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Mol Microbiol. 2016 Apr;100(2):345-61. doi: 10.1111/mmi.13321. Epub 2016 Feb 28.

Cooperation between two periplasmic copper chaperones is required for full activity of the cbb3 -type cytochrome c oxidase and copper homeostasis in Rhodobacter capsulatus.

Author information

1
Institut für Biochemie und Molekularbiologie, ZBMZ, Stefan-Meier-Strasse 17, 79104, Freiburg, Germany.
2
Fakultät für Biologie, Albert-Ludwigs-Universität Freiburg, 79104, Freiburg, Germany.
3
Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.

Abstract

Copper (Cu) is an essential micronutrient that functions as a cofactor in several important enzymes, such as respiratory heme-copper oxygen reductases. Yet, Cu is also toxic and therefore cells engage a highly coordinated Cu uptake and delivery system to prevent the accumulation of toxic Cu concentrations. In this study, we analyzed Cu delivery to the cbb3 -type cytochrome c oxidase (cbb3 -Cox) of Rhodobacter capsulatus. We identified the PCuA C-like periplasmic chaperone PccA and analyzed its contribution to cbb3 -Cox assembly. Our data demonstrate that PccA is a Cu-binding protein with a preference for Cu(I), which is required for efficient cbb3 -Cox assembly, in particular, at low Cu concentrations. By using in vivo and in vitro cross-linking, we show that PccA forms a complex with the Sco1-homologue SenC. This complex is stabilized in the absence of the cbb3 -Cox-specific assembly factors CcoGHIS. In cells lacking SenC, the cytoplasmic Cu content is significantly increased, but the simultaneous absence of PccA prevents this Cu accumulation. These data demonstrate that the interplay between PccA and SenC not only is required for Cu delivery during cbb3 -Cox assembly but also regulates Cu homeostasis in R. capsulatus.

PMID:
26718481
PMCID:
PMC4878679
DOI:
10.1111/mmi.13321
[Indexed for MEDLINE]
Free PMC Article

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