Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK.
Science. 2012 Mar 16;335(6074):1366-9. doi: 10.1126/science.1217039.
In bacteria, ribosomes stalled at the end of truncated messages are rescued by transfer-messenger RNA (tmRNA), a bifunctional molecule that acts as both a transfer RNA (tRNA) and a messenger RNA (mRNA), and SmpB, a small protein that works in concert with tmRNA. Here, we present the crystal structure of a tmRNA fragment, SmpB and elongation factor Tu bound to the ribosome at 3.2 angstroms resolution. The structure shows how SmpB plays the role of both the anticodon loop of tRNA and portions of mRNA to facilitate decoding in the absence of an mRNA codon in the A site of the ribosome and explains why the tmRNA-SmpB system does not interfere with normal translation.
在细菌中，核糖体在截短消息的末尾停滞，由转移信使 RNA（tmRNA）拯救，tmRNA 是一种具有 tRNA 和 mRNA 双重功能的分子，SmpB 是一种与 tmRNA 协同作用的小蛋白。在这里，我们展示了在 3.2 埃分辨率下与核糖体结合的 tmRNA 片段、SmpB 和延伸因子 Tu 的晶体结构。该结构展示了 SmpB 如何扮演 tRNA 的反密码子环和部分 mRNA 的作用，以促进在核糖体的 A 位没有 mRNA 密码子时的解码，并解释了为什么 tmRNA-SmpB 系统不会干扰正常翻译。
