DNA sequence elements located immediately upstream of the -10 hexamer in Escherichia coli promoters: a systematic study.
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.
Burr
T
T
School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Mitchell
J
J
Kolb
A
A
Minchin
S
S
Busby
S
S
D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D003627:Data Interpretation, Statistical; D004926:Escherichia coli / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D004269:DNA, Bacterial; D011993:Recombinant Fusion Proteins; D012321:DNA-Directed RNA Polymerases; D001616:beta-Galactosidase