Copper transfer from the Cu(I) chaperone, CopZ, to the repressor, Zn(II)CopY: Metal coordination environments and protein interactions

Cobine, P. A., George, G. N., Jones, C. E., Wickramasinghe, W. A., Solioz, M. and Dameron, C. T. (2002) Copper transfer from the Cu(I) chaperone, CopZ, to the repressor, Zn(II)CopY: Metal coordination environments and protein interactions. Biochemistry, 41 18: 5822-5829. doi:10.1021/bi025515c


Author Cobine, P. A.
George, G. N.
Jones, C. E.
Wickramasinghe, W. A.
Solioz, M.
Dameron, C. T.
Title Copper transfer from the Cu(I) chaperone, CopZ, to the repressor, Zn(II)CopY: Metal coordination environments and protein interactions
Journal name Biochemistry   Check publisher's open access policy
ISSN 0006-2960
1943-295X
1520-4995
Publication date 2002-05-07
Sub-type Article (original research)
DOI 10.1021/bi025515c
Volume 41
Issue 18
Start page 5822
End page 5829
Total pages 8
Place of publication Washington, DC, U.S.A.
Publisher American Chemical Society
Collection year 2002
Language eng
Subject C1
321299 Public Health and Health Services not elsewhere classified
730299 Public health not elsewhere classified
Abstract Extracellular copper regulates the DNA binding activity of the CopY repressor of Enterococcus hirae and thereby controls expression of the copper homeostatic genes encoded by the cop operon. CopY has a CxCxxxxCxC metal binding motif. CopZ, a copper chaperone belonging to a family of metallochaperones characterized by a MxCxxC metal binding motif, transfers copper to CopY. The copper binding stoichiometries of CopZ and CopY were determined by in vitro metal reconstitutions. The stoichiometries were found to be one copper(l) per CopZ and two copper(l) per CopY monomer. X-ray absorption studies suggested a mixture of two- and three-coordinate copper in Cu(1)CopZ, but a purely three-coordinate copper coordination with a Cu-Cu interaction for Cu(1)(2)CopY. The latter coordination is consistent with the formation of a compact binuclear Cu(l)-thiolate core in the CxCxxxxCxC binding motif of CopY. Displacement of zinc, by copper. from CopY was monitored with 2,4-pyridylazoresorcinol. Two copper(l) ions were required to release the single zinc(II) ion bound per CopY monomer. The specificity of copper transfer between CopZ and CopY was dependent on electrostatic interactions. Relative copper binding affinities of the proteins were investigated using the chelator, diethyldithiocarbamic acid (DDC). These data suggest that CopY has a higher affinity for copper than CopZ. However, this affinity difference is not the sole factor in the copper exchange: a charge-based interaction between the two proteins is required for the transfer reaction to proceed. Gain-of-function mutation of a CopZ homologue demonstrated the necessity of four lysine residues on the chaperone for the interaction with CopY. Taken together, these results suggest a mechanism for copper exchange between CopZ and CopY.
Keyword Biochemistry & Molecular Biology
Absorption Fine-structure
Enterococcus-hirae
Atx1 Metallochaperone
Molecular Mechanisms
Transcription Factor
Crystal-structure
Disease Protein
Binding Domain
Atpase
Homeostasis
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemistry and Molecular Biosciences
 
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Created: Tue, 14 Aug 2007, 17:55:00 EST