Affiliation:
1. Institute for Aquatic Sciences and Water Pollution Control, Swiss Federal Institute of Technology, Zurich ETHZ.
Abstract
The initial step in the anoxic metabolism of nitrilotriacetate (NTA) was investigated in a denitrifying member of the gamma subgroup of the Proteobacteria. In membrane-free cell extracts, the first step of NTA oxidation was catalyzed by a protein complex consisting of two enzymes, NTA dehydrogenase (NTADH) and nitrate reductase (NtR). The products formed were iminodiacetate and glyoxylate. Electrons derived from the oxidation of NTA were transferred to nitrate only via the artificial dye phenazine methosulfate, and nitrate was stoichiometrically reduced to nitrite. NTADH activity could be measured only in the presence of NtrR and vice versa. The NTADH-NtrR enzyme complex was purified and characterized. NTADH and NtrR were both alpha 2 dimers and had molecular weights of 170,000 and 105,000, respectively. NTADH contained covalently bound flavin cofactor, and NtrR contained a type b cytochrome. Optimum NTA-oxidizing activity was achieved at a molar ratio of NTADH to NtrR of approximately 1:1. So far, NTA is the only known substrate for NTADH. This is the first report of a redox enzyme complex catalyzing the oxidation of a substrate and concomitantly reducing nitrate.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Reference58 articles.
1. A review of the environmental and mammalian toxicology of nitrilotriacetic acid;Anderson R. L.;Crit. Rev. Toxicol.,1985
2. Bacterial electron transport. Annu;Anraku Y.;Rev. Biochem.,1988
3. Anthony C. 1988. Quinoproteins and energy transduction p. 293-316. In C. Anthony (ed.) Bacterial energy transduction. Academic Press London.
4. Description of the Gram-negative, obligately aerobic, nitrilotriacetate (NTA)-utilizing bacteria as Chelatobacter heintzii, gen. nov., sp. nov., and Chelatococcus asaccharovorans, gen. nov., sp. nov;Auling G.;Syst. Appl. Microbiol.,1993
5. Bernhardt H. W. Berth U. Forster A. Hamm W. Janicke J. Kandler S. Kanowski H. H. Kleiser P. Koppe H. J. Opgenorth J. K. Reichert and H. Stehfest. 1984. NTA: Studie uber die aquatische Umweltvertraglichkeit von Nitrilotriacetat (NTA). Hans Richarz Sankt Augustin Germany.
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