DNA sequence elements located immediately upstream of the -10 hexamer in Escherichia coli promoters: a systematic study

作者：Tom Burr, J. Mitchell, Annie Kolb, Steve Minchin, Stephen J. W. Busby · 发表于：Nucleic Acids Research · 年份：2000 · DOI：10.1093/nar/28.9.1864 · 被引用次数：153 · 研究领域：Bacterial Genetics and Biotechnology、DNA and Nucleic Acid Chemistry、RNA and protein synthesis mechanisms

We have made a systematic study of how the activity of an Escherichia coli promoter is affected by the base sequence immediately upstream of the -10 hexamer. Starting with an activator-independent promoter, with a 17 bp spacing between the -10 and -35 hexamer elements, we constructed derivatives with all possible combinations of bases at positions -15 and -14. Promoter activity is greatest when the 'non-template' strand carries T and G at positions -15 and -14, respectively. Promoter activity can be further enhanced by a second T and G at positions -17 and -16, respectively, immediately upstream of the first 'TG motif'. Our results show that the base sequence of the DNA segment upstream of the -10 hexamer can make a significant contribution to promoter strength. Using published collections of characterised E.coli promoters, we have studied the frequency of occurrence of 'TG motifs' upstream of the promoters' -10 elements. We conclude that correctly placed 'TG motifs' are found at over 20% of E.coli promoters.