Regulatory control of the Escherichia coli O157:H7 lpf1 operon by H-NS and Ler.
J Bacteriol
; 193(7): 1622-32, 2011 Apr.
Article
em En
| MEDLINE
| ID: mdl-21278287
ABSTRACT
Long polar fimbriae 1 (Lpf1) of Escherichia coli O157H7 is a tightly regulated adhesin, with H-NS silencing the transcriptional expression of the lpf1 operon while Ler (locus of enterocyte effacement-encoded regulator) acts as an antisilencer. We mapped the minimal regulatory region of lpf1 required for H-NS- and Ler-mediated regulation and found that it is 79% AT rich. Three putative sites for H-NS binding were identified. Two of them, named silencer regulatory sequence 1 (SRS1) and SRS2, are located on a region that covers both of the lpf1 promoters (P1 and P2). The third putative H-NS binding site is located within the lpfA1 gene in a region extending from +258 bp to +545 bp downstream of ATG; however, this site does not seem to play a role in lpfA1 regulation under the conditions tested in this work. Ler was also found to interact with Ler binding sites (LBSs). Ler binding site 1 (LBS1) and LBS2 are located upstream of the two promoters. LBS1 overlaps SRS1, while LBS3 overlaps the P1 promoter and SRS2. Based on the experimental data, we propose that H-NS silences lpf1 expression by binding to both of the SRSs on the promoter region, forming an SRS-H-NS complex that prevents RNA polymerase-mediated transcription. A model of the regulation of the lpfA1 operon of E. coli O157H7 by H-NS and Ler is discussed.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Regulação Bacteriana da Expressão Gênica
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Transativadores
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Adesinas de Escherichia coli
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Escherichia coli O157
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Proteínas de Escherichia coli
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Proteínas de Fímbrias
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article