The SAS-5 N-terminal domain is a tetramer, with implications for centriole assembly in C. elegans.
The SAS-5 N-terminal domain is a tetramer, with implications for centriole assembly in C. elegans.
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DOI：
10.4161/worm.25214
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发表时间：
2013-07-01
期刊：
影响因子：
--
通讯作者：
Dong G
中科院分区：
文献类型：
--
作者：
Shimanovskaya E;Qiao R;Lesigang J;Dong G
中心粒是一种保守的微管型细胞器，对中心体的形成和纤毛的发生都是必不可少的。它具有独特的9重对称性，其组装由至少五种组分蛋白（SPD-2，ZYG-1，SAS-5，SAS-6和SAS-4）控制，这些组分蛋白以分级顺序募集。最近发表的SAS-6 N-末端结构域的结构研究大大推进了我们对中心粒组装机制的理解。然而，目前尚不清楚SAS-6 N-末端头基之间的弱相互作用如何驱动闭合环状结构的组装，以及是什么决定了中心粒重复中多个环的堆叠。我们最近报道，SAS-5通过其C-末端结构域（CTD，残基391-404）特异性结合SAS-6中央卷曲螺旋的一个非常窄的区域。在这里，我们通过静态光散射和小角X射线散射进一步证明了SAS-5 N-末端结构域（NTD，残基1-260）形成四聚体。具体而言，我们发现，四聚体是由SAS-5残基82-260，而残基1-81是内在无序的。将这些结果结合在一起，我们提出了一个工作模型，用于SAS-5介导的多层中心管结构的组装。
The centriole is a conserved microtubule-based organelle essential for both centrosome formation and cilium biogenesis. It has a unique 9-fold symmetry and its assembly is governed by at least five component proteins (SPD-2, ZYG-1, SAS-5, SAS-6 and SAS-4), which are recruited in a hierarchical order. Recently published structural studies of the SAS-6 N-terminal domain have greatly advanced our understanding of the mechanisms of centriole assembly. However, it remains unclear how the weak interaction between the SAS-6 N-terminal head groups could drive the assembly of a closed ring-like structure, and what determines the stacking of multiple rings on top one another in centriole duplication. We recently reported that SAS-5 binds specifically to a very narrow region of the SAS-6 central coiled coil through its C-terminal domain (CTD, residues 391–404). Here, we further demonstrate by both static light scattering and small angle X-ray scattering that the SAS-5 N-terminal domain (NTD, residues 1–260) forms a tetramer. Specifically, we found that the tetramer is formed by SAS-5 residues 82–260, whereas residues 1–81 are intrinsically disordered. Taking these results together, we propose a working model for SAS-5-mediated assembly of the multi-layered central tube structure.