| Nitroaromatic compounds are an important class of xenobiotic chemicals, used in the production of dyes, explosives, herbicides, and pesticides. These compounds are also toxic, mutagenic, and highly stable. Although nitroaromatic compounds are new to the environment, bacterial strains have evolved oxidative pathways to mineralize these compounds to carbon dioxide and nitrite. The oxidative degradation of nitroaromatic compounds is initiated through ring dihydroxylation, where a Rieske-type non-heme dioxygenases catalyzes the addition of both atoms of molecular oxygen to the aromatic ring, releasing nitrite. The resulting catechol is degraded via a standard meta cleavage pathway. This review will discuss dioxygenation-based pathways for nitroaromatic compound degradation, as well as dioxygenase structure, substrate specificity, and genetics. Additionally, this review will discuss uses for dioxygenases in basic and applied science, including as a model for enzyme evolution and in bioremediation and biosensor development. |
