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J. Bacteriol., 09 1997, 5736-5743, Vol 179, No. 18
D Murphree, B Froehlich and JR Scott
The adherence of enterotoxigenic Escherichia coli (ETEC) to the human small
intestine is an important early event in infection. Attachment is thought
to be mediated by proteinaceous structures called pili. We have
investigated the regulation of expression of the genes encoding CS1 pili
found on human ETEC strains and find that there are at least three
promoters, P1 and P2, upstream of the coo genes, and P3, downstream of the
start of cooB translation. We identified a silencer of transcription which
extends over several hundred bases overlapping the cooB open reading frame.
This silencer is dependent on the promoter and/or upstream region for its
negative effect. The DNA binding protein H-NS is a repressor of coo
transcription that acts in the same region as the silencer, so it is
possible that H-NS is involved in this silencing. Rns, a member of the AraC
family, positively regulates transcription of the coo operon and relieves
the silencing of CS1 expression.
Copyright © 1997, American Society for Microbiology
Transcriptional control of genes encoding CS1 pili: negative regulation by a silencer and positive regulation by Rns
Department of Microbiology and Immunology, Emory University, Atlanta, Georgia 30322, USA.
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