Premium
Repression of deo P2 in Escherichia coli by CytR: conversion of a transcription activator into a repressor
Author(s) -
Shin Minsang,
Kang Soim,
Hyun SeokJin,
Fujita Nobuyuki,
Ishihama Akira,
ValentinHansen Poul,
Choy Hyon E.
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.19.5392
Subject(s) - biology , repressor , psychological repression , escherichia coli , activator (genetics) , transcription (linguistics) , escherichia coli proteins , genetics , enzyme repression , transcription factor , microbiology and biotechnology , gene , gene expression , linguistics , philosophy
In the deo P2 promoter of Escherichia coli , a transcription activator, cAMP–CRP, binds at two sites, centered at −41.5 and −93.5 from the start site of transcription, while a repressor, CytR, binds to a space between the two cAMP–CRP complexes. The mechanisms for the cAMP–CRP‐mediated transcription activation and CytR‐mediated transcription repression were investigated in vitro using purified components. We classified the deo P2 promoter as a class II cAMP–CRP‐dependent promoter, primarily by the action of cAMP–CRP at the downstream site. Interestingly, we also found that deo P2 carries an ‘UP‐element’ immediately upstream of the downstream cAMP–CRP site. The UP‐element overlaps with the DNA site for CytR. However, it was observed that CytR functions with the RNA polymerase devoid of the C‐terminal domain of the α‐subunit as well as with intact RNA polymerase. The mechanism of repression by CytR proposed in this study is that the cAMP–CRP bound at −41.5 undergoes an allosteric change upon direct interaction with CytR such that it no longer maintains a productive interaction with the N‐terminal domain of α, but instead acts as a repressor to interfere with RNA polymerase acting on deo P2.