Institute of Molecular and Cell Biology, University of Tartu, Tartu 51010, Estonia.
Nucleic Acids Res. 2019 Jan 10;47(1):406-420. doi: 10.1093/nar/gky1083.
Interactions between subunits in the Saccharomyces cerevisiae ribosome are mediated by universal and eukaryote-specific intersubunit bridges. Universal bridges are positioned close to the ribosomal functional centers, while eukaryote-specific bridges are mainly located on the periphery of the ribosome. Two bridges, eB13 and B6, are formed by the ribosomal protein eL24. The eukaryotic eL24 is composed of an N-terminal domain, a linker region and a C-terminal α-helix. Here, the functions of different domains of eL24 in the S. cerevisiae ribosome were evaluated. The C-terminal domain and the linker region of the eL24 form eukaryote-specific eB13 bridge. Phenotypic characterization of the eL24 deletion mutants indicated that the functional integrity of the eB13 bridge mainly depends on the protein-protein contacts between eL24 and eS6. Further investigation showed importance of the eB13 bridge in the subunit joining in vivo and in vitro. In vitro translation assay demonstrated the role of the eB13 bridge in both initiation and elongation steps of translation. Intriguingly, results of in vitro translation experiment suggest involvement of the N-terminal domain of eL24 in the translation initiation. Therefore, eL24 performs number of tasks required for the optimal ribosome functionality.
酵母核糖体亚基间的相互作用由通用和真核生物特有的亚基间桥介导。通用桥位于核糖体功能中心附近，而真核生物特异性桥主要位于核糖体的外围。两个桥，eB13 和 B6，由核糖体蛋白 eL24 形成。真核生物 eL24 由 N 端结构域、连接区和 C 端α-螺旋组成。在此，评估了 eL24 的不同结构域在酿酒酵母核糖体中的功能。eL24 的 C 端结构域和连接区形成真核生物特异性 eB13 桥。eL24 缺失突变体的表型特征表明，eB13 桥的功能完整性主要取决于 eL24 和 eS6 之间的蛋白-蛋白相互作用。进一步的研究表明，eB13 桥在体内和体外亚基连接中很重要。体外翻译实验证明了 eB13 桥在翻译起始和延伸步骤中的作用。有趣的是，体外翻译实验的结果表明，eL24 的 N 端结构域参与翻译起始。因此，eL24 执行了许多优化核糖体功能所需的任务。
