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.
|Superclasses:||Degradation/Utilization/Assimilation → Carboxylates Degradation|
The metal chelating agents nitrilotriacetate and EDTA are aminopolycarboxylic acids. They are widely used industrially and can be found in natural waters and wastewaters. Copper-nitrilotriacetate and ferric-nitrilotriacetate complexes have been shown to be carcinogenic [Giri99, Iqbal07] . Bacterial strains that can degrade these compounds have been reported and are of interest as biodegradation agents. Because these compounds occur in the environment mostly as metal ion complexes, the influence of metal ion type on the degradation process is also of interest (reviewed in [Egli01]).
Bacterial strains capable of degrading nitrilotriacetate and EDTA have been isolated. Earlier work identified a pseudomonad that could aerobically degrade nitrilotriacetate and its metal ion complexes [Cripps73, Firestone75, Firestone78]. More recently, nitrilotriacetate degradation in Aminobacter aminovorans (previously named Chelobacter heintzii ATCC 29600), a Gram-negative, obligately aerobic bacterium, has been well studied. The two key enzymes in aerobic nitrilotriacetate degradation are a monooxygenase and a membrane-bound dehydrogenase (in [Yuan08] and reviewed in [Egli01] and [BucheliWitschel01]). These enzymes are only expressed when cells are grown on nitrilotriacetate or iminodiacetate [Uetz93]. In addition, a bacterial strain that can degrade nitrilotriacetate anaerobically under denitrifying conditions has been isolated. It was described as a member of the gamma subgroup of the Proteobacteria and it utilized a nitrilotriacetate dehydrogenase [Wanner90, JenalWanner93]. Interestingly, a thermotolerant yeast, Kluyveromyces marxianus IMB3, was shown to be capable of using either nitrilotriacetate or iminodiacetate as a sole source of nitrogen for growth, and both nitrilotriacetate monooxygenase and iminodiacetate dehydrogenase enzyme activities were found in cell extracts of this yeast [Ternan02].
About This Pathway
The mechanism of transport of nitrilotriacetate, or its metal ion complexes into bacterial cells remains to be investigated. After oxidation and dehydrogenation, the products of the pathway, glyoxylate and glycine, undergo mineralization through as yet undefined steps (reviewed in [Egli01]). The dehydrogenase was shown to be an integral membrane protein, with its activity linked to the respiratory chain [Uetz93].
Unification Links: Eawag-BBD-Pathways:nta
Giri99: Giri U, Iqbal M, Athar M (1999). "Copper-nitrilotriacetate (Cu-NTA) is a potent inducer of proliferative response both in liver and kidney but is a complete renal carcinogen." Int J Oncol 14(4);799-806. PMID: 10087332
Iqbal07: Iqbal M, Okazaki Y, Okada S (2007). "Probucol modulates iron nitrilotriacetate (Fe-NTA)-dependent renal carcinogenesis and hyperproliferative response: diminution of oxidative stress." Mol Cell Biochem 304(1-2);61-9. PMID: 17487455
JenalWanner93: Jenal-Wanner U, Egli T (1993). "Anaerobic degradation of nitrilotriacetate (NTA) in a denitrifying bacterium: purification and characterization of the NTA dehydrogenase-nitrate reductase enzyme complex." Appl Environ Microbiol 59(10);3350-9. PMID: 8250558
Wanner90: Wanner U, Kemmler J, Weilenmann HU, Egli T, el-Banna T, Auling G (1990). "Isolation and growth of a bacterium able to degrade nitrilotriacetic acid under denitrifying conditions." Biodegradation 1(1);31-41. PMID: 1368140
Knobel96: Knobel HR, Egli T, van der Meer JR (1996). "Cloning and characterization of the genes encoding nitrilotriacetate monooxygenase of Chelatobacter heintzii ATCC 29600." J Bacteriol 178(21);6123-32. PMID: 8892809
Uetz92: Uetz T, Schneider R, Snozzi M, Egli T (1992). "Purification and characterization of a two-component monooxygenase that hydroxylates nitrilotriacetate from "Chelatobacter" strain ATCC 29600." J Bacteriol 174(4);1179-88. PMID: 1735711
Xu97: Xu Y, Mortimer MW, Fisher TS, Kahn ML, Brockman FJ, Xun L (1997). "Cloning, sequencing, and analysis of a gene cluster from Chelatobacter heintzii ATCC 29600 encoding nitrilotriacetate monooxygenase and NADH:flavin mononucleotide oxidoreductase." J Bacteriol 179(4);1112-6. PMID: 9023192
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