Rieske non-heme iron oxygenase (RO) family, Rieske ferredoxin component; composed of the Rieske ferredoxin component of some three-component RO systems including biphenyl dioxygenase (BPDO) and carbazole 1,9a-dioxygenase (CARDO). The RO family comprise a large class of aromatic ring-hydroxylating dioxygenases found predominantly in microorganisms. These enzymes enable microorganisms to tolerate and even exclusively utilize aromatic compounds for growth. ROs consist of two or three components: reductase, oxygenase, and ferredoxin (in some cases) components. The ferredoxin component contains either a plant-type or Rieske-type [2Fe-2S] cluster. The Rieske ferredoxin component in this family carries an electron from the RO reductase component to the terminal RO oxygenase component. BPDO degrades biphenyls and polychlorinated biphenyls. BPDO ferredoxin (BphF) has structural features consistent with a minimal and perhaps archetypical Rieske protein in that the insertions that give other Rieske proteins unique structural features are missing. CARDO catalyzes dihydroxylation at the C1 and C9a positions of carbazole. Rieske ferredoxins are found as subunits of membrane oxidase complexes, cis-dihydrodiol-forming aromatic dioxygenases, bacterial assimilatory nitrite reductases, and arsenite oxidase. Rieske ferredoxins are also found as soluble electron carriers in bacterial dioxygenase and monooxygenase complexes.
Jiyao W et al.(2023). "The conserved domain database in 2023.",