Differential contribution of two organelles of endosymbiotic origin to iron-sulfur cluster synthesis and overall fitness in Toxoplasma

Pamukcu, Sarah; Cerutti, Aude; Hem, Sonia; Rofidal, Valérie; Besteiro, Sébastien

doi:10.1101/2021.01.28.428257

Cited by 6 publications

(39 citation statements)

References 128 publications

(193 reference statements)

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“…Transcriptional control of IscU by iron levels has been observed in a number of organisms (Garland et al, 1999;Tong and Rouault, 2006) and regulation of an IscA homolog by iron has been observed in bacteria (Andrews et al, 2003). Given the recent interest in iron sulfur biogenesis in T. gondii as a target for drug development (Aw et al, 2021;Pamukcu et al, 2021), these findings suggest a currently unknown mechanism regulating this essential metabolic pathway. We also see regulation of RNR, an iron-containing enzyme, and of several genes with predicted DNA or RNA binding motifs.…”

Section: Discussionmentioning

confidence: 92%

The vacuolar iron transporter mediates iron detoxification inToxoplasma gondii

Aghabi

Sloan

Dou

et al. 2021

Preprint

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Iron is essential to living cells, acting as a cofactor in a number of essential enzymes in metabolism; however, iron requires proper storage or it can be dangerous to the cell. In both yeast and plants, iron is stored in a vacuole through the action of a vacuolar iron transporter (VIT). This transporter is conserved in the apicomplexan family of obligate intracellular parasites, including in Toxoplasma gondii, a pathogen of medical and veterinary importance. Here, we assess the role of VIT in T. gondii. We show that deletion of VIT causes a slight growth defect in vitro, however leads to hypersensitivity in the presence of excess iron, confirming its essential role in iron detoxification in the parasite. In the absence of VIT, parasites contain less iron and are at a growth disadvantage when moving into an iron-depleted environment. We show parasite VIT expression is regulated by environmental iron levels at both the transcript and protein level, and by altering the distribution of VIT within the cell. In the absence of VIT, we find that the T. gondii responds by altering expression of genes with a role in iron metabolism and by increasing the activity of the antioxidant protein catalase. We also show that iron detoxification has an important role both in parasite survival within macrophages and in pathogenesis in a mouse model. Together, by demonstrating a critical role for VIT during iron detoxification in T. gondii, we reveal the importance of iron storage in the parasite and provide the first insight into the machinery involved.

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Section: Discussionmentioning

confidence: 92%

The vacuolar iron transporter mediates iron detoxification inToxoplasma gondii

Aghabi

Sloan

Dou

et al. 2021

Preprint

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“…We first assessed whether depletion of TgSUFC led to a partial apicoplast loss, as was previously shown for TgNFS2 (12). Although slowed down in growth, some parasites eventually egressed during the course of the experiments and were used to reinvade host cells, and were kept for a total of 5 days in the presence of ATc (Fig.…”

Section: Resultsmentioning

confidence: 98%

“…Hence, this highlighted an early and important defect in plasma membrane synthesis and/or segregation during daughter cell budding. We previously observed major cell division defects after long term (five days or more) continuous incubation of cKD TgNFS2-HA parasites with ATc (12). When assessing the cKD TgSUFC-HA parasites in the same conditions, co-staining with apicoplast and IMC markers revealed similar defects, including organelle segregation problems and an abnormal membranous structures (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Computational prediction of the Fe-S proteome combined with hyperLOPIT localization data suggests there is a limited number of apicoplast proteins potentially containing Fe-S clusters (12). However, these candidates are supposedly very important for the parasite.…”

Section: Resultsmentioning

confidence: 99%

“…To better understand the contribution of the SUF pathway to T. gondii viability, we have generated a conditional mutant for the scaffold protein TgSUFC and conducted a thorough phenotypic characterization of this mutant, together with the TgNFS2 mutant we have previously generated (12). Our results confirm that inactivating the plastid-hosted SUF pathway in T. gondii leads to irreversible and marked effects on membrane homeostasis, impacting the division process and parasite viability.…”

Section: Introductionmentioning

confidence: 99%

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Disrupting the plastid-hosted iron-sulfur cluster biogenesis pathway in Toxoplasma gondii has pleiotropic effects irreversibly impacting parasite viability

Renaud

Pamukcu

Cerutti

et al. 2022

Preprint

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Like many other apicomplexan parasites, Toxoplasma gondii contains a plastid harbouring key metabolic pathways, including the SUF pathway that is involved in the biosynthesis of iron-sulfur clusters. These cofactors are key for a variety of proteins involved in important metabolic reactions, potentially including plastidic pathways for the synthesis of isoprenoid and fatty acids. It was shown previously that impairing the NFS2 cysteine desulfurase, involved in the first step of the SUF pathway, leads to an irreversible killing of intracellular parasites. However, the metabolic impact of disrupting the pathway remained unexplored. We have generated another mutant of the pathway, deficient for the SUFC ATPase, and we have investigated in details the phenotypic consequences of TgNFS2 and TgSUFC depletion on parasite homeostasis. Our analysis confirms that Toxoplasma SUF mutants are severely and irreversibly impacted in growth: cell division and membrane homeostasis are particularly affected. Lipidomic analysis suggests a defect in apicoplast-generated fatty acids, along with a simultaneous increase in scavenging of host-derived lipids. However, addition of exogenous lipids did not allow full restauration of growth, suggesting other more important cellular functions were impacted in addition to fatty acid synthesis. For instance, we have shown that the SUF pathway is also key for generating isoprenoid-derived precursors necessary for the proper targeting of GPI-anchored proteins as well as for the parasite gliding motility. Thus, plastid-generated iron-sulfur clusters support the functions of proteins involved in several vital downstream cellular pathways, which implies the SUF machinery may be explored for discovering new potential anti-Toxoplasma targets.

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