Tammana T V Satish, Sahasrabuddhe Amogh A, Mitra Kalyan, Bajpai Virendra K, Gupta Chhitar M
Division of Molecular and Structural Biology, Central Drug Research Institute, Lucknow 226001, India.
Mol Microbiol. 2008 Nov;70(4):837-52. doi: 10.1111/j.1365-2958.2008.06448.x. Epub 2008 Sep 11.
ADF/cofilins are ubiquitous actin dynamics-regulating proteins that have been mainly implicated in actin-based cell motility. Trypanosomatids, e.g. Leishmania and Trypanosoma, which mediate their motility through flagellum, also contain a putative ADF/cofilin homologue, but its role in flagellar motility remains largely unexplored. We have investigated the role of this protein in assembly and motility of the Leishmania flagellum after knocking out the ADF/cofilin gene by targeted gene replacement. The resultant mutants were completely immotile, short and stumpy, and had reduced flagellar length and severely impaired beat. In addition, the assembly of the paraflagellar rod was lost, vesicle-like structures were seen throughout the length of the flagellum and the state and distribution of actin were altered. However, episomal complementation of the gene restored normal morphology and flagellar function. These results for the first time indicate that the actin dynamics-regulating protein ADF/cofilin plays a critical role in assembly and motility of the eukaryotic flagellum.
ADF/丝切蛋白是普遍存在的肌动蛋白动力学调节蛋白，主要参与基于肌动蛋白的细胞运动。锥虫，如利什曼原虫和锥虫，通过鞭毛介导其运动，也含有一种假定的ADF/丝切蛋白同源物，但其在鞭毛运动中的作用在很大程度上仍未被探索。我们通过靶向基因替换敲除ADF/丝切蛋白基因后，研究了该蛋白在利什曼原虫鞭毛组装和运动中的作用。产生的突变体完全不能运动，短而粗，鞭毛长度缩短，摆动严重受损。此外，副鞭毛杆的组装消失，在鞭毛全长可见囊泡样结构，肌动蛋白的状态和分布发生改变。然而，该基因的附加型互补恢复了正常形态和鞭毛功能。这些结果首次表明，肌动蛋白动力学调节蛋白ADF/丝切蛋白在真核生物鞭毛的组装和运动中起关键作用。
