The Native 3D Organization of Bacterial Polysomes
The Native 3D Organization of Bacterial Polysomes
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DOI：
10.1016/j.cell.2008.11.016
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发表时间：
2009-01-23
期刊：
影响因子：
64.5
通讯作者：
Baumeister, Wolfgang
中科院分区：
文献类型：
--
作者：
Brandt, Florian;Etchells, Stephanie A.;Baumeister, Wolfgang
最近的进展已经导致深入了解细菌核糖体的结构，但很少有人知道的核糖体的3D组织的背景下，翻译的多核糖体。我们采用冷冻电子断层扫描和模板匹配的方法来绘制玻璃化细菌翻译提取物和活性大肠杆菌裂解物中的70S核糖体。coli原生质球。在这些制剂中，观察到多聚核糖体排列，其中相邻的核糖体密集堆积并表现出优选的取向。对多核糖体特征实例的分析揭示了核糖体沿着mRNA踪迹的交错或假螺旋组织，转录物被隔离在内部，tRNA入口位点是可接近的，而多肽出口位点面向胞质溶胶。拉长新生多肽链的建模表明，这种安排使相邻核糖体上新生链之间的距离最大化，从而降低了分子间相互作用的可能性，这种相互作用会引起聚集并限制生产性折叠。
Recent advances have led to insights into the structure of the bacterial ribosome, but little is known about the 3D organization of ribosomes in the context of translating polysomes. We employed cryoelectron tomography and a template-matching approach to map 70S ribosomes in vitrified bacterial translation extracts and in lysates of active E. coli spheroplasts. In these preparations, polysomal arrangements were observed in which neighboring ribosomes are densely packed and exhibit preferred orientations. Analysis of characteristic examples of polysomes reveals a staggered or pseudohelical organization of ribosomes along the mRNA trace, with the transcript being sequestered on the inside, the tRNA entrance sites being accessible, and the polypeptide exit sites facing the cytosol. Modeling of elongating nascent polypeptide chains suggests that this arrangement maximizes the distance between nascent chains on adjacent ribosomes, thereby reducing the probability of intermolecular interactions that would give rise to aggregation and limit productive folding.