This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: p-nitrobenzoate degradation
|Superclasses:||Degradation/Utilization/Assimilation → Aromatic Compounds Degradation → Nitroaromatic Compounds Degradation → Nitrobenzoate Degradation|
Expected Taxonomic Range: Proteobacteria
Nitroaromatic compounds such as nitrophenols, nitrotoluenes and nitrobenzoates, are used in the synthesis of pesticides, plasticizers, dyes, pharmaceuticals, and explosives. These compounds are contaminants of waste waters, rivers and groundwater, and of the atmosphere [Leuenberger88]. In most cases nitroaromatic compounds are highly toxic to living organisms, and several of them have been listed as priority pollutants by the U.S. Environmental Protection Agency [Callahan79].
Despite their toxicity, these compounds can be degraded by several microorganisms. These degradation pathways almost always start with the removal or replacement of the nitro group [MarvinSikkema94]. The mechanisms in which bacteria are able to remove the nitro group can be divided into two broad categories - oxidative and reductive. In oxidative pathways the nitro group is released in the form of nitrite, usually catalyzed by a mono- or di-oxygenase enzymes. For examples, see 2-nitrotoluene degradation and 4-Nitrotoluene Degradation. In reductive pathways the nitro group is reduced via a nitroso intermediate to a hydroxylamino group, and sometime further to an amino group, and is released in the form of ammonia. For examples see 4-nitrotoluene degradation II and 4-nitrobenzoate degradation.
About This Pathway
Several bacterial strains are capable of utilizing 4-nitrobenzoate as the sole source of carbon and energy. The degradation of 4-nitrobenzoate was first demonstrated for a Delftia acidovorans strain [Groenewegen92]. This process proceeds through partial reduction of the nitro group prior to its release as ammonia.
The first enzyme of this pathway, 4-nitrobenzoate reductase, catalyzes the transformation of 4-nitrobenzoate to 4-hydroxylaminobenzoate. The hydroxylamino group is subsequently removed from the aromatic ring as ammonia through the action of a 4-hydroxylaminobenzoate lyase with the concomitant formation of protocatechuate. This reductive pathway for 4-nitrobenzoate degradation has also been shown in Ralstonia pickettii [Yabannavar95] and in several strains of Pseudomonas putida which degrade 4-nitrotoluene [RhysWilliams93, Haigler93].
Callahan79: Callahan, M. A., Slimak, M. W., Gabel, N. W., May, J. P., Fowler, C. F., Freed, J. R., Jennings, P., Durfee, R. L., Whitmore, F. C., Maestri, B., Mabey, W. R., Holt, B. R., Gould, C. (1979). "Water-related environmental fate of 129 priority pollutants." EPA report-440/4-79-029b. U.S. Environmental Protection Agency, Washington, D.C.
Groenewegen92: Groenewegen PE, Breeuwer P, van Helvoort JM, Langenhoff AA, de Vries FP, de Bont JA (1992). "Novel degradative pathway of 4-nitrobenzoate in Comamonas acidovorans NBA-10." J Gen Microbiol 138 ( Pt 8);1599-605. PMID: 1527502
Yabannavar95: Yabannavar AV, Zylstra GJ (1995). "Cloning and characterization of the genes for p-nitrobenzoate degradation from Pseudomonas pickettii YH105." Appl Environ Microbiol 61(12);4284-90. PMID: 8534095
Hughes01a: Hughes MA, Williams PA (2001). "Cloning and characterization of the pnb genes, encoding enzymes for 4-nitrobenzoate catabolism in Pseudomonas putida TW3." J Bacteriol 2001;183(4);1225-32. PMID: 11157934
Lim02a: Lim EK, Doucet CJ, Li Y, Elias L, Worrall D, Spencer SP, Ross J, Bowles DJ (2002). "The activity of Arabidopsis glycosyltransferases toward salicylic acid, 4-hydroxybenzoic acid, and other benzoates." J Biol Chem 277(1);586-92. PMID: 11641410
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