Cytokinetic abscission marks the final stage of cell division, during which the daughter cells physically separate through the generation of new barriers, such as the plasma membrane or cell wall. While the contractile ring plays a central role during cytokinesis in bacteria, fungi and animal cells, the process diverges in Apicomplexa. In Toxoplasma gondii, two daughter cells are formed within the mother cell by endodyogeny. The mechanism by which the progeny cells acquire their plasma membrane during the disassembly of the mother cell, allowing daughter cells to emerge, remains unknown. Here we identify and characterize five T. gondii proteins, including three protein phosphatase 2A subunits, which exhibit a distinct and dynamic localization pattern during parasite division. Individual downregulation of these proteins prevents the accumulation of plasma membrane at the division plane, preventing the completion of cellular abscission. Remarkably, the absence of cytokinetic abscission does not hinder the completion of subsequent division cycles. The resulting progeny are able to egress from the infected cells but fail to glide and invade, except in cases of conjoined twin parasites.

中文翻译：

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刚地弓形虫的细胞动力学脱落受蛋白磷酸酶 2A 和子细胞支架复合物控制。


细胞动力学脱落标志着细胞分裂的最后阶段，在此期间，子细胞通过产生新的屏障（如质膜或细胞壁）进行物理分离。虽然收缩环在细菌、真菌和动物细胞的胞质分裂过程中起着核心作用，但在 Apicomplexa 中，该过程有所不同。在刚地弓形虫中，两个子细胞通过内生性在母细胞内形成。后代细胞在母细胞分解过程中获得质膜，从而出现子细胞的机制仍然未知。在这里，我们鉴定并表征了 5 种刚地弓形虫蛋白，包括 3 种蛋白磷酸酶 2A 亚基，它们在寄生虫分裂过程中表现出独特和动态的定位模式。这些蛋白质的个体下调会阻止质膜在分裂平面的积累，从而阻止细胞脱落的完成。值得注意的是，细胞动力学脱落的缺失并不妨碍后续分裂周期的完成。所得的后代能够从受感染的细胞中排出，但无法滑行和侵入，除非是连体双胞胎寄生虫。