DNA footprints of the two kinetically significant intermediates in formation of an RNA polymerase-promoter open complex: evidence that interactions with start site and downstream DNA induce sequential conformational changes in polymerase and DNA.

Autor: Craig ML; Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA., Tsodikov OV, McQuade KL, Schlax PE Jr, Capp MW, Saecker RM, Record MT Jr
Jazyk: angličtina
Zdroj: Journal of molecular biology [J Mol Biol] 1998 Nov 06; Vol. 283 (4), pp. 741-56.
DOI: 10.1006/jmbi.1998.2129
Abstrakt: Kinetic studies of formation and dissociation of open-promoter complexes (RPo) involving Esigma70 RNA polymerase (R) and the lambdaPR promoter (P) demonstrate the existence of two kinetically significant intermediates, designated I1 and I2, and facilitate the choice of conditions under which each accumulates. For such conditions, we report the results of equilibrium and transient DNase I and KMnO4 footprinting studies which characterize I1 and I2. At 0 degreesC, where extrapolation of equilibrium data indicates I1 is the dominant complex, DNA bases in the vicinity of the transcription start site (+1) do not react with KMnO4, indicating that this region is closed in I1. However, the DNA backbone in I1 is extensively protected from DNase I cleavage; the DNase I footprint extends approximately 30 bases downstream and at least approximately 40 bases upstream from the start site. I1 has a short lifetime ( (Copyright 1998 Academic Press.)
Databáze: MEDLINE
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