Regulation of high affinity nickel uptake in bacteria. Ni2+-Dependent interaction of NikR with wild-type and mutant operator sites.
J Biol Chem
; 275(26): 19735-41, 2000 Jun 30.
Article
en En
| MEDLINE
| ID: mdl-10787413
ABSTRACT
Escherichia coli actively imports nickel via the ATP-dependent NikABCDE permease. NikR, a protein of the ribbon-helix-helix family of transcription factors, represses expression of the nikABCDE operon in the presence of excessive concentrations of intracellular nickel. Here, the NikR operator site is identified within the nikABCDE promoter by footprinting and mutational analyses. The operator consists of two dyad-symmetric 5'-GTATGA-3' recognition sequences separated by 16 base pairs. Mutations in the GTATGA sequences reduce NikR binding affinity in vitro and reduce repression of a P(nik)-lacZ fusion in vivo. Moreover, NikR is shown to be a direct sensor of nickel ions. Strong operator binding requires the continual presence of 20-50 micrometer nickel, indicating the presence of a low affinity nickel-binding site, and NikR dimers also contain two high affinity nickel-binding sites. In addition to both GTATGA sites and nickel, high affinity operator binding also requires the C-terminal domain of NikR.
Buscar en Google
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Represoras
/
Regiones Operadoras Genéticas
/
Proteínas de Escherichia coli
/
Escherichia coli
/
Níquel
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
J Biol Chem
Año:
2000
Tipo del documento:
Article
País de afiliación:
Estados Unidos