Stahl Guillaume, McCarty Gregory P, Farabaugh Philip J
Dept of Biological Sciences and Program in Molecular and Cell Biology, University of Maryland, Baltimore County, Baltimore, MD 21250, USA.
Trends Biochem Sci. 2002 Apr;27(4):178-83. doi: 10.1016/s0968-0004(02)02064-9.
The ribosome is a molecular machine that converts genetic information in the form of RNA, into protein. Recent structural studies reveal a complex set of interactions between the ribosome and its ligands, mRNA and tRNA, that indicate ways in which the ribosome could avoid costly translational errors. Ribosomes must decode each successive codon accurately, and structural data provide a clear indication of how ribosomes limit recruitment of the wrong tRNA (sense errors). In a triplet-based genetic code there are three potential forward reading frames, only one of which encodes the correct protein. Errors in which the ribosome reads a codon out of the normal reading frame (frameshift errors) occur less frequently than sense errors, although it is not clear from structural data how these errors are avoided. Some mRNA sequences, termed programmed-frameshift sites, cause the ribosome to change reading frame. Based on recent work on these sites, this article proposes that the ribosome uses the structure of the codon-anticodon complex formed by the peptidyl-tRNA, especially its wobble interaction, to constrain the incoming aminoacyl-tRNA to the correct reading frame.
核糖体是一种分子机器，它将RNA形式的遗传信息转化为蛋白质。最近的结构研究揭示了核糖体与其配体（mRNA和tRNA）之间一系列复杂的相互作用，这些相互作用表明了核糖体避免代价高昂的翻译错误的方式。核糖体必须准确解码每个连续的密码子，结构数据清楚地表明了核糖体如何限制错误tRNA的招募（错义错误）。在基于三联体的遗传密码中，有三个潜在的正向阅读框，其中只有一个编码正确的蛋白质。核糖体读取正常阅读框之外的密码子的错误（移码错误）比错义错误发生的频率低，尽管从结构数据中尚不清楚如何避免这些错误。一些mRNA序列，称为程序性移码位点，会导致核糖体改变阅读框。基于最近对这些位点的研究，本文提出核糖体利用肽基-tRNA形成的密码子-反密码子复合物的结构，特别是其摆动相互作用，将进入的氨酰-tRNA限制在正确的阅读框内。
