Journal of Bacteriology, August 2000, p. 4180-4187, Vol. 182, No. 15
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
andDepartment of Biological Chemistry, UCLA School of Medicine, Los Angeles, California 90095-1737,1 and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, California 900952
Received 27 January 2000/Accepted 26 April 2000
The Escherichia coli proP P2 promoter, which directs
the expression of an integral membrane transporter of proline, glycine betaine, and other osmoprotecting compounds, is induced upon entry into
stationary phase to protect cells from osmotic shock. Transcription from the P2 promoter is completely dependent on RpoS
(
38) and Fis. Fis activates transcription by binding to
a site centered at
41, which overlaps the promoter, where it makes a
specific contact with the C-terminal domain of the
subunit of RNA
polymerase (
-CTD). We show here that Fis and cyclic AMP (cAMP)
receptor protein (CRP)-cAMP collaborate to activate transcription
synergistically in vitro. Coactivation both in vivo and in vitro is
dependent on CRP binding to a site centered at
121.5, but CRP without
Fis provides little activation. The contribution by CRP requires the correct helical phasing of the CRP site and a functional activation region 1 on CRP. We provide evidence that coactivation is achieved by
Fis and CRP independently contacting each of the two
-CTDs. Efficient transcription in vitro requires that both activators must be
preincubated with the DNA prior to addition of RNA polymerase.
Present address: West Los Angeles VA Medical Center, Los Angeles,
CA 90073.
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