Phosphatidylethanolamine Synthesis in the Parasite Mitochondrion Is Required for Efficient Growth but Dispensable for Survival of Toxoplasma gondii

Hartmann, Anne; Hellmund, Maria; Lucius, Richard; Voelker, Dennis R.; Gupta, Nishith

doi:10.1074/jbc.m113.509406

Cited by 38 publications

(60 citation statements)

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“…It is notable that each of the major phospholipid classes detected in these analyses contained distinctive acyl chain compositions which likely reflects differences in their subcellular sites of synthesis as well as the extent to which their acyl chain composition is remodeled through acyl exchange reactions. For example, PE is synthesized via multiple pathways in the ER, mitochondrion, dense granules and the PV (Hartmann et al ., ), while PC is primarily synthesized by the Kennedy pathway in the ER or late secretory pathway (Gupta et al ., ). PC and other phospholipids may also be actively scavenged from the host cell.…”

Section: Discussionmentioning

confidence: 99%

The intracellular parasite Toxoplasma gondii depends on the synthesis of long‐chain and very long‐chain unsaturated fatty acids not supplied by the host cell

Ramakrishnan

Docampo

MacRae

et al. 2015

Molecular Microbiology

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SUMMARY Apicomplexa are parasitic protozoa that cause important human diseases including malaria, cryptosporidiosis and toxoplasmosis. The replication of these parasites within their target host cell is dependent on both salvage as well as de novo synthesis of fatty acids. In T. gondii, fatty acid synthesis via the apicoplast-localized FASII is essential for pathogenesis, while the role of two other fatty acid biosynthetic complexes remains unclear. Here we demonstrate that the ER-localized fatty acid elongation (ELO) is essential for parasite growth. Conditional knock-down of the non-redundant hydroxyacyl-CoA dehydratase and enoyl-CoA reductase enzymes in the ELO pathway severely repressed intracellular parasite growth. 13C-glucose and 13C-acetate labeling and comprehensive lipidomic analyses of these mutants showed a selective defect in synthesis of unsaturated long and very long chain fatty acids (LCFAs and VLCFAs) and depletion of phosphatidylinositol and phosphatidylethanolamine species containing unsaturated LCFAs and VLCFAs. This requirement for ELO pathway was by-passed by supplementing the media with specific fatty acids, indicating active, but inefficient import of host fatty acids. Our experiments highlight a gap between the fatty acid needs of the parasite and availability of specific fatty acids in the host cell that the parasite has to close using a dedicated synthesis and modification pathway.

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Section: Discussionmentioning

confidence: 99%

The intracellular parasite Toxoplasma gondii depends on the synthesis of long‐chain and very long‐chain unsaturated fatty acids not supplied by the host cell

Ramakrishnan

Docampo

MacRae

et al. 2015

Molecular Microbiology

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“…Plaque assays were done in 6-well plates seeded with HFF cells (42). Inhibitors were dissolved in DMSO, and then mixed with 2 ml of culture media before diluting them to desired amounts into each well.…”

Section: Parasite Growth Assaysmentioning

confidence: 99%

The intracellular parasite Toxoplasma gondii harbors three druggable FNT-type formate and l-lactate transporters in the plasma membrane

Erler

Ren

Gupta

et al. 2018

Journal of Biological Chemistry

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Edited by Karen G. FlemingToxoplasma gondii is a globally prevalent parasitic protist. It is well-known for its ability to infect almost all nucleated vertebrate cells, which is reflected by its unique metabolic architecture. Its fast-growing tachyzoite stage catabolizes glucose via glycolysis to yield L-lactate as a major by-product that must be exported from the cell to prevent toxicity; the underlying mechanism remains to be elucidated, however. Herein, we report three formate-nitrite transporter (FNT)-type monocarboxylate/proton symporters located in the plasma membrane of the T. gondii tachyzoite stage. We observed that all three proteins transport both L-lactate and formate in a pH-dependent manner and are inhibited by 2-hydroxy-chromanones (a class of small synthetic molecules). We also show that these compounds pharmacologically inhibit T. gondii growth. Using a chemical biology approach, we identified the critical residues in the substrateselectivity region of the parasite transporters that determine differential specificity and sensitivity toward both substrates and inhibitors. Our findings further indicate that substrate specificity in FNT family proteins from T. gondii has evolved such that a functional repurposing of prokaryotic-type transporters helps fulfill a critical metabolic role in a clinically important parasitic protist. In summary, we have identified and characterized the lactate transporters of T. gondii and have shown that compounds blocking the FNTs in this parasite can inhibit its growth, suggesting that these transporters could have utility as potential drug targets.

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“…Whereas choline and ethanolamine are used to produce phosphatidylcholine and phosphatidylethanolamine, respectively, serine is adeptly utilized to synthesize both phosphatidylserine and phosphatidylethanolamine (17,33). Indeed, radiolabeling with two of three major precursors of phospholipid synthesis (choline and serine) was decreased in the ⌬tggt1 strain (Fig.…”

Section: Glucose and Glutamine Together Facilitate The Biogenesis Ofmentioning

confidence: 99%

Metabolic Cooperation of Glucose and Glutamine Is Essential for the Lytic Cycle of Obligate Intracellular Parasite Toxoplasma gondii

Nitzsche

Zagoriy²,

Lucius

et al. 2016

Journal of Biological Chemistry

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Toxoplasma gondii is a widespread protozoan parasite infecting nearly all warm-blooded organisms. Asexual reproduction of the parasite within its host cells is achieved by consecutive lytic cycles, which necessitates biogenesis of significant energy and biomass. Here we show that glucose and glutamine are the two major physiologically important nutrients used for the synthesis of macromolecules (ATP, nucleic acid, proteins, and lipids) in T. gondii, and either of them is sufficient to ensure the parasite survival. The parasite can counteract genetic ablation of its glucose transporter by increasing the flux of glutamine-derived carbon through the tricarboxylic acid cycle and by concurrently activating gluconeogenesis, which guarantee a continued biogenesis of ATP and biomass for host-cell invasion and parasite replication, respectively. In accord, a pharmacological inhibition of glutaminolysis or oxidative phosphorylation arrests the lytic cycle of the glycolysis-deficient mutant, which is primarily a consequence of impaired invasion due to depletion of ATP. Unexpectedly, however, intracellular parasites continue to proliferate, albeit slower, notwithstanding a simultaneous deprivation of glucose and glutamine. A growth defect in the glycolysis-impaired mutant is caused by a compromised synthesis of lipids, which cannot be counterbalanced by glutamine but can be restored by acetate. Consistently, supplementation of parasite cultures with exogenous acetate can amend the lytic cycle of the glucose transport mutant. Such plasticity in the parasite's carbon flux enables a growth-and-survival trade-off in assorted nutrient milieus, which may underlie the promiscuous survival of T. gondii tachyzoites in diverse host cells. Our results also indicate a convergence of parasite metabolism with cancer cells.Toxoplasma gondii is an opportunistic intracellular pathogen of the phylum Apicomplexa that inflicts life-threatening acute and chronic infections in humans and animals (1). The parasite causes ocular and cerebral toxoplasmosis and sporadic abortion/stillbirth as a consequence of severe tissue necrosis in individuals with a poor or weakened immunity, e.g. neonates, AIDS, and organ-transplantation patients. The lytic cycle of T. gondii starts with the active energy-dependent invasion of host cells by the tachyzoite stage that is followed by rapid intracellular replication, egress by host-cell lysis, and reinvasion of adjacent cells. Upon infection of host cells in vitro, one tachyzoite can usually produce 32-64 daughter cells within a nonfusogenic vacuole, which provides a safe niche for the parasite replication and an interface for acquisition of host resources (1). Such an efficient asexual reproduction and concomitant expansion of the parasite vacuole requires a significant nutritional import and biomass synthesis within the parasite. Moreover, tachyzoites likely need to adjust metabolism according to variable bioenergetic demands of extracellular and intracellular states as well as to the nutritional cues in distinct...

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Phosphatidylethanolamine Synthesis in the Parasite Mitochondrion Is Required for Efficient Growth but Dispensable for Survival of Toxoplasma gondii

Cited by 38 publications

References 50 publications

The intracellular parasite Toxoplasma gondii depends on the synthesis of long‐chain and very long‐chain unsaturated fatty acids not supplied by the host cell

The intracellular parasite Toxoplasma gondii depends on the synthesis of long‐chain and very long‐chain unsaturated fatty acids not supplied by the host cell

The intracellular parasite Toxoplasma gondii harbors three druggable FNT-type formate and l-lactate transporters in the plasma membrane

Metabolic Cooperation of Glucose and Glutamine Is Essential for the Lytic Cycle of Obligate Intracellular Parasite Toxoplasma gondii

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