Sperm flagellar protein 1 (Spef1, also known as CLAMP) is a microtubule-associated protein involved in various microtubule-related functions from ciliary motility to polarized cell movement and planar cell polarity. In Trypanosoma brucei, the causative agent of trypanosomiasis, a single Spef1 ortholog (TbSpef1) is associated with a microtubule quartet (MtQ), which is in close association with several single-copied organelles and is required for their coordinated biogenesis during the cell cycle. Here, we investigated the interaction network of TbSpef1 using BioID, a proximity-dependent protein-protein interaction screening method. Characterization of selected candidates provided a molecular description of TbSpef1-MtQ interactions with nearby cytoskeletal structures. Of particular interest, we identified a new basal body protein TbSAF1, which is required for TbSpef1-MtQ anchorage to the basal bodies. The results demonstrate that MtQ-basal body anchorage is critical for the spatial organization of cytoskeletal organelles, as well as the morphology of the membrane-bound flagellar pocket where endocytosis takes place in this parasite.

中文翻译：

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布鲁氏锥虫基体的微管四方基锚定需要基体蛋白TbSAF1。

精子鞭毛蛋白1（Spef1，也称为CLAMP）是一种微管相关蛋白，涉及从睫毛运动到极化细胞运动和平面细胞极性的各种微管相关功能。在布鲁氏锥虫，是锥虫病的病原体，一个单一的Spef1直系同源物（TbSpef1）与一个微管四重奏（MtQ）相关，该四重奏与几个单复制的细胞器密切相关，并且是它们在细胞周期中协调生物发生所必需的。在这里，我们使用BioID（一种邻近依赖性蛋白-蛋白相互作用筛选方法）研究了TbSpef1的相互作用网络。所选候选物的表征提供了TbSpef1-MtQ与附近细胞骨架结构相互作用的分子描述。特别感兴趣的是，我们鉴定了一种新的基体蛋白TbSAF1，这是将TbSpef1-MtQ锚定在基体上所必需的。结果表明，MtQ基体的锚固对于细胞骨架细胞器的空间组织至关重要，