Luminal acetylation of microtubules is not essential for Plasmodium berghei and Toxoplasma gondii survival.

Post-translational modifications of microtubules regulate their stability and dynamics. Acetylation of α tubulin at lysine 40 (K40) by α -acetyltransferase ( α TAT) occurs on the luminal side of microtubules, stabilizes their structure, and plays essential roles in various cellular processes across eukaryotes. Apicomplexan parasites include the malaria-causing Plasmodium species and Toxoplasma gondii, both of which possess unusually stable subpellicular microtubules, a set of cytoskeletal filaments underlying the parasite's inner membrane complex. Interestingly, while Toxoplasma gondii and human-infecting Plasmodium species retain both K40 and α TAT, rodent-infecting Plasmodium species have lost α TAT, and K40 has been replaced by glutamine (Q40), a residue that can mimic acetylated lysine. Here, we investigate the role of microtubule acetylation in apicomplexan parasites by generating and characterizing genetic mutants in Plasmodium berghei and Toxoplasma gondii. In Plasmodium berghei, introduction of a Q40K mutation in α 1 tubulin did not affect parasite development or infectivity, suggesting that the absence of K40 acetylation is not detrimental. In Toxoplasma gondii, we confirmed that α TAT is responsible for microtubule acetylation but, contrary to previous reports, its deletion had no impact on parasite growth in vitro. Together, these results indicate that luminal K40 acetylation is not essential for microtubule function in either species, pointing to functional redundancy and highlighting the plasticity of cytoskeletal regulation in apicomplexan parasites.