Equipe Labellisée La Ligue, CGM, CNRS FRE3144, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, Univ Paris-Sud, Orsay F-91405, France.
Nucleic Acids Res. 2011 Mar;39(6):2221-33. doi: 10.1093/nar/gkq898. Epub 2010 Nov 13.
Eukaryotic and archaeal DRG factors are highly conserved proteins with characteristic GTPase motifs. This suggests their implication in a central biological process, which has so far escaped detection. We show here that the two Saccharomyces cerevisiae DRGs form distinct complexes, RBG1 and RBG2, and that the former co-fractionate with translating ribosomes. A genetic screen for triple synthetic interaction demonstrates that yeast DRGs have redundant function with Slh1, a putative RNA helicase also associating with translating ribosomes. Translation and cell growth are severely impaired in a triple mutant lacking both yeast DRGs and Slh1, but not in double mutants. This new genetic assay allowed us to characterize the roles of conserved motifs present in these proteins for efficient translation and/or association with ribosomes. Altogether, our results demonstrate for the first time a direct role of the highly conserved DRG factors in translation and indicate that this function is redundantly shared by three factors. Furthermore, our data suggest that important cellular processes are highly buffered against external perturbation and, consequently, that redundantly acting factors may escape detection in current high-throughput binary genetic interaction screens.
真核生物和古菌 DRG 因子是高度保守的蛋白质，具有特征性的 GTPase 基序。这表明它们参与了一个中心的生物学过程，而这个过程迄今尚未被发现。我们在这里表明，两种酿酒酵母的 DRG 形成不同的复合物，RBG1 和 RBG2，前者与正在翻译的核糖体共分离。三重合成相互作用的遗传筛选表明，酵母 DRG 与 Slh1 具有冗余功能，Slh1 是一种假定的 RNA 解旋酶，也与正在翻译的核糖体相关联。缺乏酵母 DRG 和 Slh1 的三突变体在翻译和细胞生长方面受到严重损害，但双突变体没有。这种新的遗传测定方法使我们能够描述这些蛋白质中存在的保守基序在有效翻译和/或与核糖体结合中的作用。总的来说，我们的结果首次证明了高度保守的 DRG 因子在翻译中的直接作用，并表明该功能由三个因子冗余共享。此外，我们的数据表明，重要的细胞过程对外部干扰具有高度缓冲作用，因此，在当前的高通量二进制遗传相互作用筛选中，冗余作用的因子可能会被遗漏。
