Unwinding of duplex DNA during transcription initiation at theEscherichia coligalactose operon overlapping promoters
- 2 July 1990
- journal article
- Published by Wiley in FEBS Letters
- Vol. 267 (1), 46-50
- https://doi.org/10.1016/0014-5793(90)80284-p
Abstract
We have used potassium permanganate as a probe to detect DNA duplex unwinding in vitro, in open complexes between E. coli RNA polymerase and DNA fragments carrying the E. coli galactose operon regulatory region. This zone contains 3 overlapping promoters which specify transcription initiation at 3 distinct startpoints. We have used mutant gal derivatives carrying different single point mutations, each of which allows initiation from only one of the 3 start sites. This has allowed us to compare duplex unwinding in open complexes at the 3 different promoters, and to show that the extent of the unwinding is similar in each case. Further, the pattern of DNA modification by potassium permanganate suggests a model for discrimination between the upper and lower strands. Finally, we show that DNA modification by potassium permanganate at the gal promoters is the same in vivo as in vitroKeywords
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