The distal central pair segment is structurally specialised and contributes to IFT turnaround and assembly of the tip capping structures in Chlamydomonas flagella

IF 2.4 4区生物学 Q4 CELL BIOLOGY Biology of the Cell Pub Date : 2022-09-13 DOI:10.1111/boc.202200038

Ambra Pratelli, Dalia Corbo, Pietro Lupetti, Caterina Mencarelli

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引用次数: 1

Abstract

Background Information

Cilia and flagella are dynamic organelles whose assembly and maintenance depend on an activetrafficking process known as the IntraFlagellar Transport (IFT), during which trains of IFT protein particles are moved by specific motors and carry flagellar precursors and turnover products along the axoneme. IFT consists of an anterograde (from base to tip) and a retrograde (from tip to base) phase. During IFT turnaround at the flagellar tip, anterograde trains release their cargoes and remodel to form the retrograde trains. Thus, turnaround is crucial for correct IFT. However, current knowledge of its mechanisms is limited.

Results

We show here that in Chlamydomonas flagella the distal ∼200 nm central pair (CP) segment is structurally differentiated for the presence of a ladder-like structure (LLS). During IFT turnaround, the IFT172 subunit dissociates from the IFT- B protein complex and binds to the LLS-containing CP segment, while the IFT-B complex participates in the assembly of the CP capping structures. The IFT scaffolding function played by the LLS-containing CP segment relies on anchoring components other than the CP microtubules, since IFT turnaround occurs also in the CP-devoid pf18 mutant flagella.

Conclusions

During IFT turnaround in Chlamydomonas flagella, i) the LLS and the CP terminal plates act as anchoring platforms for IFT172 and the IFT-B complex, respectively, and ii) during its remodeling, the IFT-B complex contributes to the assembly of the CP capping structures.

Significance

Our results indicate that in full length Chlamydomonas flagella IFT remodeling occurs by a specialized mechanism that involves flagellar tip structures and is distinct from the previously proposed model in which the capability to reverse motility would be intrinsic of IFT train and independent by any other flagellar structure.

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在鞭毛衣藻中，远端中央对段在结构上是专门的，并有助于IFT周转和尖端盖结构的组装

纤毛和鞭毛是动态的细胞器，其组装和维护依赖于一个被称为鞭毛内运输(IFT)的活跃运输过程，在此过程中，IFT蛋白颗粒序列由特定的马达移动，并携带鞭毛前体和沿轴突的周转产物。IFT由顺行期(从基部到尖端)和逆行期(从尖端到基部)组成。在鞭毛尖端的IFT转弯期间，顺行列车释放货物并改造成逆行列车。因此，周转对正确的IFT至关重要。然而，目前对其机制的了解有限。我们在这里发现，鞭毛衣藻远端~ 200 nm的中央对(CP)片段在结构上分化为阶梯状结构(LLS)。在IFT转化过程中，IFT172亚基从IFT-B蛋白复合物中分离并结合到含有lls的CP片段上，而IFT-B复合物则参与CP盖层结构的组装。含有lls的CP片段发挥的IFT支架功能依赖于CP微管以外的锚定成分，因为IFT周转也发生在缺乏CP的pf18突变鞭毛中。结论在鞭毛衣藻的IFT翻转过程中，i) LLS和CP终板分别作为IFT172和IFT- b复合物的锚定平台，ii)在其重塑过程中，IFT- b复合物参与了CP盖层结构的组装。我们的研究结果表明，在全长鞭毛衣藻中，IFT重构是通过一种涉及鞭毛尖端结构的特殊机制发生的，与之前提出的模型不同，该模型认为，逆转运动的能力是IFT序列固有的，与任何其他鞭毛结构无关。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Biology of the Cell 生物-细胞生物学

CiteScore

5.30

自引率

0.00%

发文量

审稿时长

>12 weeks

期刊介绍： The journal publishes original research articles and reviews on all aspects of cellular, molecular and structural biology, developmental biology, cell physiology and evolution. It will publish articles or reviews contributing to the understanding of the elementary biochemical and biophysical principles of live matter organization from the molecular, cellular and tissues scales and organisms. This includes contributions directed towards understanding biochemical and biophysical mechanisms, structure-function relationships with respect to basic cell and tissue functions, development, development/evolution relationship, morphogenesis, stem cell biology, cell biology of disease, plant cell biology, as well as contributions directed toward understanding integrated processes at the organelles, cell and tissue levels. Contributions using approaches such as high resolution imaging, live imaging, quantitative cell biology and integrated biology; as well as those using innovative genetic and epigenetic technologies, ex-vivo tissue engineering, cellular, tissue and integrated functional analysis, and quantitative biology and modeling to demonstrate original biological principles are encouraged.