The centrosome is the main microtubule-organizing center in animal cells. It comprises of two centrioles and the surrounding pericentriolar material. Protein organization at the outer layer of the centriole and outward has been studied extensively; however, an overall picture of the protein architecture at the centriole core has been missing. Here we report a direct view of Drosophila centriolar proteins at ∼50-nm resolution. This reveals a Sas6 ring at the C-terminus, where it overlaps with the C-terminus of Cep135. The ninefold symmetrical pattern of Cep135 is further conveyed through Ana1-Asterless axes that extend past the microtubule wall from between the blades. Ana3 and Rcd4, whose termini are close to Cep135, are arranged in ninefold symmetry that does not match the above axes. During centriole biogenesis, Ana3 and Rcd4 are sequentially loaded on the newly formed centriole and are required for centriole-to-centrosome conversion through recruiting the Cep135-Ana1-Asterless complex. Together, our results provide a spatiotemporal map of the centriole core and implications of how the structure might be built.

中文翻译：

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核心中心架构的超分辨率表征。

中心体是动物细胞中主要的微管组织中心。它由两个中心粒和周围的中心粒物质组成。广泛研究了中心粒外层和向外的蛋白质组织。但是，缺少中心粒蛋白质结构的总体图。在这里，我们报道了果蝇中心蛋白在〜50 nm分辨率下的直接视图。这表明在C末端的Sas6环与Cep135的C末端重叠。Cep135的九重对称模式进一步通过Ana1-Asterless轴传递，该轴从叶片之间延伸超过微管壁。末端接近于Cep135的Ana3和Rcd4呈九重对称排列，与上述轴不匹配。在中心粒生物发生期间，Ana3和Rcd4依次加载到新形成的中心粒上，并通过募集Cep135-Ana1-Asterless复合体将其用于中心粒到中心体的转化。在一起，我们的结果提供了中心核的时空图以及该结构可能如何构建的含义。