Sinclair-Davis Amy N, McAllaster Michael R, de Graffenried Christopher L
Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA.
Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA
J Cell Sci. 2017 Nov 15;130(22):3918-3932. doi: 10.1242/jcs.207209. Epub 2017 Oct 9.
The parasite is highly polarized, including a flagellum that is attached along the cell surface by the flagellum attachment zone (FAZ). During cell division, the new FAZ positions the cleavage furrow, which ingresses from the anterior tip of the cell towards the posterior. We recently identified TOEFAZ1 (for 'Tip of the Extending FAZ protein 1') as an essential protein in trypanosome cytokinesis. Here, we analyzed the localization and function of TOEFAZ1 domains by performing overexpression and RNAi complementation experiments. TOEFAZ1 comprises three domains with separable functions: an N-terminal α-helical domain that may be involved in FAZ recruitment, a central intrinsically disordered domain that keeps the morphogenic kinase TbPLK at the new FAZ tip, and a C-terminal zinc finger domain necessary for TOEFAZ1 oligomerization. Both the N-terminal and C-terminal domains are essential for TOEFAZ1 function, but TbPLK retention at the FAZ is not necessary for cytokinesis. The feasibility of alternative cytokinetic pathways that do not employ TOEFAZ1 are also assessed. Our results show that TOEFAZ1 is a multimeric scaffold for recruiting proteins that control the timing and location of cleavage furrow ingression.
该寄生虫高度极化，包括一条鞭毛，其通过鞭毛附着区（FAZ）沿细胞表面附着。在细胞分裂过程中，新的FAZ定位分裂沟，分裂沟从细胞前端向后方侵入。我们最近鉴定出TOEFAZ1（“延伸的FAZ蛋白1的尖端”）是锥虫胞质分裂中的一种必需蛋白。在这里，我们通过进行过表达和RNAi互补实验分析了TOEFAZ1结构域的定位和功能。TOEFAZ1包含三个具有可分离功能的结构域：一个可能参与FAZ募集的N端α螺旋结构域、一个将形态发生激酶TbPLK保持在新FAZ尖端的中央内在无序结构域，以及一个TOEFAZ1寡聚化所必需的C端锌指结构域。N端和C端结构域对TOEFAZ1功能均至关重要，但TbPLK保留在FAZ对胞质分裂并非必需。我们还评估了不使用TOEFAZ1的替代胞质分裂途径的可行性。我们的结果表明，TOEFAZ1是一种多聚体支架，用于募集控制分裂沟侵入时间和位置的蛋白质。
