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J. Bacteriol., 11 1996, 6238-6249, Vol 178, No. 21
AS Lynch and EC Lin
ArcA protein bearing an amino-terminal, oligohistidine extension has been
purified, and its DNA binding activity has been characterized with or
without prior incubation with carbamoyl phosphate. Electrophoretic mobility
shift assays and DNase I protection assays indicate that where the
phosphorylated form of the ArcA protein (ArcA-P) is expected to act as a
transcriptional repressor (e.g., of lctPRD and gltA-sdhCDAB), the effect is
likely to be mediated by sequestration of cis-controlling transcriptional
regulatory elements. In contrast, in the case of cydAB, for which ArcA-P is
expected to function as a transcriptional activator, two discrete binding
sites have been identified upstream of a known promoter, and activation
from these sites is likely to be mediated by a mechanism typical of the
type I class of prokaryotic transcriptional activators. An additional
ArcA-P binding site has also been located downstream of the known promoter,
and a distinct role for this site in the regulation of the cydAB operon
during anoxic growth transitions is suggested. These results are discussed
within the framework of an overall model of signaling by the Arc
two-component signal transduction system in response to changes in
aerobiosis.
Copyright © 1996, American Society for Microbiology
Transcriptional control mediated by the ArcA two-component response regulator protein of Escherichia coli: characterization of DNA binding at target promoters
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
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