Genomic sequencing of the methanotrophic bacterium,Methylococcus cap-sulatus (Bath), revealed an open reading frame (MCA2590) immediately upstream of the previously described mopEgene (MCA2589). Sequence analyses of the deduced amino acid sequence demonstrated that the MCA2590-encoded protein shared significant, but restricted, sequence simi-larity to the bacterial di-heme cytochrome c peroxidase (BCCP) family of proteins.