The roles of a flagellar HSP40 ensuring rhythmic beating
The roles of a flagellar HSP40 ensuring rhythmic beating
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鞭毛 HSP40 确保有节奏跳动的作用
DOI：
10.1091/mbc.e18-01-0047
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发表时间：
2019
影响因子：
3.3
通讯作者：
Yang P.
中科院分区：
文献类型：
--
作者：
Zhu X;Poghosyan E.;Rezabkova L.;Mehall B.;Sakakibara H.;Hirono M.;Kamiya R.;Ishikawa T.;Yang P.
HSP40被认为是辅伴侣，将客户多肽永久地运送到HSP70进行复性。然而，许多对不同过程至关重要的HSP40偏离了这一范例。为了阐明非典型机制，我们研究了鞭毛中径向辐条(RS)复合体中的HSP40。衣藻中的MRC1转座子破坏了该基因，导致鞭毛干缩。传统的电子显微镜、冷冻电子断层扫描和亚断层图像分析显示，这两个RS物种之间的RSS有各种变化的形态，这是出人意料的。这表明HSP40将RS锁定在一种功能刚性的构象中，促进其与相邻的中央对装置的相互作用，以传递局部变化的机械反馈，从而允许有节奏的跳动。当Hsp40突变体与Hsp40供体细胞融合时，缺失的Hsp40就像缺失的RSS一样，可以从末端到碱基的方向恢复。然而，在没有伴随的RS组装的情况下，修复非常缓慢，这表明Hsp40/RS偶联的鞭毛内运输和组装。生化分析和建模揭示了HSP40‘S的辅伴侣特性。根据我们的数据，我们认为Hsp40在到达鞭毛尖端时伴随着它的客户RS前体。到达后，两者重新折叠，以组装成成熟的配置。HSP40的S在陪伴和结构维护中的作用为其多功能性和鞭毛生物学提供了新的线索。
HSP40s are regarded as cochaperones, perpetually shuttling client polypeptides to HSP70s for refolding. However, many HSP40s that are central for disparate processes diverge from this paradigm. To elucidate the noncanonical mechanisms, we investigated HSP40 in the radial spoke (RS) complex in flagella. Disruption of the gene by the MRC1 transposon inChlamydomonasresulted in jerky flagella. Traditional electron microscopy, cryo-electron tomography, and sub-tomogram analysis revealed RSs of various altered morphologies that, unexpectedly, differed between the two RS species. This indicates that HSP40 locks the RS into a functionally rigid conformation, facilitating its interactions with the adjacent central pair apparatus for transducing locally varied mechanical feedback, which permits rhythmic beating. Missing HSP40, like missing RSs, could be restored in a tip-to-base direction when HSP40 mutants fused with a HSP40 donor cell. However, without concomitant de novo RS assembly, the repair was exceedingly slow, suggesting HSP40/RS-coupled intraflagellar trafficking and assembly. Biochemical analysis and modeling uncovered spoke HSP40’s cochaperone traits. On the basis of our data, we propose that HSP40 accompanies its client RS precursor when traveling to the flagellar tip. Upon arrival, both refold in concert to assemble into the mature configuration. HSP40’s roles in chaperoning and structural maintenance shed new light on its versatility and flagellar biology.