In bacteria, ribosomal protein bL12 forms the prominent stalk structure on the ribosome and binds to multiple, distinct translational GTPase factors during the sequential steps of translation. Using a genetic selection in E. coli for altered readthrough of UGA stop codons, we have isolated seven different mutations affecting the C-terminal domain of the protein that forms the interaction surface with translation factors. Analysis of these altered proteins, along with four additional alterations previously shown to affect IF2-ribosome interactions, indicates that multiple steps of translation are affected, consistent with bL12’s interaction with multiple factors. Surprisingly, deletion of the release factor GTPase, RF3, has relatively little effect on bL12-promoted stop codon readthrough, suggesting that other steps in termination are also influenced by bL12.

在细菌中，核糖体蛋白 bL12 在核糖体上形成突出的茎结构，并在翻译的连续步骤中与多个不同的翻译 GTPase 因子结合。在大肠杆菌中使用遗传选择为了改变 UGA 终止密码子的通读，我们分离了七种不同的突变，这些突变影响了与翻译因子形成相互作用表面的蛋白质的 C 端结构域。对这些改变的蛋白质的分析，以及先前显示出影响 IF2-核糖体相互作用的四个额外改变，表明翻译的多个步骤受到影响，与 bL12 与多种因素的相互作用一致。令人惊讶的是，释放因子 GTPase RF3 的缺失对 bL12 促进的终止密码子通读的影响相对较小，这表明终止中的其他步骤也受 bL12 的影响。