THE IDENTITY OF THE BASE FOLLOWING THE STOP CODON DETERMINES THE EFFICIENCY OF IN-VIVO TRANSLATIONAL TERMINATION IN ESCHERICHIA-COLI
THE IDENTITY OF THE BASE FOLLOWING THE STOP CODON DETERMINES THE EFFICIENCY OF IN-VIVO TRANSLATIONAL TERMINATION IN ESCHERICHIA-COLI
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DOI：
10.1002/j.1460-2075.1995.tb06985.x
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发表时间：
1995-01-03
期刊：
影响因子：
11.4
通讯作者：
TATE, WP
中科院分区：
文献类型：
--
作者：
POOLE, ES;BROWN, CM;TATE, WP
对超过2000个大肠杆菌基因的统计分析表明，翻译终止密码子后的碱基可能是终止信号的重要特征。在体内终止测定中测试12种可能的“四碱基终止信号”（UAAN、UGAN和UAGN）中的每一种的强度，所述体内终止测定通过其与移码的直接竞争来测量终止效率。终止效率根据终止密码子和第四个碱基而显著变化，范围从80%（UAAU）到7%（UGAC）。对于UAAN和UGAN系列，第四个基本层次是U > G > A，类似于C。大肠杆菌中很少使用的UAG终止密码子显示出与UAAN和UGAN相当的效率，但不同之处在于第四个碱基的等级是G > U，类似于A > C。释放因子选择的速率在UGAN终止信号处变化30倍，对于UAAN和UAGN系列变化10倍;它与在自然终止位点发现不同的UAAN和UGAN信号的频率良好相关。结果表明，终止密码子后的碱基的身份决定在大肠杆菌中的翻译终止的效率。它们还为在高表达基因中使用强UAAU信号和在几个重编码位点出现较弱UGAC信号提供了理论基础。
A statistical analysis of >2000 Escherichia coli genes suggested that the base following the translational stop codon might be an important feature of the signal for termination. The strengths of each of 12 possible 'four base stop signals' (UAAN, UGAN and UAGN) were tested in an in vivo termination assay that measured termination efficiency by its direct competition with frameshifting. Termination efficiencies varied significantly depending on both the stop codon and the fourth base, ranging from 80 (UAAU) to 7% (UGAC). For both the UAAN and UGAN series, the fourth base hierarchy was U > G > A similar to C. UAG stop codons, which are used rarely in E.coli, showed efficiencies comparable with UAAN and UGAN, but differed in that the hierarchy of the fourth base was G > U similar to A > C. The rate of release factor selection varied 30-fold at UGAN stop signals, and 10-fold for both the UAAN and UAGN series; it correlated well with the frequency with which the different UAAN and UGAN signals are found at natural termination sites. The results suggest that the identity of the base following the stop codon determines the efficiency of translational termination in E.coli. They also provide a rationale for the use of the strong UAAU signal in highly expressed genes and for the occurrence of the weaker UGAC signal at several recoding sites.