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 [2Fe-2S] cluster. Although this protein has sequence motifs typically found in proteins binding the [4Fe-4S]-AdoMet radical-SAM cluster and S-adenosylmethionine, spectroscopic evidence suggests that a [2Fe-2S] cluster is present; S-adenosylmethionine was not detected. Has no detectable coproporphyrinogen-III oxidase activity (PubMed:20194361). Induced under microoxic conditions. Cells lacking this gene have no detectable phenotype. 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.