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DNA Bending and the Initiation of Transcription at σ 54-Dependent Bacterial Promoters
Manuel Carmona, Felix Claverie-Martin and Boris Magasanik
Proceedings of the National Academy of Sciences of the United States of America
Vol. 94, No. 18 (Sep. 2, 1997), pp. 9568-9572
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/43064
Page Count: 5
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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 σ 54-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 σ 54-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-σ 54 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.
Proceedings of the National Academy of Sciences of the United States of America © 1997 National Academy of Sciences