Shimogawa Michelle M, Jonnalagadda Keya, Hill Kent L
Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, CA, 90095, USA.
California NanoSystems Institute, University of California Los Angeles, Los Angeles, CA, 90095, USA.
bioRxiv. 2024 Jan 20:2024.01.19.576295. doi: 10.1101/2024.01.19.576295.
is a human and animal pathogen that depends on flagellar motility for transmission and infection. The trypanosome flagellum is built around a canonical "9+2" axoneme, containing nine doublet microtubules (DMTs) surrounding two singlet microtubules. Each DMT contains a 13-protofilament A-tubule and a 10-protofilament B-tubule, connected to the A-tubule by a conserved, non-tubulin inner junction (IJ) filament made up of alternating PACRG and FAP20 subunits. Here we investigate FAP20 in procyclic form . A FAP20-NeonGreen fusion protein localized to the axoneme as expected. Surprisingly, FAP20 knockdown led to a catastrophic failure in flagellum assembly and concomitant lethal cell division defect. This differs from other organisms, where FAP20 is required for normal flagellum motility, but generally dispensable for flagellum assembly and viability. Transmission electron microscopy demonstrates failed flagellum assembly in FAP20 mutants is associated with a range of DMT defects and defective assembly of the paraflagellar rod, a lineage-specific flagellum filament that attaches to DMT 4-7 in trypanosomes. Our studies reveal a lineage-specific requirement for FAP20 in trypanosomes, offering insight into adaptations for flagellum stability and motility in these parasites and highlighting pathogen versus host differences that might be considered for therapeutic intervention in trypanosome diseases.
是一种人类和动物病原体，依靠鞭毛运动进行传播和感染。锥虫鞭毛围绕典型的“9+2”轴丝构建，包含围绕两根单微管的九对双微管（DMT）。每个DMT包含一条由13个原纤维组成的A微管和一条由10个原纤维组成的B微管，通过由交替的PACRG和FAP20亚基组成的保守的非微管蛋白内部连接（IJ）细丝与A微管相连。在这里，我们研究前循环形式的FAP20。FAP20-绿色荧光蛋白融合蛋白如预期定位于轴丝。令人惊讶的是，FAP20基因敲低导致鞭毛组装灾难性失败，并伴随致命的细胞分裂缺陷。这与其他生物不同，在其他生物中，FAP20是正常鞭毛运动所必需的，但通常对鞭毛组装和生存力是可有可无的。透射电子显微镜显示，FAP20突变体中鞭毛组装失败与一系列DMT缺陷以及副鞭毛杆的组装缺陷有关，副鞭毛杆是锥虫中附着于DMT 4-7的谱系特异性鞭毛细丝。我们的研究揭示了锥虫对FAP20的谱系特异性需求，为了解这些寄生虫鞭毛稳定性和运动性的适应性提供了见解，并突出了病原体与宿主之间的差异，这些差异可能被考虑用于锥虫病的治疗干预。
