Direct binding of the quorum sensing regulator CepR of Burkholderia cenocepacia to two target promoters in vitro.
Mol Microbiol
; 57(2): 452-67, 2005 Jul.
Article
em En
| MEDLINE
| ID: mdl-15978077
ABSTRACT
Burkholderia cenocepacia is an opportunistic human pathogen that can aggressively colonize the cystic fibrosis lung. This organism has a LuxR/LuxI-type quorum sensing system that enables cell-cell communication via exchange of acyl homoserine lactones (AHLs). The CepR and CepI proteins constitute a global regulatory system, controlling expression of at least 40 genes, including those controlling swarming motility and biofilm formation. In this study, we isolated seven lacZ fusions in a clinical isolate of B. cenocepacia that are inducible by octanoyl-HSL. Induction of all of these genes requires CepR. The cepI promoter was tested for induction by a set of 33 synthetic autoinducers and analogues, and was most strongly induced by long-chain AHLs lacking 3-oxo substitutions. Expression of this promoter was inhibited by high concentrations of three different autoinducers, each having six-carbon acyl chains. When CepR protein was overproduced in Escherichia coli, it accumulated in a soluble form in the presence of octanoyl-HSL, but accumulated only as insoluble inclusion bodies in its absence. Purified CepR-OHL complexes bound to specific DNA sequences at the cepI and aidA promoters with high specificity. These binding sites included a 16-nucleotide imperfect dyad symmetry. Both CepR binding sites are centred approximately 44 nucleotides upstream of the respective transcription start sites.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Regulação Bacteriana da Expressão Gênica
/
Regiões Promotoras Genéticas
/
Burkholderia
Idioma:
En
Ano de publicação:
2005
Tipo de documento:
Article