Studies of the catabolic pathway of degradation of nitrobenzene by Pseudomonas pseudoalcaligenes JS45: removal of the amino group from 2-aminomuconic semialdehyde

Abstract

Pseudomonas pseudoalcaligenes JS45 utilizes nitrobenzene as the sole source of nitrogen, carbon, and energy. Previous studies have shown that degradation of nitrobenzene involves the reduction of nitrobenzene to nitrosobenzene and hydroxylaminobenzene, followed by rearrangement to 2-aminophenol, which then undergoes meta ring cleavage to 2-aminomuconic semialdehyde. In the present paper, we report the enzymatic reactions responsible for the release of ammonia after ring cleavage. 2-Aminomuconic semialdehyde was oxidized to 2aminomuconate in the presence of NAD by enzymes in crude extracts. 2-Aminomuconate was subsequently deaminated stoichiometrically to 4-oxalocrotonic acid. No cofactors are required for the deamination. Two enzymes, 2-aminomuconic semialdehyde dehydrogenase and a novel 2-aminomuconate deaminase, distinguished by partial purification of the crude extracts, catalyzed the two reactions. 4-Oxalocrotonic acid was further degraded to pyruvate and acetaldehyde. The key enzyme, 2-aminomuconate deaminase, catalyzed the hydrolytic deamination that released ammonia, which served as the nitrogen source for growth of the organism.

Toward Biorecycling: Isolation of a Soil Bacterium That Grows on a Polyurethane Oligomer and Monomer

“…Due to the low steric hindrance of an additional amino group substrate promiscuity might be favored. Enzymes involved in aromatics degradation exhibiting significant activity with substituted substrate analogs were reported before (Pascal and Huang, 1986;Smith et al, 1990;He and Spain, 1997;Eby et al, 2001;Chang et al, 2003;Guzik et al, 2011). However, the proposed degradation pathway of 2,4-TDA in the putative Pseudomonas strain TDA1 needs further confirmation via proteomic, transcriptomic analysis or in vitro assays with potential intermediates of the proposed pathway.…”

“…As the next step, the formed 4-amino-2-hydroxymuconate could be deaminated by an aminomuconate deaminase (candidate genes 14860 or 05035) similar to the deamination after ring cleavage in the degradation pathway of aminophenol in Pseudomonas sp. AP-3 (Takenaka et al, 2000) or in nitrobenzene degradation in Pseudomonas pseudoalcaligenes JS4 (He and Spain, 1997). For the latter, the enzyme 2-aminomuconate deaminase does not depend on cofactors and deamination of its substrate even happens spontaneously in acidic environments (Ichiyama et al, 1965).…”

Activated sludge and other suspended culture processes

“…Nitro-, Nitrate-, and Sulfate-Containing Organics. The catabolic pathways for nitrobenzene (He and Spain, 1997) and 3-nitrophenol (Schenzle et aI., 1997) were reported. The pure cultures studied used the nitroaromatic compound as a source of nitrogen, carbon, and energy.…”

A Novel 2-Aminomuconate Deaminase in the Nitrobenzene Degradation Pathway of Pseudomonas pseudoalcaligenes JS45

“…In our investigations of the biodegradation of nitrobenzene by Pseudomonas pseudoalcaligenes JS45, we found that 2-aminomuconate is one of the intermediates in the catabolic pathway (7). The compound, isolated by anion exchange chromatography, was hydrolytically deaminated to 4-oxalocrotonate by crude extracts of P. pseudoalcaligenes JS45 in a reaction similar to the first step in the hypothetical two-enzyme pathway of degradation of 2-aminomuconate in mammals.…”