Nickel coordination is regulated by the DNA-bound state of NikR.
Nat Struct Biol
; 10(2): 126-30, 2003 Feb.
Article
en En
| MEDLINE
| ID: mdl-12524532
ABSTRACT
The uptake of nickel in Escherichia coli and other microorganisms is transcriptionally regulated by the NikR repressor or its homologs. Here we report the structure of the high-affinity nickel-binding site in NikR and show that it responds dramatically to DNA binding. X-ray absorption spectroscopy reveals that nickel in the holo-NikR protein is bound in a novel four-coordinate planar site consisting of two histidines, one additional O- or N-donor ligand and one S-donor ligand. Site-directed mutation of His87, His89, Cys95 or Glu97 in NikR to alanine eliminates high-affinity nickel binding and abolishes DNA binding but maintains stable protein folding. An unanticipated feature of the NikR structure is that the nickel coordination responds to DNA binding. A six-coordinate nickel site composed of O- or N-donor ligands, but lacking cysteine, forms when NikR binds to operator DNA. Because nickel binding and DNA binding are mediated by different domains within NikR, a communication link between the two domains is implicated, consistent with the finding that the nickel-binding site in a fragment corresponding to the C-terminal domain of NikR is structurally distinct from that found in holo-NikR.
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Colección:
01-internacional
Asunto principal:
Proteínas Represoras
/
ADN
/
Níquel
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Nat Struct Biol
Asunto de la revista:
BIOLOGIA MOLECULAR
Año:
2003
Tipo del documento:
Article
País de afiliación:
Estados Unidos