The Cu chaperone CopZ is required for Cu homeostasis in Rhodobacter capsulatus and influences cytochrome cbb3 oxidase assembly. Issue 3 (31st January 2019)

• Record Type: Journal Article
• Authors: Utz, Marcel; Andrei, Andreea; Milanov, Martin; Trasnea, Petru‐Iulian; Marckmann, Dorian; Daldal, Fevzi; Koch, Hans‐Georg
• Is Part Of: Molecular microbiology. Volume 111:Issue 3(2019)
• Page Start: 764
• Page End: 783
• Publication Date: 2019-01-31
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.14190
• Languages: English
• ISSNs: 0950-382X

Abstract

Summary: Cu homeostasis depends on a tightly regulated network of proteins that transport or sequester Cu, preventing the accumulation of this toxic metal while sustaining Cu supply for cuproproteins. In Rhodobacter capsulatus, Cu‐detoxification and Cu delivery for cytochrome c oxidase ( cbb 3 ‐Cox) assembly depend on two distinct Cu‐exporting P1B ‐type ATPases. The low‐affinity CopA is suggested to export excess Cu and the high‐affinity CcoI feeds Cu into a periplasmic Cu relay system required for cbb 3 ‐Cox biogenesis. In most organisms, CopA‐like ATPases receive Cu for export from small Cu chaperones like CopZ. However, whether these chaperones are also involved in Cu export via CcoI‐like ATPases is unknown. Here we identified a CopZ‐like chaperone in R. capsulatus, determined its cellular concentration and its Cu binding activity. Our data demonstrate that CopZ has a strong propensity to form redox‐sensitive dimers via two conserved cysteine residues. A Δ copZ strain, like a Δ copA strain, is Cu‐sensitive and accumulates intracellular Cu. In the absence of CopZ, cbb 3 ‐Cox activity is reduced, suggesting that CopZ not only supplies Cu to P1B ‐type ATPases for detoxification but also for cuproprotein assembly via CcoI. This finding was further supported by the identification of a ~150 kDa CcoI‐CopZ protein complex in native R. capsulatus membranes. Abstract : The Rhodobacter capsulatus Cu chaperone CopZ executes a dual function. At low Cu concentrations it feeds Cu to the P1B‐type ATPase CcoI, which transfers Cu to two periplasmic Cu chaperones and ultimately to cbb3‐type cytochrome oxidase. At high Cu concentrations, however, CopZ delivers Cu to a second P1B‐type ATPase, CopA, for Cu detoxification.