Essential function of the alveolin network in the subpellicular microtubules and conoid assembly in Toxoplasma gondii

Nicolò Tosetti, Nicolas Dos Santos Pacheco, Eloïse Bertiaux, Bohumil Maco, Lorène Bournonville, Virginie Hamel, Paul Guichard, Dominique Soldati-Favre
2020 eLife  
The coccidian subgroup of Apicomplexa possesses an apical complex harboring a conoid, made of unique tubulin polymer fibers. This enigmatic organelle extrudes in extracellular invasive parasites and is associated to the apical polar ring (APR). The APR serves as microtubule-organizing center for the 22 subpellicular microtubules (SPMTs) that are linked to a patchwork of flattened vesicles, via an intricate network composed of alveolins. Here, we capitalize on ultrastructure expansion microscopy
more » ... (U-ExM) to localize the Toxoplasma gondii Apical Cap protein 9 (AC9) and its partner AC10, identified by BioID, to the alveolin network and intercalated between the SPMTs. Parasites conditionally depleted in AC9 or AC10 replicate normally but are defective in microneme secretion and fail to invade and egress from infected cells. Electron microscopy revealed that the mature parasite mutants are conoidless, while U-ExM highlighted the disorganization of the SPMTs which likely results in the catastrophic loss of APR and conoid.
doi:10.7554/elife.56635 fatcat:oub2cx23xzbvpmowjwxsqkvli4