Biodegradation of Nitroaromatic Compounds.
Final rept. 1 Nov 92-31 Oct 95,
IOWA UNIV IOWA CITY DEPT OF MICROBIOLOGY
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Pseudomonas sp. strain Js42 catalyzes the oxidative removal of nitrite from 2-nitro- toluene to form 3-methylcatechol. This reaction is catalyzed by a multicomponent enzyme system designated 2-nitrotoluene 2,3-dioxygenase. The ferredoxin 2NT component of the dioxygenase system was purified and characterized. It is a Rieske 2Fe-2S protein with properties similar to the isofunctional ferredoxins in other multicomponent dioxygenase systems. The genes encoding the reductase, ferredoxin and terminal oxygenase components of 2-nitrotoluene dioxygenase were cloned and their nucleotide sequences determined. The predicted amino acid sequences of the thee protein components showed significant identity to the sequences of the isofunctional components in naphthalene dioxygenase. However, there were significant differences in the substrate specificities of the two enzymes. The gene encoding catechol 2,3- dioxygenase in a nitrobenzene-degrading Comamonas strain was cloned and expressed in H. Coli. The results to date represent the first purification and characterization of an enzyme system that can oxidatively remove nitro substituents from the benzene nucleus.
- Inorganic Chemistry