DNA Bending and the Initiation of Transcription at σ 54-Dependent Bacterial Promoters
Abstract
We have examined the effects on transcription initiation of promoter and enhancer strength and of the curvature of the DNA separating these entities on wild-type and mutated enhancer-promoter regions at the Escherichia coli σ54-dependent promoters glnAp2 and glnHp2 on supercoiled and linear DNA. Our results, together with previously reported observations by other investigators, show that the initiation of transcription on linear DNA requires a single intrinsic or induced bend in the DNA, as well as a promoter with high affinity for σ54-RNA polymerase, but on supercoiled DNA requires either such a bend or a high affinity promoter but not both. The examination of the DNA sequence of all nif gene activator- or nitrogen regulator I-σ54 promoters reveals that those lacking a binding site for the integration host factor have an intrinsic single bend in the DNA separating enhancer from promoter.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- September 1997
- DOI:
- 10.1073/pnas.94.18.9568
- Bibcode:
- 1997PNAS...94.9568C