Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
Archaea. 2012;2012:260909. doi: 10.1155/2012/260909. Epub 2012 Dec 27.
Nonprotein coding RNA (ncRNA) molecules have been recognized recently as major contributors to regulatory networks in controlling gene expression in a highly efficient manner. These RNAs either originate from their individual transcription units or are processing products from longer precursor RNAs. For example, tRNA-derived fragments (tRFs) have been identified in all domains of life and represent a growing, yet functionally poorly understood, class of ncRNA candidates. Here we present evidence that tRFs from the halophilic archaeon Haloferax volcanii directly bind to ribosomes. In the presented genomic screen of the ribosome-associated RNome, a 26-residue-long fragment originating from the 5' part of valine tRNA was by far the most abundant tRF. The Val-tRF is processed in a stress-dependent manner and was found to primarily target the small ribosomal subunit in vitro and in vivo. As a consequence of ribosome binding, Val-tRF reduces protein synthesis by interfering with peptidyl transferase activity. Therefore this tRF functions as ribosome-bound small ncRNA capable of regulating gene expression in H. volcanii under environmental stress conditions probably by fine tuning the rate of protein production.
非蛋白编码 RNA（ncRNA）分子最近被认为是控制基因表达的调控网络中的主要贡献者，以高效的方式进行调控。这些 RNA 要么来自它们各自的转录单元，要么是来自更长的前体 RNA 的加工产物。例如，tRNA 衍生片段（tRFs）已在所有生命领域中被鉴定出来，并且代表了一个不断增长但功能仍知之甚少的 ncRNA 候选物类别。在这里，我们提供的证据表明，嗜盐古菌 Haloferax volcanii 的 tRFs 直接与核糖体结合。在 presented 基因组筛选的核糖体相关 RNA 组中，一个来自 Val-tRNA 5' 端的 26 个核苷酸长的片段是最丰富的 tRF。Val-tRF 以应激依赖的方式进行加工，并且在体外和体内主要靶向小核糖体亚基。由于与核糖体结合，Val-tRF 通过干扰肽基转移酶活性来降低蛋白质合成。因此，这种 tRF 作为核糖体结合的小 ncRNA 发挥作用，能够在环境应激条件下调节 H. volcanii 中的基因表达，可能通过精细调节蛋白质产生的速度。
