Probably acts as a heme chaperone, transferring heme to an unknown acceptor. Binds one molecule of heme per monomer, possibly covalently (By similarity). Binds 1 [4Fe-4S] cluster. The cluster is coordinated with 3 cysteines and an exchangeable S-adenosyl-L-methionine (By similarity). Part of the lepA-hemN operon; there is a strong transcriptional terminator between the 2 genes, this gene is much less transcribed. There can be further readthough downstream (PubMed:8757728, PubMed:9371469). Induced under anaerobic conditions by resDE, fnr and arfM. Cells lacking this gene accumulate coproporphyrinogen-III under anaerobic conditions, but show normal growth under aerobic and anaerobic conditions. Might carry two S-adenosyl-L-methionine binding sites with only one binding to the iron-sulfur cluster. Belongs to the anaerobic coproporphyrinogen-III oxidase family. HemW subfamily. Although the bacteria accumulates coproporphyrinogen-III when the gene is disrupted, no oxygen-independent coproporphyrinogen-III oxidase activity or complementation have been shown. The exact role of this protein is unknown.