Li Y, Guerrier-Takada C, Altman S
Department of Biology, Yale University, New Haven, CT 06520.
Proc Natl Acad Sci U S A. 1992 Apr 15;89(8):3185-9. doi: 10.1073/pnas.89.8.3185.
External guide sequences (EGSs) complementary to mRNAs that encode beta-galactosidase from Escherichia coli and nuclease A from Staphylococcus aureus can target these RNAs for cleavage in vitro by RNase P from E. coli. Specific cleavage occurs at locations predicted by the nucleotide sequences of the EGSs. EGSs with regions complementary to the mRNAs that are as short as 13 nucleotides function efficiently and turn over slowly during incubation with the target substrate and the enzyme. EGSs composed of deoxyribonucleotides as well as those composed of ribonucleotides are effective, but cleavage of the targeted substrate with DNA as an EGS is about 10-fold less efficient than that with RNA as an EGS. An RNA EGS inhibited the formation of beta-galactosidase activity in a crude extract (S30) of E. coli that was capable of catalyzing coupled transcription-translation reactions.
与来自大肠杆菌的β-半乳糖苷酶和来自金黄色葡萄球菌的核酸酶A的mRNA互补的外部引导序列（EGS），可以在体外将这些RNA靶向，由大肠杆菌的RNase P进行切割。特异性切割发生在EGS核苷酸序列预测的位置。与mRNA互补区域短至13个核苷酸的EGS功能高效，并且在与靶底物和酶孵育期间周转缓慢。由脱氧核糖核苷酸组成的EGS以及由核糖核苷酸组成的EGS都是有效的，但是以DNA作为EGS对靶向底物的切割效率比以RNA作为EGS低约10倍。一种RNA EGS抑制了大肠杆菌粗提取物（S30）中β-半乳糖苷酶活性的形成，该提取物能够催化偶联的转录-翻译反应。
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