Ring hydroxylating dioxygenase beta subunit. This subunit has a similar structure to NTF-2, Ketosteroid isomerase and scytalone dehydratase.The degradation of aromatic compounds by aerobic bacteria frequently begins with the dihydroxylation of the substrate by nonheme iron-containing dioxygenases. These enzymes consist of two or three soluble proteins that interact to form an electron-transport chain that transfers electrons from reduced nucleotides (NADH) via flavin and [2Fe-2S] redox centers to a terminal dioxygenase. Aromatic-ring-hydroxylating dioxygenases oxidize aromatic hydrocarbons and related compounds to cis-arene diols. These enzymes utilize a mononuclear non-heme iron center to catalyze the addition of dioxygen to their respective substrates. The active site of these enzymes however is in the alpha sub-unit. No functional role has been attributed to the beta sub-unit except for a structural role.