DNA recognition by a σ(54) transcriptional activator from Aquifex aeolicus.
J Mol Biol
; 426(21): 3553-68, 2014 Oct 23.
Article
en En
| MEDLINE
| ID: mdl-25158097
ABSTRACT
Transcription initiation by bacterial σ(54)-polymerase requires the action of a transcriptional activator protein. Activators bind sequence-specifically upstream of the transcription initiation site via a DNA-binding domain (DBD). The structurally characterized DBDs from activators all belong to the Fis (factor for inversion stimulation) family of helix-turn-helix DNA-binding proteins. We report here structures of the free and DNA-bound forms of the DBD of NtrC4 (4DBD) from Aquifex aeolicus, a member of the NtrC family of σ(54) activators. Two NtrC4-binding sites were identified upstream (-145 and -85bp) from the start of the lpxC gene, which is responsible for the first committed step in lipid A biosynthesis. This is the first experimental evidence for σ(54) regulation in lpxC expression. 4DBD was crystallized both without DNA and in complex with the -145-binding site. The structures, together with biochemical data, indicate that NtrC4 binds to DNA in a manner that is similar to that of its close homolog, Fis. The greater sequence specificity for the binding of 4DBD relative to Fis seems to arise from a larger number of base-specific contacts contributing to affinity than for Fis.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Bacterias
/
Factores de Transcripción
/
ADN
/
Proteínas de Escherichia coli
/
Factor Proteico para Inverción de Estimulación
/
ARN Polimerasa Sigma 54
/
Proteínas PII Reguladoras del Nitrógeno
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
J Mol Biol
Año:
2014
Tipo del documento:
Article
País de afiliación:
Estados Unidos