Odjakova M, Golshani A, Ivanov G, Abou Haidar M, Ivanov I
Department of Biochemistry, Faculty of Biology, University of Sofia, Bulgaria.
Microbiol Res. 1998 Aug;153(2):173-8. doi: 10.1016/S0944-5013(98)80037-2.
Recent studies have shown that the canonical Shine-Dalgarno (SD)-anti-SD interaction is dispensable for the initiation of translation of certain mRNAs in Escherichia coli. Alternative non-SD sequences (located upstream from the initiation codon) and also downstream sequences ("downstream boxes") complementary to 16S rRNA were found to be involved in the initiation of translation of mRNAs devoid of either SD or any leader sequences. In this study the chloramphenicol acetyltransferase (CAT) gene was modified to remove the 5' terminal non-translated region and/or the two potential downstream boxes in the CAT gene. Thus a series of ten CAT gene constructs was created and expressed in E. coli under a strong constitutive promoter. The results showed that CAT mRNAs devoid of both leader sequence nucleotides and the two downstream boxes in the CAT gene remained active in vivo and produced CAT protein in sufficient amounts for survival of the transformed cells at chloramphenicol concentrations up to 20-30 micrograms/ml.
最近的研究表明，典型的夏因-达尔加诺（Shine-Dalgarno，SD）-反SD相互作用对于大肠杆菌中某些mRNA的翻译起始并非必需。人们发现，替代的非SD序列（位于起始密码子上游）以及与16S rRNA互补的下游序列（“下游框”）参与了缺乏SD或任何前导序列的mRNA的翻译起始。在本研究中，氯霉素乙酰转移酶（CAT）基因经过修饰，去除了5'末端非翻译区和/或CAT基因中的两个潜在下游框。由此构建了一系列十个CAT基因构建体，并在强组成型启动子的驱动下在大肠杆菌中表达。结果表明，缺乏前导序列核苷酸以及CAT基因中两个下游框的CAT mRNA在体内仍保持活性，并产生足够量的CAT蛋白，以使转化细胞在氯霉素浓度高达20 - 30微克/毫升的情况下存活。
