Abstract
In Escherichia coli, the transcriptional activity of many promoters is strongly dependent on the negative superhelical density of chromosomal DNA. This, in turn, varies with the growth phase, and is correlated with the overall activity of DNA gyrase, the major topoisomerase involved in the elevation of negative superhelicity. The DNA architectural protein FIS is a regulator of the metabolic reorganization of the cell during early exponential growth phase. We have previously shown that FIS modulates the superhelical density of plasmid DNA in vivo, and on binding reshapes the supercoiled DNA in vitro. Here, we show that, in addition, FIS represses the gyrA and gyrB promoters and reduces DNA gyrase activity. Our results indicate that FIS determines DNA topology both by regulation of topoisomerase activity and, as previously inferred, by directly reshaping DNA. We propose that FIS is involved in coupling cellular physiology to the topology of the bacterial chromosome.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Base Sequence
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Blotting, Northern
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Blotting, Western
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Carrier Proteins / genetics
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Carrier Proteins / metabolism*
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DNA Footprinting
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DNA Gyrase
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DNA Topoisomerases, Type II / genetics
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DNA Topoisomerases, Type II / metabolism
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DNA, Bacterial / chemistry*
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DNA, Bacterial / genetics
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DNA, Bacterial / metabolism
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DNA, Superhelical / chemistry*
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DNA, Superhelical / genetics
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DNA, Superhelical / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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DNA-Directed RNA Polymerases / metabolism
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Escherichia coli / physiology*
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Escherichia coli Proteins*
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Factor For Inversion Stimulation Protein
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Gene Expression Regulation, Bacterial*
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Integration Host Factors
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Molecular Sequence Data
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Promoter Regions, Genetic
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Transcription, Genetic
Substances
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Carrier Proteins
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DNA, Bacterial
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DNA, Superhelical
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DNA-Binding Proteins
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Escherichia coli Proteins
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Factor For Inversion Stimulation Protein
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Integration Host Factors
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integration host factor, E coli
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DNA-Directed RNA Polymerases
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DNA Gyrase
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DNA Topoisomerases, Type II