C-terminal catalytic domain of the oxygenase alpha subunit of Pseudomonas resinovorans strain CA10 anthranilate 1,2-dioxygenase and related aromatic ring hydroxylating dioxygenases
C-terminal catalytic domain of the oxygenase alpha subunit of anthranilate 1,2-dioxygenase (AntDO) and related Rieske-type non-heme iron aromatic ring-hydroxylating oxygenases (RHOs, also known as aromatic ring hydroxylating dioxygenases). RHOs utilize non-heme Fe(II) to catalyze the addition of hydroxyl groups to the aromatic ring, an initial step in the oxidative degradation of aromatic compounds. RHOs are composed of either two or three protein components, and are comprised of an electron transport chain (ETC) and an oxygenase. The ETC transfers reducing equivalents from the electron donor to the oxygenase component, which in turn transfers electrons to the oxygen molecules. The oxygenase components are oligomers, either (alpha)n or (alpha)n(beta)n. The alpha subunits are the catalytic components and have an N-terminal domain, which binds a Rieske-like 2Fe-2S cluster, and the C-terminal catalytic domain which binds the non-heme Fe(II). The Fe(II) is co-ordinated by conserved His and Asp residues. Oxygenases belonging to this subgroup include the alpha subunits of AntDO, aniline dioxygenase, Acinetobacter calcoaceticus benzoate 1,2-dioxygenase, 2-halobenzoate 1,2-dioxygenase from Pseudomonas cepacia 2CBS, 2,4,5-trichlorophenoxyacetic acid oxygenase from Pseudomonas cepacia AC1100, 2,4-dichlorophenoxyacetic acid oxygenase from Bradyrhizobium sp. strain HW13, p-cumate 2,3-dioxygenase, 2-halobenzoate 1,2-dioxygenase form Pseudomonas cepacia 2CBS, and Pseudomonas putida IacC, which may be involved in the catabolism of the plant hormone indole 3-acetic acid. This subfamily belongs to the SRPBCC (START/RHO_alpha_C/PITP/Bet_v1/CoxG/CalC) domain superfamily of proteins that bind hydrophobic ligands. SRPBCC domains have a deep hydrophobic ligand-binding pocket.