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Copper trafficking in the CsoR regulon of Streptomyces lividans

Chaplin, AK and Tan, BG and Vijgenboom, E and Worrall, JAR (2015) 'Copper trafficking in the CsoR regulon of Streptomyces lividans.' Metallomics, 7 (1). 145 - 155. ISSN 1756-5901

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In the actinobacterium Streptomyces lividans copper homeostasis is controlled through the action of the metalloregulator CsoR. Under copper stress, cuprous ions bind to apo-CsoR resulting in the transcriptional derepression of genes encoding for copper efflux systems involving CopZ-like copper chaperones and CopA-like P-type ATPases. Whether CsoR obtains copper via a protein-protein mediated trafficking mechanism is unknown. In this study we have characterised the copper trafficking properties of two S. lividans CopZ proteins (SLI-1317 and SLI-3079) under the transcriptional control of a CsoR (SLI-4375). Our findings indicate that both CopZ-proteins have cysteine residues in the Cu(i) binding MX1CX2X3C motif with acid-base properties that are modulated for a high cuprous ion affinity and favourable Cu(i)-exchange with a target. Using electrophoretic mobility shift assays transfer of Cu(i) is shown to occur in a unidirectional manner from the CopZ to the CsoR. This transfer proceeds via a shallow thermodynamic affinity gradient and is also kinetically favoured through the modulation of the acid-base properties of the cysteine residues in the Cys2His cuprous ion binding motif of CsoR. Using RNA-seq coupled with the mechanistic insights of Cu(i) transfer between CopZ and CsoR in vitro, we propose a copper trafficking pathway for the CsoR regulon that initially involves the buffering of cytosolic copper by three CopZ chaperones followed by transfer of Cu(i) to CsoR to illicit a transcriptional response.

Item Type: Article
Subjects: Q Science > Q Science (General)
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 08 Jul 2015 16:04
Last Modified: 22 Jun 2021 19:15

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