title: Multiple promoters for transcription of the Escherichia coli DNA topoisomerase I gene and their regulation by DNA supercoiling.
abstract: There are four transcriptional promoters present in the 5' control region of the Escherichia coli DNA topoisomerase I (topA) gene. These were identified with Bal31 nuclease-generated deletions and mapping of the 5' ends of the mRNAs with avian reverse transcriptase. Recombinant plasmids with all or some of these promoters fused to the galactokinase (galK) gene-coding region have been constructed and used to study transcription from the promoters both in vitro and in vivo. The promoter (P1) closest to the starting ATG codon has a near consensus -35 sequence (GTTGATA) but unusual -10 (CATATCG) sequence. The other three promoters (P2, P3 and P4) are clustered together 60 base-pairs further upstream. Negative DNA supercoiling is required for efficient transcription from P1, P1 + P2 + P3 + P4, P2 + P3 + P4, P3 + P4 and P4 alone. The combination of all four promoters demonstrates greater supercoiling dependence than does any of the other subsets tested.
authors.affiliation: E. I. du Pont de Nemours and Co. Central Research and Development Department, Wilmington, DE 19898.
authors.forename: Y C
authors.initials: YC
authors.lastname: Tse-Dinh
authors.forename: R K
authors.initials: RK
authors.lastname: Beran
mesh_terms: D001483:Base Sequence; D004264:DNA Topoisomerases, Type I / Q000235:genetics*; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D004926:Escherichia coli / Q000235:genetics; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
chemical_list: D004269:DNA, Bacterial; D004278:DNA, Superhelical; D004264:DNA Topoisomerases, Type I