Myasnikov Alexander G, Simonetti Angelita, Marzi Stefano, Klaholz Bruno P
IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Department of Structural Biology and Genomics, Illkirch F-67404, France.
Curr Opin Struct Biol. 2009 Jun;19(3):300-9. doi: 10.1016/j.sbi.2009.04.010. Epub 2009 Jun 1.
Translation initiation is the rate-limiting and most complexly regulated step of protein synthesis in prokaryotes and eukaryotes. In the last few years, cryo-electron microscopy has provided several novel insights into the universal process of translation initiation. Structures of prokaryotic 30S and 70S ribosomal initiation complexes with initiator transfer RNA (tRNA), messenger RNA (mRNA), and initiation factors have recently revealed the mechanism of initiator tRNA recruitment to the assembling ribosomal machinery, involving molecular rearrangements of the ribosome and associated factors. First three-dimensional pictures of the particularly complex eukaryotic translation initiation machinery have been obtained, revealing how initiation factors tune the ribosome for recruiting the mRNA. A comparison of the available prokaryotic and eukaryotic structures shows that--besides significant differences--some key ribosomal features are universally conserved.
翻译起始是原核生物和真核生物蛋白质合成中限速且调控最为复杂的步骤。在过去几年里，冷冻电子显微镜对翻译起始这一普遍过程提供了一些新的见解。原核生物30S和70S核糖体起始复合物与起始转运RNA（tRNA）、信使RNA（mRNA）及起始因子的结构最近揭示了起始tRNA募集到组装中的核糖体机制，这涉及核糖体及相关因子的分子重排。现已获得特别复杂的真核生物翻译起始机制的首批三维图像，揭示了起始因子如何调节核糖体以募集mRNA。对现有原核生物和真核生物结构的比较表明，除了显著差异外，一些关键的核糖体特征是普遍保守的。
