Identification of novel rhoptry secretion factors in Toxoplasma gondii _ ND11

ABSTRACT: Apicomplexan parasites, together with ciliates and dinoflagellates, belong to the Alveolata superphylum. Apicomplexa possess secretory organelles called rhoptries that undergo regulated exocytosis during invasion. Upon injection into the host cell, rhoptry proteins support invasion, vacuole formation, and subversion of host immune function. Rhoptry exocytosis involves a “rosette” of 8 particles embedded in the plasma membrane; such peculiar structure is also conserved in Ciliata and its formation requires Alveolata-restricted “Nd” proteins. These findings point to the existence of an Alveolata-conserved mechanism for the discharge of secretory organelles, and provide proof of concept that we can decipher rhoptry exocytosis machinery using a PAN-Alveolata approach. Thus, to uncover new rhoptry secretion factors, we used the transcriptional profiles of Nd genes of the ciliate Tetrahymena thermophila to select genes that are co-regulated, and also conserved in Apicomplexa. In this way we identified two uncharacterized Tetrahymena proteins that contribute to the exocytosis of secretory organelles. They have similar architecture and show homology with Plasmodium Cysteine Repeat Modular Proteins (CRMPs), a family of proteins essential for Plasmodium transmission from the mosquito to the host. We functionally characterized the two Toxoplasma CRMPs, including their dynamic location during invasion. They are not required for rosette formation, but they are essential for rhoptry secretion, suggesting a function distinct from that of previously characterized exocytic “Nd” factors. To characterize interacting proteins we performed pull-down experiments and analyzed the eluates by liquid chromatography-tandem mass spectrometry.

INSTRUMENT(S): Q Exactive HF-X

ORGANISM(S): Toxoplasma Gondii Me49 Homo Sapiens (human)

DISEASE(S): Toxoplasmosis

SUBMITTER: Functional Proteomics Platform FPP  

LAB HEAD: Maryse Lebrun

PROVIDER: PXD031161 | Pride | 2022-10-20

REPOSITORIES: Pride