Cell cycle-regulated transcription factor AP2XII-9 is a key activator for asexual division and apicoplast inheritance in <i>Toxoplasma gondii</i> tachyzoite

The intracellular apicoplast parasite <i>Toxoplasma gondii</i> poses a great threat to the public health. The acute infection of <i>T. gondii</i> tachyzoites relies on efficient invasion by forming a moving junction structure and also fast replication by highly regulated endodyogeny. This study shows that an ApiAP2 transcription factor, TgAP2XII-9, acts as an activator for the S/M-phase gene expression, including genes related to daughter buds and moving junction formation. Loss of TgAP2XII-9 results in significant growth defects and disorders in endodyogeny and apicoplast inheritance of the parasites. Our results provide valuable insights into the transcriptional regulation of the parasite cell cycle and invading machinery in <i>T. gondii</i>.