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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> tubulin at lysine 40 (K40) by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> -acetyltransferase ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> 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 <i>Plasmodium</i> species and <i>Toxoplasma gondii</i>, both of which possess unusually stable subpellicular microtubules, a set of cytoskeletal filaments underlying the parasite's inner membrane complex. Interestingly, while <i>Toxoplasma gondii</i> and human-infecting <i>Plasmodium</i> species retain both K40 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> TAT, rodent-infecting <i>Plasmodium</i> species have lost <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> TAT, and K40 has been replaced by glutamine (Q40), a residue that can mimic acetylated lysine.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 <i>Plasmodium berghei</i> and <i>Toxoplasma gondii</i>. In <i>Plasmodium berghei</i>, introduction of a Q40K mutation in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> 1 tubulin did not affect parasite development or infectivity, suggesting that the absence of K40 acetylation is not detrimental. In <i>Toxoplasma gondii</i>, we confirmed that <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> TAT is responsible for microtubule acetylation but, contrary to previous reports, its deletion had no impact on parasite growth <i>in vitro</i>. 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.