可视化转运信使核糖核酸（tmRNA）进入停滞核糖体的过程。

Visualizing tmRNA entry into a stalled ribosome.

作者信息

Valle Mikel, Gillet Reynald, Kaur Sukhjit, Henne Anke, Ramakrishnan V, Frank Joachim

机构信息

Howard Hughes Medical Institute, Wadsworth Center, Health Research, Inc., Empire State Plaza, Albany, NY 12201-0509, USA.

出版信息

Science. 2003 Apr 4;300(5616):127-30. doi: 10.1126/science.1081798.

DOI:10.1126/science.1081798

PMID:12677067

Abstract

Bacterial ribosomes stalled on defective messenger RNAs (mRNAs) are rescued by tmRNA, an approximately 300-nucleotide-long molecule that functions as both transfer RNA (tRNA) and mRNA. Translation then switches from the defective message to a short open reading frame on tmRNA that tags the defective nascent peptide chain for degradation. However, the mechanism by which tmRNA can enter and move through the ribosome is unknown. We present a cryo-electron microscopy study at approximately 13 to 15 angstroms of the entry of tmRNA into the ribosome. The structure reveals how tmRNA could move through the ribosome despite its complicated topology and also suggests roles for proteins S1 and SmpB in the function of tmRNA.

摘要

停滞在缺陷信使核糖核酸（mRNA）上的细菌核糖体可被转移信使核糖核酸（tmRNA）拯救，tmRNA是一种长度约为300个核苷酸的分子，兼具转运核糖核酸（tRNA）和mRNA的功能。翻译随后从缺陷信使切换到tmRNA上的一个短开放阅读框，该阅读框标记缺陷新生肽链以便降解。然而，tmRNA进入并穿过核糖体的机制尚不清楚。我们展示了一项关于tmRNA进入核糖体的约13至15埃分辨率的冷冻电子显微镜研究。该结构揭示了tmRNA尽管拓扑结构复杂却仍能穿过核糖体的方式，还暗示了蛋白质S1和SmpB在tmRNA功能中的作用。