Single Cell RNA-Seq of Toxoplasma gondii AP2X-1 knockout

The life cycles of Toxoplasma gondii involve transitions between disparate host species, requiring these parasites to go through multiple developmental stages, each finely tuned to adapt to the unique environments of these specialized niches. To achieve this, T. gondii has developed a remarkably sophisticated and accurate genetic reprogramming system. However, the underlying regulatory mechanisms of T. gondii transitions between life cycle stages are poorly understood. Here, we characterized an AP2 family transcription factor called AP2X-1, which is expressed during both the tachyzoite and bradyzoite stages. Knockout or depletion of AP2X-1 had significant effect on tachyzoite invasion, replication and led to an increased frequency of tissue cyst formation. As a component of the HDAC3/MORC complex, the knockout of AP2X-1 also leads to the upregulation of bradyzoite and sexual stage-specific genes. CUT&Tag analysis demonstrated a significant overlap between AP2X-1 and HDAC3/MORC targeting the promoters of these genes, suggesting that AP2X-1 recruits HDAC3/MORC to repress sexual commitment. Additionally, the loss of AP2X-1 resulted in drastic attenuation of T. gondii virulence and a decrease in the ability to form brain cyst in vivo. Our findings indicate that AP2X-1 is a key negative regulator mediating of T. gondii sexual development.