Role of the transcriptional activator RocR in the arginine-degradation pathway of Bacillus subtilis.
Mol Microbiol
; 24(4): 825-37, 1997 May.
Article
en En
| MEDLINE
| ID: mdl-9194709
ABSTRACT
In Bacillus subtilis, genes involved in arginine and ornithine catabolism constitute two operons, rocABC and rocDEF. Inducible expression of these two operons is SigL-dependent and requires the transcriptional activator RocR. RocR is a member of the NtrC/NifA family of regulators. To study the molecular mechanisms leading to the activation of RocR, we constructed a series of mutants affected in various steps of arginine catabolism. Results obtained using these mutants strongly suggest that the true inducer is ornithine or citrulline. Constitutive mutants of rocR containing either missense mutations, frameshift mutations resulting from deletions, or in-frame deletions leading to the synthesis of N-terminal truncated RocR polypeptides were obtained. Analysis of these mutants indicates that the N-terminal part of RocR is an intramolecular repressor domain. AhrC is a second positive regulatory protein of the rocABC and rocDEF operons. Two missense mutations modifying the N-terminal domain of RocR led to high constitutive expression of the Roc regulon in the absence of AhrC. Constitutive RocR proteins still require the presence of UAS1 and therefore probably bending of the DNA region located between the UAS1 and the promoter, suggesting that AhrC is not involved in DNA bending which facilitates interaction between RocR and sigma54-RNA polymerase. We suggest that the positive role of AhrC involves protein-protein interaction with RocR.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Arginina
/
Bacillus subtilis
/
Proteínas Bacterianas
/
Regulación Bacteriana de la Expresión Génica
/
Transactivadores
Idioma:
En
Revista:
Mol Microbiol
Asunto de la revista:
BIOLOGIA MOLECULAR
/
MICROBIOLOGIA
Año:
1997
Tipo del documento:
Article
País de afiliación:
Francia