Rieske non-heme iron oxygenase (RO) family, Phthalate 4,5-dioxygenase (PhDO)-like subfamily, N-terminal Rieske domain of the oxygenase alpha subunit; composed of the oxygenase alpha subunits of PhDO and similar proteins including 3-chlorobenzoate 3,4-dioxygenase (CBDO), phenoxybenzoate dioxygenase (POB-dioxygenase) and 3-nitrobenzoate oxygenase (MnbA). ROs comprise a large class of aromatic ring-hydroxylating dioxygenases that enable microorganisms to tolerate and utilize aromatic compounds for growth. The oxygenase alpha subunit contains an N-terminal Rieske domain with an [2Fe-2S] cluster and a C-terminal catalytic domain with a mononuclear Fe(II) binding site. The Rieske [2Fe-2S] cluster accepts electrons from a reductase or ferredoxin component and transfers them to the mononuclear iron for catalysis. PhDO and CBDO are two-component RO systems, containing oxygenase and reductase components. PhDO catalyzes the dihydroxylation of phthalate to form the 4,5-dihydro-cis-dihydrodiol of phthalate (DHD). CBDO, together with CbaC dehydrogenase, converts the environmental pollutant 3CBA to protocatechuate (PCA) and 5-Cl-PCA, which are then metabolized by the chromosomal PCA meta (extradiol) ring fission pathway. POB-dioxygenase catalyzes the initial catabolic step in the angular dioxygenation of phenoxybenzoate, converting mono- and dichlorinated phenoxybenzoates to protocatechuate and chlorophenols. These phenoxybenzoates are metabolic products formed during the degradation of pyrethroid insecticides.
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