ABSTRACT

Ribosome-associated non-coding RNAs (rancRNAs) have been recognized as an emerging class of regulatory molecules capable of fine-tuning translation in all domains of life. RancRNAs are ideally suited for allowing a swift response to changing environments and are therefore considered pivotal during the first wave of stress adaptation. Previously, we identified an mRNA-derived 18 nucleotides long rancRNA (rancRNA_18) in Saccharomyces cerevisiae that rapidly downregulates protein synthesis during hyperosmotic stress. However, the molecular mechanism of action remained enigmatic. Here, we combine biochemical, genetic, transcriptome-wide and structural evidence, thus revealing rancRNA_18 as global translation inhibitor by targeting the E-site region of the large ribosomal subunit. Ribosomes carrying rancRNA_18 possess decreased affinity for A-site tRNA and impaired structural dynamics. Cumulatively, these discoveries reveal the mode of action of a rancRNA involved in modulating protein biosynthesis at a thus far unequalled precision.

摘要

核糖体相关的非编码 RNA (rancRNA) 已被认为是一类新兴的调节分子，能够在生命的所有领域微调翻译。RancRNA 非常适合对不断变化的环境做出快速反应，因此在第一波压力适应过程中被认为是关键。以前，我们在酿酒酵母中鉴定了一种源自 mRNA 的 18 个核苷酸长的 rancRNA (rancRNA_18)在高渗应激期间迅速下调蛋白质合成。然而，作用的分子机制仍然是神秘的。在这里，我们结合生化、遗传、转录组范围和结构证据，从而通过靶向大核糖体亚基的 E 位点区域揭示 rancRNA_18 作为全局翻译抑制剂。携带 rancRNA_18 的核糖体对 A 位点 tRNA 的亲和力降低，结构动力学受损。累积起来，这些发现揭示了参与以迄今为止无与伦比的精度调节蛋白质生物合成的 rancRNA 的作用方式。