Petersen C
Institute of Microbiology, University of Copenhagen, Denmark.
J Bacteriol. 1991 Apr;173(7):2167-72. doi: 10.1128/jb.173.7.2167-2172.1991.
The Escherichia coli lacZ gene was used as a model system to identify specific sequence elements affecting mRNA stability. Various insertions and substitutions at the ribosome-binding site increased or decreased the rate of mRNA inactivation by up to fourfold. Deletion of a dyad symmetry, which may give rise to a very stable secondary structure in the mRNA immediately downstream of the gene, decreased the functional stability of the lacZ message. The magnitude of the latter effect was strongly dependent on the sequences at the ribosome-binding site, ranging from practically no effect for the most labile transcripts to a threefold decrease in stability for the most stable one. The results suggest that the wild-type lacZ message is inactivated predominantly by attacks near the ribosome-binding site, presumably in part because the putative secondary structure downstream of the gene protects against 3'-exonucleolytic attack. Taken together, the data for all of the modified variants of lacZ were shown to be quantitatively compatible with a general model of mRNA inactivation involving multiple independent target sites.
大肠杆菌lacZ基因被用作一个模型系统，以识别影响mRNA稳定性的特定序列元件。核糖体结合位点处的各种插入和替换使mRNA失活速率提高或降低了四倍之多。一个可能在基因下游紧邻的mRNA中产生非常稳定二级结构的二重对称序列的缺失，降低了lacZ信息的功能稳定性。后一种效应的程度强烈依赖于核糖体结合位点处的序列，从对最不稳定转录本几乎没有影响到对最稳定转录本稳定性降低三倍不等。结果表明，野生型lacZ信息主要通过核糖体结合位点附近的攻击而失活，推测部分原因是基因下游假定的二级结构可防止3' -核酸外切酶攻击。总体而言，lacZ所有修饰变体的数据在数量上与涉及多个独立靶位点的mRNA失活通用模型相符。
