Crystallographic characterization of phthalate oxygenase reductase, an iron-sulfur flavoprotein from Pseudomonas cepacia.

Pseudomonads grown on phthalate synthesize a series of enzymes that metabolize this aromatic substrate. Among the inducible enzymes is a reductase which transfers electrons from NADH to the terminal dioxygenase that converts phthalate to the corresponding cis-1,2-dihydrodiol (Keyser, P. (1976) Ph. D. thesis, University of Miami; Ribbons, D. W., and Evans, W. C. (1960) Biochem. J. 76, 310-318). The phthalate oxygenase reductase induced in Pseudomonas cepacia is a single polypeptide chain (Mr approximately equal to 33,000) with two prosthetic groups, FMN and [2Fe-2S]. This oxidoreductase has been crystallized at pH 6.7 from polyethylene glycol 6000 in space group R3 with a = b = 113.4 A and c = 77.7 A (hexagonal indexing).