de Smit M H, van Duin J
Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, The Netherlands.
J Mol Biol. 1994 Nov 25;244(2):144-50. doi: 10.1006/jmbi.1994.1714.
Translational efficiency in Escherichia coli is strongly controlled by the secondary structure of the mRNA in the translational initiation region. We have previously shown that protein production from the coat-protein gene of RNA bacteriophage MS2 is directly related to the fraction of mRNA molecules in which the ribosome binding site is unfolded. This fraction is dictated by the free energy (delta Gf0) of the local secondary structure. We now present a similar analysis of published data on four other ribosome binding sites. The results conform quantitatively to the same relationship as found for the MS2 coat-protein gene. The efficiency of translation is determined by the overall stability of the structure at the ribosome binding site, whether the initiation codon itself is base-paired or not. Structures weaker than -6 kcal/mol usually do not reduce translational efficiency. Below this threshold, all systems show a tenfold decrease in expression for every -1.4 kcal/mol, as predicted from theory.
大肠杆菌中的翻译效率受到翻译起始区域mRNA二级结构的强烈调控。我们之前已经表明，RNA噬菌体MS2外壳蛋白基因的蛋白质产生与核糖体结合位点未折叠的mRNA分子比例直接相关。这个比例由局部二级结构的自由能（ΔGf0）决定。我们现在对其他四个核糖体结合位点的已发表数据进行了类似分析。结果在定量上符合与MS2外壳蛋白基因相同的关系。翻译效率由核糖体结合位点结构的整体稳定性决定，无论起始密码子本身是否碱基配对。弱于-6千卡/摩尔的结构通常不会降低翻译效率。低于这个阈值，所有系统的表达量每降低-1.4千卡/摩尔就会下降10倍，正如理论预测的那样。
