Cell surface ferroxidase; part of the reductive iron assimilatory system (RIA), a siderophore-independent high affinity iron uptake mechanism (PubMed:23658520). Required to oxidize Fe(2+) and release it from the transporter (By similarity). Expression is repressed by iron starvation and up-regulated in the absence of the sidN siderophore synthetase (PubMed:23658520). Belongs to the multicopper oxidase family.