Expansion Microscopy provides new insights into the cytoskeleton of malaria parasites including the conservation of a conoid

Abstract

AbstractMalaria is caused by unicellular Plasmodium parasites. Plasmodium relies on diverse microtubule cytoskeletal structures for its reproduction, multiplication or dissemination. Due to the small size of this parasite, its cytoskeleton has been primarily observable by electron microscopy. Here, we demonstrate that the nanoscale cytoskeleton organization is within reach using ultrastructure expansion microscopy (U-ExM). In developing microgametocytes, U-ExM allows to monitor the dynamic assembly of axonemes and concomitant tubulin polyglutamylation in whole cells. In the invasive merozoite and ookinete forms, U-ExM unveils the subpellicular microtubule arrays that confer cell rigidity. In ookinete, we additionally identify an apical tubulin ring above the subpellicular microtubules that colocalises with markers of the conoid in related Apicomplexa parasites. This microtubule structure was presumed to be lost in Plasmodium despite its crucial role in both motility and invasion in most apicomplexans. Here, U-ExM reveals that a divergent and reduced form of the conoid is actually conserved in the Plasmodium genus.