Cytokinetic Abscission in Toxoplasma gondii is governed by Protein Phosphatase 2A and the Daughter Cell Scaffold Complex

Cytokinetic abscission is the last step of cell division during which the daughter cells physically separate through the generation of barriers in the form of new plasma membrane or cell wall. While the contractile ring is a prominent structure during cytokinesis in bacteria, fungi and animal cells, the mechanism is divergent in Apicomplexa. In Toxoplasma gondii, two daughter cells are formed within the intact mother cell by endodyogeny. The acquisition of plasma membrane at the end of the division cycle occurs by an unknown mechanism, when the mother cell disassembles, and the daughter cells emerge. Here we identified and functionally characterized the essential subunits of a predicted PP2A complex in T. gondii, named PP2A-2. The three subunits PP2A-A2, -B2 and -C2 exhibit a dynamic localization during parasite division. Their individual downregulation prevents the accumulation of plasma membrane at the division plane, resulting in a block of cytokinesis. Remarkably, the absence of cytokinetic abscission does not preclude division cycles and the consecutive progeny is able to successfully egress from the infected cells but fails to glide andinvade new host cells.