amastigotes at Acid
            <i>p</i>
            H: an Adaptation for Intracellular Growth

Mukkada, Antony J.; Meade, John C.; Glaser, Theresa A.; Bonventre, Peter F.

doi:10.1126/science.4035350

Cited by 105 publications

(61 citation statements)

References 37 publications

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“…These results imply that glucose transporter expression is essential for amastigote viability and were unanticipated, given that glucose uptake (7) and catabolism (42) are thought to be down-regulated in amastigotes. Furthermore, the failure of ⌬lmgt null mutants to grow as CF amastigotes and the inability of WT parasites to survive as CF amastigotes in medium devoid of glucose further imply that glucose is an essential nutrient for amastigotes and that glucose transporter null mutants are not viable as amastigotes for this reason.…”

Section: Discussionmentioning

confidence: 94%

Genetic characterization of glucose transporter function inLeishmania mexicana

Burchmore

Rodriguez‐Contreras

McBride

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

127

165

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Both insect and mammalian life cycle stages of Leishmania mexicana take up glucose and express all three isoforms encoded by the LmGT glucose transporter gene family. To evaluate glucose transporter function in intact parasites, a null mutant line has been created by targeted disruption of the LmGT locus that encompasses the LmGT1, LmGT2, and LmGT3 genes. This Δlmgt null mutant exhibited no detectable glucose transport activity. The growth rate of the Δlmgt knockout in the promastigote stage was reduced to a rate comparable with that of WT cells grown in the absence of glucose. Δlmgt cells also exhibited dramatically reduced infectivity to macrophages, demonstrating that expression of LmGT isoforms is essential for viability of amastigotes. Furthermore, WT L. mexicana were not able to grow as axenic culture form amastigotes if glucose was withdrawn from the medium, implying that glucose is an essential nutrient in this life cycle stage. Expression of either LmGT2 or LmGT3, but not of LmGT1, in Δlmgt null mutants significantly restored growth as promastigotes, but only LmGT3 expression substantially rescued amastigote growth in macrophages. Subcellular localization of the three isoforms was investigated in Δlmgt cells expressing individual LmGT isoforms. Using anti-LmGT antiserum and GFP-tagged LmGT fusion proteins, LmGT2 and LmGT3 were localized to the cell body, whereas LmGT1 was localized specifically to the flagellum. These results establish that each glucose transporter isoform has distinct biological functions in the parasite

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Section: Discussionmentioning

confidence: 94%

Genetic characterization of glucose transporter function inLeishmania mexicana

Burchmore

Rodriguez‐Contreras

McBride

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

127

165

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“…Parasites change shape from elongated to spherical and lose most of their flagellum. They undergo a major shift in metabolism, especially in the rate and pH optima for several processes, including DNA synthesis [5] and nutrient uptake [6]. A number of amastigote-specific genes have been identified, including a 3′-nucleotidase [7], the A2 gene family [8,9], HSP100 [10], and a MAP kinase, LMPMK [11].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Leishmania donovani transcriptome reveals an ordered progression of transient and permanent changes in gene expression during differentiation

Saxena

Lahav

Holland

et al. 2007

Molecular and Biochemical Parasitology

148

140

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Leishmania donovani is an intracellular protozoan parasite that causes kala-azar in humans. During infection the extracellular insect forms (promastigotes) undergo rapid differentiation to intracellular amastigotes that proliferates in phagolysosomes of mammalian macrophages. We used microarraybased expression profiling to investigate the time-course of changes in RNA abundance during promastigote-to-amastigote differentiation in a host-free system that mimics this process. These studies revealed that several hundred genes underwent an ordered progression of transient or permanent up-and down-regulation during differentiation. Genes that were permanently upregulated in amastigotes were enriched for transporters and surface proteins, but under-represented in genes involved in protein and other metabolism. Most of these changes occurred late in the differentiation process, when morphological differentiation was essentially complete. Downregulated genes were over-represented in those involved in cell motility, growth and/or maintenance, and these changes generally occurred earlier in the process. Genes that were transiently up-or downregulated during differentiation included those encoding heat shock proteins, ubiquitin hydrolases, RNA binding proteins, protein kinases, a protein phosphatase, and a histone deacetylase. These results suggest that changes in mRNA abundance may be important in signal transduction, as well as protein and mRNA turnover, during differentiation. In addition to these mRNA changes, other transcripts including one or more rRNAs and snoRNAs, and non-coding RNAs from several telomeres, also showed substantial changes in abundance during the differentiation process. This paper provides the first genome-scale quantitative analysis of gene expression during the transition from promastigotes to amastigotes and demonstrates the utility of the host-free differentiation system.

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“…In comparison, the promastigote-to-amastigote cytodifferentiation is a profound morphological and physiological transformation. During differentiation, the parasite loses its flagellum, rounds up, changes its glycoconjugate coat (13,21,22,39), and starts to express a set of metabolic enzymes optimally active at low pHs (14,25 functions of its host cell, including oxygen metabolite-mediated killing and the capacity of the macrophage to act as an efficient antigen-presenting cell (5, 20). Glycoconjugates that coat the promastigote have been shown to play a critical role in the mechanism of entry of the parasite into its host cell and in the modulation of the host immune response (reviewed in references 24 and 38).…”

mentioning

confidence: 99%

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

Charest¹,

1994

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Leishmania protozoans are the causative agents of human leishmaniasis, which includes a spectrum of diseases ranging from self-healing skin ulcers to fatal visceral infections. Leishmania donovani causes visceral leishmaniasis, also known as kala-azar, which has a high mortality rate if not treated. The Leishmania protozoans exist as extracellular flagellated promastigotes in the alimentary tract of the sand fly and are transmitted to the mammalian hosts through the bite of the insect. Once injected through the skin, the promastigotes are taken up by macrophages, rapidly differentiate into amastigotes, and start to multiply within the phagolysosomal compartment. As the infected cells rupture, amastigotes subsequently infect other macrophages, giving rise to the various symptoms associated with leishmaniasis (23).While in the midgut of the insect, newly transformed promastigotes, functionally avirulent, progressively acquire capacity for infection and migrate to the mouthparts (30, 32). This process, termed metacyclogenesis, is concurrent with the differential expression of major surface glycoconjugates which mediate the migration of promastigotes in the alimentary tract and prepare the organism for the serum environment (27,28,31,33). In comparison, the promastigote-to-amastigote cytodifferentiation is a profound morphological and physiological transformation. During differentiation, the parasite loses its flagellum, rounds up, changes its glycoconjugate coat (13,21,22,39), and starts to express a set of metabolic enzymes optimally active at low pHs (14,25 functions of its host cell, including oxygen metabolite-mediated killing and the capacity of the macrophage to act as an efficient antigen-presenting cell (5, 20). Glycoconjugates that coat the promastigote have been shown to play a critical role in the mechanism of entry of the parasite into its host cell and in the modulation of the host immune response (reviewed in references 24 and 38).Because of difficulties in obtaining a sufficient number of pure and viable amastigotes, the biology of this form of the parasite has not been well characterized. The importance of the promastigote-amastigote cytodifferentiation for the establishment of infection in the mammalian host has prompted us to identify molecular events involved in this process. Our approach was to identify Leishmania genes developmentally expressed during the amastigote stage. Our assumption was that genes expressed only by amastigotes were likely to be essential for the survival of the parasite in its human host.In this study, we have characterized an amastigote-stagespecific gene (A2 gene) and determined the physiological conditions required to induce its expression. We also demonstrate that the A2 gene product is recognized by serum from a kala-azar patient and has identity with a major antigen developmentally expressed by the pathologic forms of the malariaassociated protozoan Plasmodium falciparum. These results suggest that the Leishmania and Plasmodium parasites, phylogenetically distant par...

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Enhanced Metabolism of Leishmania donovani Amastigotes at Acid p H: an Adaptation for Intracellular Growth

Cited by 105 publications

References 37 publications

Genetic characterization of glucose transporter function inLeishmania mexicana

Genetic characterization of glucose transporter function inLeishmania mexicana

Analysis of the Leishmania donovani transcriptome reveals an ordered progression of transient and permanent changes in gene expression during differentiation

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

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