The crystal structure of the CopC protein from Pseudomonas fluorescens reveals amended classifications for the CopC protein family.
Udagedara, S.R., Wijekoon, C.J.K., Xiao, Z., Wedd, A.G., Maher, M.J.(2019) J Inorg Biochem 195: 194-200
- PubMed: 30981030 
- DOI: https://doi.org/10.1016/j.jinorgbio.2019.03.007
- Primary Citation of Related Structures:  
6NFQ, 6NFR, 6NFS - PubMed Abstract: 
The bacterial CopC family of proteins are periplasmic copper binding proteins that act in copper detoxification. These proteins contain Cu(I) and/or Cu(II) binding sites, with the family that binds Cu(II) only the most prevalent, based on sequence analyses. Here we present three crystal structures of the CopC protein from Pseudomonas fluorescens (Pf-CopC) that include the wild type protein bound to Cu(II) and two variant proteins, where Cu(II) coordinating ligands were mutated, in Cu-free states. We show that the Cu(II) atom in Pf-CopC is coordinated by two His residues, an Asp residue and the N-terminus of the protein (therefore a 3N + O site). This coordination structure is consistent with all structurally characterized proteins from the CopC family to date. Structural and sequence analyses of the CopC family allow a relationship between protein sequence and the Cu(II) binding affinity of these proteins to be proposed.
Organizational Affiliation: 
Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3083, Australia.