Toxoplasma gondii AP2XII-2 contributes to proper progression through s-phase of the cell cycle

Sandeep Srivastava, Michael W. White, William J. Sullivan

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Toxoplasma gondii is a protozoan parasite that causes lifelong chronic infection that can reactivate in immunocompromised individuals. Upon infection, the replicative stage (tachyzoite) converts into a latent tissue cyst stage (bradyzoite). Like other apicomplexans, T. gondii possesses an extensive lineage of proteins called ApiAP2s that contain DNA-binding domains first characterized in plants. The function of most ApiAP2s is unknown. We previously found that AP2IX-4 is a cell cycleregulated ApiAP2 expressed only in dividing parasites as a putative transcriptional repressor. In this study, we purified proteins interacting with AP2IX-4, finding it to be a component of the recently characterized microrchidia (MORC) transcriptional repressor complex. We further analyzed AP2XII-2, another cell cycle-regulated factor that associates with AP2IX-4. We monitored parallel expression of AP2IX-4 and AP2XII-2 proteins in tachyzoites, detecting peak expression during S/M phase. Unlike AP2IX-4, which is dispensable in tachyzoites, loss of AP2XII-2 resulted in a slowed tachyzoite growth due to a delay in S-phase progression. We also found that AP2XII-2 depletion increased the frequency of bradyzoite differentiation in vitro. These results suggest that multiple AP2 factors collaborate to ensure proper cell cycle progression and tissue cyst formation in T. gondii.

Original languageEnglish (US)
Article numbere00542
Issue number5
StatePublished - Sep 1 2020


  • Apicomplexa
  • Cell cycle
  • Chromatin
  • Differentiation
  • Parasites
  • Toxoplasma
  • Transcription

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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