Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, Göttingen, Germany.
EMBO Rep. 2010 Mar;11(3):214-9. doi: 10.1038/embor.2009.272. Epub 2010 Jan 8.
The iron-sulphur (Fe-S)-containing RNase L inhibitor (Rli1) is involved in ribosomal subunit maturation, transport of both ribosomal subunits to the cytoplasm, and translation initiation through interaction with the eukaryotic initiation factor 3 (eIF3) complex. Here, we present a new function for Rli1 in translation termination. Through co-immunoprecipitation experiments, we show that Rli1 interacts physically with the translation termination factors eukaryotic release factor 1 (eRF1)/Sup45 and eRF3/Sup35 in Saccharomyces cerevisiae. Genetic interactions were uncovered between a strain depleted for Rli1 and sup35-21 or sup45-2. Furthermore, we show that downregulation of RLI1 expression leads to defects in the recognition of a stop codon, as seen in mutants of other termination factors. By contrast, RLI1 overexpression partly suppresses the read-through defects in sup45-2. Interestingly, we find that although the Fe-S cluster is not required for the interaction of Rli1 with eRF1 or its other interacting partner, Hcr1, from the initiation complex eIF3, it is required for its activity in translation termination; an Fe-S cluster mutant of RLI1 cannot suppress the read-through defects of sup45-2.
含铁硫 (Fe-S) 的核糖核酸酶 L 抑制剂 (Rli1) 参与核糖体亚基成熟、核糖体亚基向细胞质的转运以及通过与真核起始因子 3 (eIF3) 复合物相互作用的翻译起始。在这里，我们提出了 Rli1 在翻译终止中的一个新功能。通过共免疫沉淀实验，我们表明 Rli1 在酿酒酵母中与翻译终止因子真核释放因子 1 (eRF1)/Sup45 和 eRF3/Sup35 物理相互作用。在耗尽 Rli1 的菌株与 sup35-21 或 sup45-2 之间发现了遗传相互作用。此外，我们表明 RLI1 表达下调会导致终止因子突变体中观察到的终止密码子识别缺陷。相比之下，RLI1 的过表达部分抑制了 sup45-2 的通读缺陷。有趣的是，我们发现尽管 Fe-S 簇对于 Rli1 与 eRF1 或其来自起始复合物 eIF3 的其他相互作用伙伴 Hcr1 的相互作用不是必需的，但它对于其在翻译终止中的活性是必需的；RLI1 的 Fe-S 簇突变体不能抑制 sup45-2 的通读缺陷。
