Open AccessA Copper Relay System Involving Two Periplasmic Chaperones Drives cbb3-Type Cytochrome c Oxidase Biogenesis in Rhodobacter capsulatus
Author(s) -
PetruIulian Trasnea,
Andreea Andrei,
Dorian Marckmann,
Marcel Utz,
Bahia Khalfaoui-Hassani,
Nur Selamoglu,
Fevzi Daldal,
HansGeorg Koch
Publication year - 2018
Publication title -
acs chemical biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.899
H-Index - 111
eISSN - 1554-8937
pISSN - 1554-8929
DOI - 10.1021/acschembio.8b00293
Subject(s) - biogenesis , periplasmic space , rhodobacter , biochemistry , cytochrome , cytochrome c oxidase , electron transport complex iv , biology , chemistry , enzyme , mutant , escherichia coli , gene
PccA and SenC are periplasmic copper chaperones required for the biogenesis of cbb 3 -type cytochrome c oxidase ( cbb 3 -Cox) in Rhodobacter capsulatus at physiological Cu concentrations. However, both proteins are dispensable for cbb 3 -Cox assembly when the external Cu concentration is high. PccA and SenC bind Cu using Met and His residues and Cys and His residues as ligands, respectively, and both proteins form a complex during cbb 3 -Cox biogenesis. SenC also interacts directly with cbb 3 -Cox, as shown by chemical cross-linking. Here we determined the periplasmic concentrations of both proteins in vivo and analyzed their Cu binding stoichiometries and their Cu(I) and Cu(II) binding affinity constants ( K D ) in vitro. Our data show that both proteins bind a single Cu atom with high affinity. In vitro Cu transfer assays demonstrate Cu transfer both from PccA to SenC and from SenC to PccA at similar levels. We conclude that PccA and SenC constitute a Cu relay system that facilitates Cu delivery to cbb 3 -Cox.