Nivinskas R, Vaiskunaite R, Raudonikiene A
Laboratory of Gene Engineering, Institute of Biochemistry, Vilnius, Lithuania.
J Mol Biol. 1993 Apr 5;230(3):717-21. doi: 10.1006/jmbi.1993.1192.
Analysis of the nucleotide sequence in the 5' flanking region of bacteriophage T4 gene 25 revealed three potential Shine and Dalgarno sequences, SD1, SD2 and SD3, with a spacing of 8, 17 and 27 nucleotides from the initiation codon of this gene, respectively. Results of our experiments in the bacteriophage T7 expression system clearly demonstrate that the SD3 sequence is required for efficient expression of gene 25. We propose the existence of a stem-loop structure that includes SD1 and SD2 sequences and brings the SD3 sequence to a favourable spacing with the initiation codon of gene 25. Since the predicted secondary structure in the translational initiation region of gene 25 is relatively unstable and the SD3 sequence, GAGG, is more typical than the SD1 sequence, GAG, we suggest that this structure could control the level of gene expression.
对噬菌体T4基因25的5'侧翼区域核苷酸序列的分析揭示了三个潜在的Shine和Dalgarno序列，即SD1、SD2和SD3，它们与该基因起始密码子的间距分别为8、17和27个核苷酸。我们在噬菌体T7表达系统中的实验结果清楚地表明，SD3序列是基因25高效表达所必需的。我们提出存在一种茎环结构，它包含SD1和SD2序列，并使SD3序列与基因25的起始密码子形成有利的间距。由于基因25翻译起始区域预测的二级结构相对不稳定，且SD3序列GAGG比SD1序列GAG更典型，我们认为这种结构可以控制基因表达水平。
