Nutrition and Biosynthetic Capabilities of Flagellates: Problems of
            <i>in vitro</i>
            Cultivation and Differentiation

Trager, William

doi:10.1002/9780470720035.ch12

Cited by 13 publications

(3 citation statements)

References 70 publications

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“…Trypanosomatid parasites are auxotrophic for haem [the Fe 2+ and protoporphyrin IX (PPIX) complex], which is an essential molecule in all aerobic organisms, due to the absence of most of its biosynthetic pathway (Trager, 1974; Opperdoes and Coombs, 2007). Trypanosomatids must therefore acquire haem from the host, thus making the proteins involved in porphyrin trafficking attractive candidates as targets for the design of new drugs.…”

Section: Introductionmentioning

confidence: 99%

A new ATP‐binding cassette protein is involved in intracellular haem trafficking in Leishmania

Campos‐Salinas

Cabello‐Donayre

García-Hernández

et al. 2011

Molecular Microbiology

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SummaryThe characterization of LABCG5, a new intracellular ATP-binding cassette protein in Leishmania donovani, is described. Unlike other ABCG halftransporters, LABCG5 is not involved in either drug resistance or phospholipid efflux. However, we provide evidence suggesting that this protein is involved in intracellular haem trafficking. Thus, downregulation of LABCG5 function produced upon overexpression of an inactive version of the protein caused a dramatic growth arrest unless a haemin supplement was added or the mutated gene was eliminated. Supplementation with haemoglobin, an upstream metabolite normally sufficient to meet parasite haem requirements, was unable to rescue the growth defect phenotype. Haemoglobin endocytosis was not hampered in dominant-negative parasites and neither was haem uptake, a process that we show here to be dependent on a specific transporter. In contrast, LABCG5 function was required for the correct intracellular trafficking of haemoglobin-bound porphyrins to the mitochondria, not affecting the routing of free haem. Finally, LABCG5 binds haem through hydrophobic and electrostatic interactions. Altogether, these data suggest that LABCG5 is involved in the salvage of the haem released after the breakdown of internalized haemoglobin. As Leishmania is auxotrophic for haem, the pharmacological targeting of this route could represent a novel approach to control fatal visceral leishmaniasis.

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Section: Introductionmentioning

confidence: 99%

A new ATP‐binding cassette protein is involved in intracellular haem trafficking in Leishmania

Campos‐Salinas

Cabello‐Donayre

García-Hernández

et al. 2011

Molecular Microbiology

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“…Heme auxotrophs, e.g., the trypanosomatid protozoa, do not convert exogenously supplied ALA to porphyrins when the heme biosynthetic pathway is either absent or incomplete (26,30,36). Among these single-cell parasites, Leishmania spp.…”

mentioning

confidence: 99%

Delta-Aminolevulinate-Induced Host-Parasite Porphyric Disparity for Selective Photolysis of Transgenic Leishmania in the Phagolysosomes of Mononuclear Phagocytes: a Potential Novel Platform for Vaccine Delivery

et al. 2012

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“…Like most trypanosomatid parasites, Leishmania is auxotrophous for heme and must acquire this essential porphyrin from the host [ 4 , 5 ]. Therefore, proteins involved in porphyrin uptake and intra-cellular trafficking could represent attractive targets for drug development.…”

Section: Introductionmentioning

confidence: 99%

LmABCB3, an atypical mitochondrial ABC transporter essential for Leishmania major virulence, acts in heme and cytosolic iron/sulfur clusters biogenesis

et al. 2016

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BackgroundMitochondria play essential biological functions including the synthesis and trafficking of porphyrins and iron/sulfur clusters (ISC), processes that in mammals involve the mitochondrial ATP-Binding Cassette (ABC) transporters ABCB6 and ABCB7, respectively. The mitochondrion of pathogenic protozoan parasites such as Leishmania is a promising goal for new therapeutic approaches. Leishmania infects human macrophages producing the neglected tropical disease known as leishmaniasis. Like most trypanosomatid parasites, Leishmania is auxotrophous for heme and must acquire porphyrins from the host.MethodsLmABCB3, a new Leishmania major protein with significant sequence similarity to human ABCB6/ABCB7, was identified and characterized using bioinformatic tools. Fluorescent microscopy was used to determine its cellular localization, and its level of expression was modulated by molecular genetic techniques. Intracellular in vitro assays were used to demonstrate its role in amastigotes replication, and an in vivo mouse model was used to analyze its role in virulence. Functional characterization of LmABCB3 was carried out in Leishmania promastigotes and Saccharomyces cerevisiae. Structural analysis of LmABCB3 was performed using molecular modeling software.ResultsLmABCB3 is an atypical ABC half-transporter that has a unique N-terminal extension not found in any other known ABC protein. This extension is required to target LmABCB3 to the mitochondrion and includes a potential metal-binding domain. We have shown that LmABCB3 interacts with porphyrins and is required for the mitochondrial synthesis of heme from a host precursor. We also present data supporting a role for LmABCB3 in the biogenesis of cytosolic ISC, essential cofactors for cell viability in all three kingdoms of life. LmABCB3 fully complemented the severe growth defect shown in yeast lacking ATM1, an orthologue of human ABCB7 involved in exporting from the mitochondria a gluthatione-containing compound required for the generation of cytosolic ISC. Indeed, docking analyzes performed with a LmABCB3 structural model using trypanothione, the main thiol in this parasite, as a ligand showed how both, LmABCB3 and yeast ATM1, contain a similar thiol-binding pocket. Additionally, we show solid evidence suggesting that LmABCB3 is an essential gene as dominant negative inhibition of LmABCB3 is lethal for the parasite. Moreover, the abrogation of only one allele of the gene did not impede promastigote growth in axenic culture but prevented the replication of intracellular amastigotes and the virulence of the parasites in a mouse model of cutaneous leishmaniasis.ConclusionsAltogether our results present the previously undescribed LmABCB3 as an unusual mitochondrial ABC transporter essential for Leishmania survival through its role in the generation of heme and cytosolic ISC. Hence, LmABCB3 could represent a novel target to combat leishmaniasis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-1284-5) contains supplementary ma...

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Nutrition and Biosynthetic Capabilities of Flagellates: Problems of in vitro Cultivation and Differentiation

Cited by 13 publications

References 70 publications

A new ATP‐binding cassette protein is involved in intracellular haem trafficking in Leishmania

A new ATP‐binding cassette protein is involved in intracellular haem trafficking in Leishmania

Delta-Aminolevulinate-Induced Host-Parasite Porphyric Disparity for Selective Photolysis of Transgenic Leishmania in the Phagolysosomes of Mononuclear Phagocytes: a Potential Novel Platform for Vaccine Delivery

LmABCB3, an atypical mitochondrial ABC transporter essential for Leishmania major virulence, acts in heme and cytosolic iron/sulfur clusters biogenesis

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