Related Experiment Video
Updated: Jul 25, 2026

DNA-affinity-purified Chip (DAP-chip) Method to Determine Gene Targets for Bacterial Two component Regulatory Systems
Published on: July 21, 2014
DNA bending and the initiation of transcription at sigma54-dependent bacterial promoters
M Carmona1, F Claverie-Martin, B Magasanik
1Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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 sigma54-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 sigma54-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-sigma54 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.
Related Concept Videos
Bacterial RNA Polymerase
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
RNA Polymerase II Accessory Proteins
Bacterial Transcription
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
Transcription Initiation
The promoters and enhancers and their accessory proteins allow tight regulation of...
Transcription in Prokaryotes
Coordination of Gene Expression Processes in Bacteria

