A
microarray-based antibiotic screen identifies a regulatory role for
supercoiling in the osmotic stress response of Escherichia coli
Kevin
J. Cheung, Vasudeo Badarinarayana, Douglas Selinger, Daniel Janse, and George
M. Church
Changes in DNA supercoiling are
induced by a wide range of environmental stresses in Escherichia coli,
but the physiological significance of these responses remains unclear. We now demonstrate that an increase in
negative supercoiling is necessary for transcriptional activation of a large
subset of osmotic stress response genes.
Using a microarray-based
approach, we have characterized supercoiling-dependent gene transcription by
expression profiling under conditions of high salt, in conjunction with
microbial antibiotics novobiocin, pefloxacin, and chloramphenicol. Algorithmic clustering and statistical
measures for gauging cellular function show that this subset is enriched for
genes critical in osmoprotectant transport/synthesis and rpoS-driven stationary phase adaptation.
Transcription factor binding site analysis also supports regulation by
the global stress sigma factor rpoS. In
addition, these studies implicate 60 uncharacterized genes in the osmotic
stress regulon, and offer evidence for a broader role for supercoiling in the
control of stress-induced transcription.
Contents
Copyright (c) 2002 by Kevin
Cheung and the President and Fellows of