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Guanylate binding proteins directly attack Toxoplasma gondii via supramolecular complexes.

ABSTRACT: GBPs are essential for immunity against intracellular pathogens, especially for Toxoplasma gondii control. Here, the molecular interactions of murine GBPs (mGBP1/2/3/5/6), homo- and hetero-multimerization properties of mGBP2 and its function in parasite killing were investigated by mutational, Multiparameter Fluorescence Image Spectroscopy, and live cell microscopy methodologies. Control of T. gondii replication by mGBP2 requires GTP hydrolysis and isoprenylation thus, enabling reversible oligomerization in vesicle-like structures. mGBP2 undergoes structural transitions between monomeric, dimeric and oligomeric states visualized by quantitative FRET analysis. mGBPs reside in at least two discrete subcellular reservoirs and attack the parasitophorous vacuole membrane (PVM) as orchestrated, supramolecular complexes forming large, densely packed multimers comprising up to several thousand monomers. This dramatic mGBP enrichment results in the loss of PVM integrity, followed by a direct assault of mGBP2 upon the plasma membrane of the parasite. These discoveries provide vital dynamic and molecular perceptions into cell-autonomous immunity.

SUBMITTER: Kravets E

PROVIDER: S-EPMC4786432 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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Guanylate binding proteins directly attack Toxoplasma gondii via supramolecular complexes.

Kravets Elisabeth E Degrandi Daniel D Ma Qijun Q Peulen Thomas-Otavio TO Klümpers Verena V Felekyan Suren S Kühnemuth Ralf R Weidtkamp-Peters Stefanie S Seidel Claus Am CA Pfeffer Klaus K

eLife 20160127

GBPs are essential for immunity against intracellular pathogens, especially for Toxoplasma gondii control. Here, the molecular interactions of murine GBPs (mGBP1/2/3/5/6), homo- and hetero-multimerization properties of mGBP2 and its function in parasite killing were investigated by mutational, Multiparameter Fluorescence Image Spectroscopy, and live cell microscopy methodologies. Control of T. gondii replication by mGBP2 requires GTP hydrolysis and isoprenylation thus, enabling reversible oligom ...[more]

PMID: 26814575

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Project description:Cyst formation is a key feature of the T. gondii life cycle but the genetic networks that drive this process are not yet fully characterized. To identify new components of this network, we compared T. gondii to its nearest extant relative Hammondia hammondi given the critical differences between these species in the timing and efficiency of cyst formation. Using transcriptional data from critical developmental and pH exposure time points from both species, we identified the gene TGVEG_311100, which we named Regulator of Cystogenesis 1 (ROCY1), as being both necessary and sufficient for cyst formation in T. gondii. Compared to WT parasites, TGVEG?ROCY1 parasites formed significantly fewer tissue cysts in response to alkaline pH stress in vitro and cysts were nearly undetectable in mouse brains for up to 9 weeks post-infection. Overexpression of tagged ROCY1 in WT parasites was sufficient to induce cyst formation in vitro in both WT and ROCY1-deficient parasites, demonstrating that ROCY1 is both necessary and sufficient for cyst formation. Moreover this induction of cyst formation required at least 1 of 3 predicted CCCH Zinc finger domains. Mice chronically infected with ?ROCY1 parasites had detectable tachyzoites in the brain for up to 37 days post-infection (while mice infected with WT parasites did not), and CNS transcriptional analyses at day 30 post-infection throughout the chronic phase of infection revealed inflammatory signatures consistent with acute infection in ?ROCY1 parasites compared to WT. Despite our inability to detect brain cysts in infected mice, both WT and ?ROCY1 knockout parasites reactivated after dexamethasone treatment with similar timing and magnitude for up to 5 months post infection, challenging the paradigm that long term parasite persistence in the CNS requires cyst formation. These data identify a new regulator of cyst formation in T. gondii that is both necessary and sufficient for cyst formation, and whose function relies on its conserved nucleic acid binding motif.

Dataset Information

Guanylate binding proteins directly attack Toxoplasma gondii via supramolecular complexes.

Publications

Guanylate binding proteins directly attack Toxoplasma gondii via supramolecular complexes.

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