From the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030 and.
the Max F. Perutz Laboratories, Vienna Bio-center, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria.
J Biol Chem. 2018 Jun 1;293(22):8508-8520. doi: 10.1074/jbc.RA118.002106. Epub 2018 Apr 17.
causes sleeping sickness in humans and nagana in cattle in sub-Saharan Africa and alternates between its mammalian hosts and its insect vector, the tsetse fly. uses a flagellum for motility, cell division, and cell-cell communication. Proper positioning and attachment of the newly assembled flagellum rely on the faithful duplication and segregation of flagellum-associated cytoskeletal structures. These processes are regulated by the polo-like kinase homolog TbPLK, whose activity and abundance are under stringent control to ensure spatiotemporally regulated phosphorylation of its substrates. However, it remains unclear whether a protein phosphatase that counteracts TbPLK activity is also involved in this regulation. Here, we report that a putative kinetoplastid-specific protein phosphatase, named KPP1, has essential roles in regulating flagellum positioning and attachment in KPP1 localized to multiple flagellum-associated cytoskeletal structures and co-localized with TbPLK in several cytoskeletal structures at different cell-cycle stages. KPP1 depletion abolished basal body segregation, inhibited the duplication of the centrin arm and the hook complex of the bilobe structure, and disrupted the elongation of the flagellum attachment zone, leading to flagellum misplacement and detachment and cytokinesis arrest. Importantly, KPP1-depleted cells lacked dephosphorylation of TbCentrin2, a TbPLK substrate, at late cell-cycle stages. Together, these results suggest that KPP1-mediated protein dephosphorylation regulates the duplication and segregation of flagellum-associated cytoskeletal structures, thereby promoting flagellum positioning and attachment. These findings highlight the requirement of reversible protein phosphorylation, mediated by TbPLK and KPP1, in regulating flagellum inheritance in .
导致人类昏睡病和牛纳格病在撒哈拉以南非洲，并且在其哺乳动物宿主和其昆虫媒介，采采蝇之间交替。 使用鞭毛进行运动，细胞分裂和细胞间通讯。 新组装的鞭毛的正确定位和附着依赖于鞭毛相关细胞骨架结构的忠实复制和分离。 这些过程受 polo 样激酶同源物 TbPLK 调节，其活性和丰度受到严格控制，以确保其底物的时空调节磷酸化。 然而，尚不清楚是否存在一种与 TbPLK 活性相反的蛋白磷酸酶也参与这种调节。 在这里，我们报告一种假定的动基体特异性蛋白磷酸酶，命名为 KPP1，在调节鞭毛定位和附着中具有重要作用。 在 KPP1 中定位到多个鞭毛相关细胞骨架结构，并在不同细胞周期阶段的几个细胞骨架结构中与 TbPLK 共定位。 KPP1 耗尽消除了基体分离，抑制了中心粒臂的复制和双叶结构的钩复合体，并破坏了鞭毛附着区的伸长，导致鞭毛错位和脱离以及胞质分裂停滞。 重要的是，KPP1 耗尽的细胞在晚期细胞周期阶段缺乏 TbCentrin2 的去磷酸化，这是 TbPLK 的底物。 总之，这些结果表明 KPP1 介导的蛋白去磷酸化调节鞭毛相关细胞骨架结构的复制和分离，从而促进鞭毛的定位和附着。 这些发现强调了可逆蛋白磷酸化的要求，由 TbPLK 和 KPP1 介导，在调节 中的鞭毛遗传。
