纤毛或真核鞭毛的运动由轴突动力蛋白提供动力,在被运输到睫状轴突上并组装之前,通过称为动力蛋白臂组装因子(DNAAFs)的蛋白质在细胞质中预组装。这里,我们描述了WDR92在衣藻中的功能。WDR92,一种细胞质蛋白的缺失,在通过DNA插入诱变产生的突变体wdr92中,导致无胶细胞或具有短毛或短鞭毛的细胞,轴突动力蛋白臂的消失,细胞质中动力蛋白臂重链的减少,表明WDR92是DNAAF。WDR92的免疫沉淀,然后通过质谱鉴定了内动力蛋白臂重链和多个DNAAF,包括RuvBL1,RPAP3,MOT48,ODA7和DYX1C。含PIH1结构域的蛋白质MOT48与RuvBL1/2和RPAP3形成R2TP样复合物,而PF13是另一种在动力蛋白预组装中具有功能的含PIH1结构域的蛋白质,没有。有趣的是,第三个含PIH1结构域的蛋白TWI1与鞭毛运动无关.WDR92与R2TP样复合物和其他鉴定的DNNAF物理相互作用。我们的数据表明,WDR92与HSP90共伴侣R2TP样复合物以及在动力蛋白预组装中连接其他DNAAFs相关。
The motility of cilia or eukaryotic flagella is powered by the axonemal dyneins, which are preassembled in the cytoplasm by proteins termed dynein arm assembly factors (DNAAFs) before being transported to and assembled on the ciliary axoneme. Here, we characterize the function of WDR92 in Chlamydomonas. Loss of WDR92, a cytoplasmic protein, in a mutant wdr92 generated by DNA insertional mutagenesis resulted in aflagellate cells or cells with stumpy or short flagella, disappearance of axonemal dynein arms, and diminishment of dynein arm heavy chains in the cytoplasm, suggesting that WDR92 is a DNAAF. Immunoprecipitation of WDR92 followed by mass spectrometry identified inner dynein arm heavy chains and multiple DNAAFs including RuvBL1, RPAP3, MOT48, ODA7, and DYX1C. The PIH1 domain-containing protein MOT48 formed a R2TP-like complex with RuvBL1/2 and RPAP3, while PF13, another PIH1 domain-containing protein with function in dynein preassembly, did not. Interestingly, the third PIH1 domain-containing protein TWI1 was not related to flagellar motility. WDR92 physically interacted with the R2TP-like complex and the other identified DNNAFs. Our data suggest that WDR92 functions in association with the HSP90 co-chaperone R2TP-like complex as well as linking other DNAAFs in dynein preassembly.