Distinct characteristics of Ag+ and Cd2+ binding to CopZ from Bacillus subtilis

Kihlken, Margaret A., Singleton, Chloe and Le Brun, Nick E. ORCID: https://orcid.org/0000-0001-9780-4061 (2008) Distinct characteristics of Ag+ and Cd2+ binding to CopZ from Bacillus subtilis. JBIC Journal of Biological Inorganic Chemistry, 13 (6). pp. 1011-1023. ISSN 0949-8257

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Abstract

The chaperone CopZ together with the P-type ATPase transporter CopA constitute a copper-detoxification system in Bacillus subtilis that is commonly found in bacteria and higher cells. Previous studies of the regulation of the copZA operon showed that expression is significantly upregulated in response to elevated concentrations of environmental silver and cadmium, as well as copper. Here, we have used spectroscopic and bioanalytical methods to investigate in detail the capacity of CopZ to bind these metal ions (as Ag(+) and Cd(2+)). We demonstrate that Ag(+) binding mimics closely that of Cu(+): Ag(+)-mediated dimerisation of the protein occurs, and distinct Ag(+)-bound species are formed at higher Ag(+) loadings. Cd(2+) also binds to CopZ, but exhibits significantly different behaviour. Cd(2+)-mediated dimerisation is only observed at low loadings, such that at 0.5 and one Cd(2+) per CopZ the protein is present mainly in a monomeric form; and multinuclear higher-order forms of Cd(2+)-CopZ are not observed. Competition binding studies reveal that Ag(+) binds with an affinity very similar to that of Cu(+), while Cd(2+) binding is significantly weaker. These data provide support for the proposal that CopZ may be involved in the detoxification of silver and cadmium, in addition to copper.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Chemistry (former - to 2024)
UEA Research Groups:	Faculty of Science > Research Groups > Chemistry of Life Processes Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry Faculty of Science > Research Groups > Biophysical Chemistry (former - to 2017) Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Depositing User:	Rachel Smith
Date Deposited:	07 Apr 2011 14:07
Last Modified:	24 Sep 2024 09:28
URI:	https://ueaeprints.uea.ac.uk/id/eprint/28491
DOI:	10.1007/s00775-008-0388-1

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