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Biochem J. 1988 Mar 15;250(3):897-902.

Binding of the cyclic AMP receptor protein of Escherichia coli to RNA polymerase.

Author information

1
Department of Biology, University of York, U.K.

Abstract

Fluorescence polarization studies were used to study the interaction of a fluorescein-labelled conjugate of the Escherichia coli cyclic AMP receptor protein (F-CRP) and RNA polymerase. Under conditions of physiological ionic strength, F-CRP binds to RNA polymerase holoenzyme in a cyclic AMP-dependent manner; the dissociation constant was about 3 microM in the presence of cyclic AMP and about 100 microM in its absence. Binding to core RNA polymerase under the same conditions was weak (Kdiss. approx. 80-100 microM) and independent of cyclic AMP. Competition experiments established that native CRP and F-CRP compete for the same binding site on RNA polymerase holoenzyme and that the native protein binds about 3 times more strongly than does F-CRP. Analytical ultracentrifuge studies showed that CRP binds predominantly to the monomeric rather than the dimeric form of RNA polymerase.

PMID:
2839152
PMCID:
PMC1148940
DOI:
10.1042/bj2500897
[Indexed for MEDLINE]
Free PMC Article

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