CopY is a copper-inducible repressor of the Enterococcus hirae copper ATPases.
J Biol Chem
; 272(14): 8932-6, 1997 Apr 04.
Article
em En
| MEDLINE
| ID: mdl-9083014
ABSTRACT
The cop operon of Enterococcus hirae effects copper homeostasis in this organism. It encodes a repressor, CopY, an activator, CopZ, and two P-type copper ATPases, CopA and CopB. Expression of all four genes is regulated by the ambient copper. In this regulation, CopY apparently acts as a copper-inducible repressor. By DNase I footprinting, it was shown that purified CopY protected two discrete sites in the region encompassing nucleotides -71 to -11 relative to the translational start site and containing hyphenated inverted repeats. Transcription is initiated between these repeats at nucleotide -42, in a domain that remained accessible to DNase I in the DNA-repressor complex. Chemical cross-linking revealed that CopY exists as a dimer in solution. In DNA band-shift assays, it was apparent that the CopY-DNA interaction occurred in two discrete steps. Half-maximal binding of repressor to the two operator sites was observed at 2 x 10(-9) M and 5 x 10(-9) M CopY, respectively. Copper ions released CopY from the promoter/operator with an apparent half-binding constant for Cu(I) of 20 microM. The site-directed mutations A-61T and A-30T essentially abolished the binding of CopY to the respective binding sites, and the double mutation A-61T/A-30T inactivated both binding sites. Thus, CopY is a copper-inducible repressor of the cop operon of E. hirae, exhibiting highly specific DNA-protein interactions with two sites on the cop promoter/operator and playing a key role in copper homeostasis in E. hirae.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Repressoras
/
Proteínas de Bactérias
/
Proteínas de Transporte
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Adenosina Trifosfatases
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Cobre
/
Proteínas de Transporte de Cátions
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
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