Proteins in this entry are encoded within a conserved gene four-gene neighbourhood found sporadically in a phylogenetically broad range of bacteria including: Nocardia farcinica, Symbiobacterium thermophilum, and Streptomyces avermitilis (Actinobacteria), Geobacillus kaustophilus (Firmicutes), Azoarcus sp. EbN1 and Ralstonia solanacearum (Beta-proteobacteria).