The PP2A-2 holoenzyme orchestrates daughter cell emergence during cytokinesis in Toxoplasma gondii

Toxoplasma gondii is a significant pathogen affecting both humans and animals, with clinical symptoms primarily driven by the uncontrolled proliferation of tachyzoites. In this study, we reveal the essential role and functional plasticity of the PP2A-2 holoenzyme in orchestrating daughter cell emergence during tachyzoite division. The holoenzyme, composed of the regulatory subunit TgPR48 (PP2A-B2), the catalytic subunit PP2A-C2, and the scaffolding subunit PP2A-A2, is critical for successful cell division. Depletion of any of these subunits resulted in severe defects in daughter cell emergence and impaired proper cell separation. Phosphoproteomic analysis following PP2A-C2 depletion identified multiple differentially phosphorylated proteins, including potential regulatory substrates DCS1 and DCS2. However, mutating several phosphorylation sites on DCS1 and DCS2 did not significantly alter their function. Interestingly, depletion of DCS1 or DCS2 disrupted TgPR48 localization, while PR48 overexpression partially rescued defects in DCS2-depleted parasites but not in DCS1-depleted parasites. This suggests that PP2A-2 may compensate through additional, yet unidentified, substrates. Our findings highlight the crucial role of PP2A-2–mediated dephosphorylation in T. gondii tachyzoite division and identify potential molecular targets for therapeutic intervention.