Remodeling of sporozoite microtubules during Plasmodium liver stage development

Microtubules are essential components of the eukaryotic cytoskeleton, controlling cell shape, intracellular organization, and cell division. During the Plasmodium liver stage, parasites undergo exceptionally rapid nuclear replication, yet the organization and dynamics of their microtubule cytoskeleton remain poorly understood. Here, using expansion microscopy, live-cell imaging, and tubulin post-translational modification (PTM)-specific antibodies, we characterize microtubule organization throughout Plasmodium berghei liver stage development. We identified a prominent liver stage parasite microtubule bundle (LSPMB) that appears to originate from the sporozoite subpellicular microtubules. The LSPMB progressively shrinks during liver stage development and, in contrast to sporozoite subpellicular microtubules, becomes sensitive to microtubule depolymerization, revealing extensive remodeling of the parasite microtubule cytoskeleton. LSPMB filaments transiently associate with hemi-spindle poles during schizogony, suggesting that this pre-existing microtubule network may contribute to microtubule organization during nuclear replication. We further identify developmentally regulated changes in antibody signals associated with tubulin polyglutamylation and tyrosination and detect the microtubule plus-end-binding protein EB1 on both the LSPMB and hemi-spindles. Mutational analysis further revealed an important contribution of the α1-tubulin C-terminal region to parasite development: alteration of selected residues impaired liver stage growth, whereas deletion of the entire C-terminal tail severely compromised sporozoite motility and salivary gland colonization. Together, our findings reveal extensive remodeling of the Plasmodium microtubule cytoskeleton during the transition from the invasive sporozoite to the replicative liver stage and identify the α1-tubulin C-terminal region as an important regulator of parasite development and transmission.