title: Structure and assembly of protocatechuate 3,4-dioxygenase.
abstract: Dioxygenases catalyse the cleavage of molecular oxygen with subsequent incorporation of both oxygen atoms into organic substrates. Some of the best-studied dioxygenases have been isolated from bacteria where they catalyse the critical ring-opening step in the biodegradation of aromatic compounds. These bacterial enzymes generally contain nonheme ferric iron as the sole cofactor. Protocatechuate 3,4-dioxygenase (3,4-PCD) was one of the first such enzymes recognized and catalyses the intradiol cleavage of protocatechuic acid by oxygen to produce beta-carboxy-cis,cis-muconic acid. Previous studies have shown that the 3,4-PCD found in Pseudomonas aeruginosa is an oligomer with a relative molecular mass (Mr) of 587,000 (587K) containing 12 copies each of alpha (22.3K) and beta (26.6K) subunits. The X-ray structure determination of 3,4-PCD reveals the catalytic iron environment required for oxygenolytic cleavage of aromatic rings and also provides a novel holoenzyme assembly with cubic 23(T) symmetry and first examples of mixed beta-barrel domains.
authors.affiliation: E. I. du Pont de Nemours and Co., Central Research and Development Department, Wilmington, Delaware 19880-0228.
authors.forename: D H
authors.initials: DH
authors.lastname: Ohlendorf
authors.forename: J D
authors.initials: JD
authors.lastname: Lipscomb
authors.forename: P C
authors.initials: PC
authors.lastname: Weber
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010105:Oxygenases; D011520:Protocatechuate-3,4-Dioxygenase
chemical_list: D010105:Oxygenases; D011520:Protocatechuate-3,4-Dioxygenase