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Intradiol Dioxygenases

Protocatechuate 3,4-dioxygenase (PCD) catalyzes the cleavage of protocatechuate (3,4-dihydroxybenzoate) between the aromatic hydroxyls.The structure of PCD forms a 547,000 dalton (AlphaBetaFe)12 dodecamer in Pseudomonas putida and Acinetobacter calcoaceticus and a 312,000 dalton (AlphaBetaFe)6 hexamer in Brevibacterium fuscum. The structure of all three PCD's have been determined by the Ohlendorf lab. In addition, the structure of 13 complexes of PCD from P.putida with substrates and inhibitors have been used to provide structures for intermediates in the reaction pathway. The key finding has been the first visualization of ligand dissociation as a normal step in metalloenzyme catalysis. 

Work on PCD is in collaboration with Dr. John Lipscomb of the Dept. of Biochemistry and with Dr. L. Nicholas Ornston of the Department of Biology at Yale University. 

Space-filling model of protocatechuate 3,4-dioxygenase from P.putida. The alpha and beta chains of the individual protomers are shown in red and green, respectively.

Interactive figure of 3,4-PCD (requires Chime).

 

Selected Publications
  • Frazee, R. W., A. M. Orville, et al. (1998). “The axial tyrosinate Fe3+ ligand in protocatechuate 3,4-dioxygenase influences substrate binding and product release: evidence for new reaction cycle intermediates.” Biochemistry 37(8): 2131-44.
  • Orville, A. M., J. D. Lipscomb, et al. (1997). “Crystal structures of substrate and substrate analog complexes of protocatechuate 3,4-dioxygenase: endogenous Fe3+ ligand displacement in response to substrate binding.” Biochemistry 36(33): 10052-66.
  • Orville, A. M., N. Elango, et al. (1997). “Structures of competitive inhibitor complexes of protocatechuate 3,4- dioxygenase: multiple exogenous ligand binding orientations within the active site.” Biochemistry 36(33): 10039-51.
  • Ohlendorf, D. H., A. M. Orville, et al. (1994). “Structure of protocatechuate 3,4-dioxygenase from Pseudomonas aeruginosa at 2.15 Å resolution.” J Mol Biol 244(5): 586-608.
  • Ohlendorf, D. H., J. D. Lipscomb, et al. (1988). “Structure and assembly of protocatechuate 3,4-dioxygenase.” Nature 336(6197): 403-5.
  • Ohlendorf, D. H., P. C. Weber, et al. (1987). “Determination of the quaternary structure of protocatechuate 3,4- dioxygenase from Pseudomonas aeruginosa.” J Mol Biol 195(1): 225-7.