Transformed<i>Toxoplasma gondii</i>Tachyzoites Expressing the Circumsporozoite Protein of<i>Plasmodium knowlesi</i>Elicit a Specific Immune Response in Rhesus Monkeys

Cristina, Manlio Di; Ghouze, Firman; Kocken, Clemens H M; Naitza, Silvia; Cellini, Pamela; Soldati, Dominique; Thomas, Alan W.; Crisanti, Andrea

doi:10.1128/iai.67.4.1677-1682.1999

Cited by 24 publications

(1 citation statement)

References 33 publications

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“…Human foreskin fibroblasts (HFFs) were grown and maintained in Dulbecco’s modified Eagle’s medium containing 10% fetal bovine serum (Thermo Fisher), and 50µg/ml penicillin-streptomycin (media called D10). All T. gondii strains were propagated in vitro by serial passage on HFF monolayers (69). In vitro tachyzoite-to-bradyzoite conversion was induced by exposing parasite cultures to pH 8.2 (70, 71).…”

Section: Methodsmentioning

confidence: 99%

AToxoplasma gondiiputative arginine transporter localizes to the plant-like vacuolar compartment and controls parasite extracellular survival and stage differentiation

Piro,

Masci,

Kannan

et al. 2023

Preprint

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Toxoplasma gondiiis a protozoan parasite that infects a broad spectrum of hosts and can colonize many organs and cell types. The ability to reside within a wide range of different niches requires substantial adaptability to diverse microenvironments. Very little is known about how this parasite senses various milieus and adapts its metabolism to survive, replicate during the acute stage, and then differentiate to the chronic stage. Most eukaryotes, from yeast to mammals, rely on a nutrient sensing machinery involving the TORC complex as master regulator of cell growth and cell cycle progression. The lysosome functions as a signaling hub where TORC complex assembles and is activated by transceptors, which both sense and transport amino acids, including the arginine transceptor SLC38A9. While most of the TORC components are lost inT. gondii, indicating the evolution of a distinct nutrient sensing mechanism, the parasite’s lysosomal plant-like vacuolar compartment (PLVAC) may still serve as a sensory platform for controlling parasite growth and differentiation. Using SLC38A9 to query theT. gondiiproteome, we identified four putative amino acid transporters, termed TgAAT1-4, that structurally resemble the SLC38A9 arginine transceptor. Assessing their expression and sub-cellular localization, we found that one of them, TgAAT1, localized to the PLVAC and is necessary for normal parasite extracellular survival and bradyzoite differentiation. Moreover, we show that TgAAT1 is involved in the PLVAC efflux of arginine, an amino acid playing a key role inT. gondiidifferentiation, further supporting the hypothesis that TgAAT1 might play a role in nutrient sensing.

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Section: Methodsmentioning

confidence: 99%

AToxoplasma gondiiputative arginine transporter localizes to the plant-like vacuolar compartment and controls parasite extracellular survival and stage differentiation

Piro,

Masci,

Kannan

et al. 2023

Preprint

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Heterologous expression in Toxoplasma gondii reveals a topogenic signal anchor in a Plasmodium apicoplast protein

et al. 2018

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Glutathione peroxidase‐like thioredoxin peroxidase (Pf TP x Gl ) is an antioxidant enzyme trafficked to the apicoplast, a secondary endosymbiotic organelle, in Plasmodium falciparum . Apicoplast trafficking signals usually consist of N‐terminal signal and transit peptides, but the trafficking signal of Pf TP x Gl appears to exhibit important differences. As transfection is a protracted process in P. falciparum , we expressed the N terminus of Pf TP x Gl as a GFP fusion protein in a related apicomplexan, Toxoplasma gondii , in order to dissect its trafficking signals. We show that Pf TP x Gl possesses an N‐terminal signal anchor that takes the protein to the endoplasmic reticulum in Toxoplasma —this is the first step in the apicoplast targeting pathway. We dissected the residues important for endomembrane system uptake, membrane anchorage, orientation, spacing, and cleavage. Protease protection assays and fluorescence complementation revealed that the C terminus of the protein lies in the ER lumen, a topology that is proposed to be retained in the apicoplast. Additionally, we examined one mutant, responsible for altered Pf TP x Gl targeting in Toxoplasma , in Plasmodium . This study has demonstrated that Pf TP x Gl belongs to an emergent class of proteins that possess signal anchors, unlike the canonical bipartite targeting signals employed for the trafficking of luminal apicoplast proteins. This work adds to the mounting evidence that the signals involved in the targeting of apicoplast membrane proteins may not be as straightforward as those of luminal proteins, and also highlights the usefulness of T. gondii as a heterologous system in certain aspects of this study, such as reducing screening time and facilitating the verification of membrane topology.

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Current and Emerging Approaches to Studying Invasion in Apicomplexan Parasites

Mital

Ward

Subcellular Biochemistry

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TransformedToxoplasma gondiiTachyzoites Expressing the Circumsporozoite Protein ofPlasmodium knowlesiElicit a Specific Immune Response in Rhesus Monkeys

Cited by 24 publications

References 33 publications

AToxoplasma gondiiputative arginine transporter localizes to the plant-like vacuolar compartment and controls parasite extracellular survival and stage differentiation

AToxoplasma gondiiputative arginine transporter localizes to the plant-like vacuolar compartment and controls parasite extracellular survival and stage differentiation

Heterologous expression in Toxoplasma gondii reveals a topogenic signal anchor in a Plasmodium apicoplast protein

Current and Emerging Approaches to Studying Invasion in Apicomplexan Parasites

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