Repression of deoP2 in Escherichia coli by CytR: conversion of a transcription activator into a repressor
AUTOR(ES)
Shin, Minsang
FONTE
Oxford University Press
RESUMO
In the deoP2 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 deoP2 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 deoP2 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 deoP2.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=125655Documentos Relacionados
- Identification of the nucleotide sequence recognized by the cAMP-CRP dependent CytR repressor protein in the deoP2 promoter in E. coli.
- Identification of the Escherichia coli deoR and cytR gene products.
- The CytR repressor antagonizes cyclic AMP-cyclic AMP receptor protein activation of the deoCp2 promoter of Escherichia coli K-12.
- Single amino acid substitutions in the cAMP receptor protein specifically abolish regulation by the CytR repressor in Escherichia coli.
- Characterization of cytR mutations that influence oligomerization of mutant repressor subunits.