Required for copper resistance. In vitro, oxidizes organic substrates and Fe(2+). May act in vivo by oxidation of toxic periplasmic Cu(+). 4 Fe(2+) + 4 H(+) + O2 = 4 Fe(3+) + 2 H2O Binds 4 Cu cations per monomer. Could be associated with the membrane through a lipidation site. Repressed by RicR (PubMed:24549843). Induced by copper (PubMed:23772064, PubMed:24549843). Predicted to be exported by the Tat system. The position of the signal peptide cleavage has not been experimentally proven. Mutant is more sensitive to copper (PubMed:23772064, PubMed:24549843). Deletion does not affect virulence in mice (PubMed:24549843). Overexpression results in copper hyperresistance but not hypervirulence. Belongs to the multicopper oxidase family.