Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA.
Mol Cell. 2010 Jul 30;39(2):196-208. doi: 10.1016/j.molcel.2010.06.018.
In eukaryotic cells the final maturation of ribosomes occurs in the cytoplasm, where trans-acting factors are removed and critical ribosomal proteins are added for functionality. Here, we have carried out a comprehensive analysis of cytoplasmic maturation, ordering the known steps into a coherent pathway. Maturation is initiated by the ATPase Drg1. Downstream, assembly of the ribosome stalk is essential for the release of Tif6. The stalk recruits GTPases during translation. Because the GTPase Efl1, which is required for the release of Tif6, resembles the translation elongation factor eEF2, we suggest that assembly of the stalk recruits Efl1, triggering a step in 60S biogenesis that mimics aspects of translocation. Efl1 could thereby provide a mechanism to functionally check the nascent subunit. Finally, the release of Tif6 is a prerequisite for the release of the nuclear export adaptor Nmd3. Establishing this pathway provides an important conceptual framework for understanding ribosome maturation.
在真核细胞中，核糖体的最终成熟发生在细胞质中，在此过程中，反式作用因子被去除，并添加关键的核糖体蛋白以实现其功能。在这里，我们对细胞质成熟过程进行了全面分析，将已知的步骤有序地排列成一个连贯的途径。成熟过程由 ATP 酶 Drg1 启动。接下来，核糖体柄的组装对于 Tif6 的释放是必不可少的。该柄在翻译过程中招募 GTP 酶。由于释放 Tif6 所需的 GTP 酶 Efl1 类似于翻译延伸因子 eEF2，我们推测柄的组装会招募 Efl1，从而触发 60S 生物发生的一个步骤，该步骤模拟了转位的某些方面。Efl1 因此可以提供一种机制来对新生亚基进行功能检查。最后，Tif6 的释放是核输出适配器 Nmd3 释放的前提条件。建立这个途径为理解核糖体成熟过程提供了一个重要的概念框架。
