Moreira Bernardo P, Fonseca Carol K, Hammarton Tansy C, Baqui Munira M A
Department of Cellular and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto 14049-900, Brazil.
Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
J Cell Sci. 2017 Mar 15;130(6):1179-1193. doi: 10.1242/jcs.194308. Epub 2017 Feb 13.
The flagellum and flagellum attachment zone (FAZ) are important cytoskeletal structures in trypanosomatids, being required for motility, cell division and cell morphogenesis. Trypanosomatid cytoskeletons contain abundant high molecular mass proteins (HMMPs), but many of their biological functions are still unclear. Here, we report the characterization of the giant FAZ protein, FAZ10, in , which, using immunoelectron microscopy, we show localizes to the intermembrane staples in the FAZ intracellular domain. Our data show that FAZ10 is a giant cytoskeletal protein essential for normal growth and morphology in both procyclic and bloodstream parasite life cycle stages, with its depletion leading to defects in cell morphogenesis, flagellum attachment, and kinetoplast and nucleus positioning. We show that the flagellum attachment defects are probably brought about by reduced tethering of the proximal domain of the paraflagellar rod to the FAZ filament. Further, FAZ10 depletion also reduces abundance of FAZ flagellum domain protein, ClpGM6. Moreover, ablation of FAZ10 impaired the timing and placement of the cleavage furrow during cytokinesis, resulting in premature or asymmetrical cell division.
鞭毛和鞭毛附着区（FAZ）是锥虫中的重要细胞骨架结构，对运动、细胞分裂和细胞形态发生至关重要。锥虫的细胞骨架含有丰富的高分子量蛋白质（HMMPs），但其许多生物学功能仍不清楚。在此，我们报道了巨型FAZ蛋白FAZ10在[具体物种未给出]中的特征，利用免疫电子显微镜，我们发现它定位于FAZ细胞内结构域的膜间钉。我们的数据表明，FAZ10是一种巨型细胞骨架蛋白，在前期循环和血流寄生虫生命周期阶段对正常生长和形态至关重要，其缺失会导致细胞形态发生、鞭毛附着以及动质体和细胞核定位缺陷。我们表明，鞭毛附着缺陷可能是由于副鞭毛杆近端结构域与FAZ细丝的连接减少所致。此外，FAZ10的缺失还会降低FAZ鞭毛结构域蛋白ClpGM6的丰度。此外，FAZ10的缺失会损害胞质分裂期间分裂沟的时间和位置，导致过早或不对称的细胞分裂。
