Shimanovskaya Ekaterina, Qiao Renping, Lesigang Johannes, Dong Gang
Max F. Perutz Laboratories; Medical University of Vienna; Vienna, Austria.
Worm. 2013 Jul 1;2(3):e25214. doi: 10.4161/worm.25214. Epub 2013 May 31.
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.
中心粒是一种基于微管的保守细胞器，对中心体形成和纤毛生物发生至关重要。它具有独特的九重对称性，其组装由至少五种组成蛋白（SPD-2、ZYG-1、SAS-5、SAS-6和SAS-4）控制，这些蛋白按层次顺序募集。最近发表的关于SAS-6 N端结构域的结构研究极大地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端头基团之间的弱相互作用如何驱动闭环状结构的组装，以及在中心粒复制过程中是什么决定了多个环彼此堆叠。我们最近报道，SAS-5通过其C端结构域（CTD，第391-404位氨基酸）特异性结合SAS-6中央卷曲螺旋的一个非常狭窄的区域。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，SAS-5 N端结构域（NTD，第1-260位氨基酸）形成四聚体。具体而言，我们发现四聚体由SAS-5的第82-260位氨基酸形成，而第1-81位氨基酸是内在无序的。综合这些结果，我们提出了一个SAS-5介导的多层中心管结构组装的工作模型。
