Nitrite reductase genetics

Jiingst, A., Braun, C., and Zumft, W. G. (1991a). Close linkage in Pseudomonas stutzeri of the structural genes for respiratory nitrite reductase and nitrous oxide reductase, and other essential genes for denitrification. Mol. Gen. Genet. 225, 241-248. 

Back, E., Burkhart, W., Moyer, M., Privalle, L. Rothstein, S. (1988). Isolation of cDNA clones coding for spinach nitrite reductase complete sequence and nitrate induction. Molecular and General Genetics 212, 20-6. 

The reduction of nitrate to ammonia is a rather simple chemical process under very complex control in biological systems. In higher plants the assimilation of nitrate involves the acquisition and subsequent reduction of nitrate to ammonia by nitrate and nitrite reductase. Although our understanding of the biochemistry, genetics, and molecular aspects of nitrate assimilation has advanced, a great deal remains to be learned, especially about regulation and... 

In summary, a considerable body of enzymatic, genetic, and analytical data supports the view that the major, if not sole, pathway of denitrification involves NO as an obligatory intermediate and requires the action of nitric oxide reductase. On the other hand, the ability of nitrite to modify nitrosyl transfer ratios and the N isotope fractionation factor during its reduction, are consistent with the reductive scheme of Averill and Tiedje (1982). It was suggested (Goretski... 

The hemoprotein fraction has no NADPH-dependent activities, but reduces sulfite in the presence of MVH. The flavoprotein fraction catalyzes electron transfer from NADPH to diaphorase-type acceptors and to acetylpyridine adenine dinucleotide phosphate. It does not reduce sulfite, nitrite, or hydroxylamine with either NADPH or MVH as electron donor. The molecular weight of the flavoprotein is estimated to be 470,000 (two-thirds of the whole enzyme). A similar flavoprotein with a molecular weight of 460,000 has been isolated from a S. typhimurium mutant, which requires cysteine for growth. Other genetic data on the S. typhimurium enzyme (394), which appears to be essentially identical to the E. coli sulfite reductase, are in agreement with the above results. Thus mutants lacking the flavoprotein or the hemoprotein component of the enzyme and containing only the appropriate partial activities have been obtained and the respective partial enzymes isolated. The absorption spectra of sulfite reductase preparations from the wild type and from these mutants are shown in Fig. 46, and the proposed structure for the two components of the wild-type enzyme is shown in Fig. 47. Reconstitution of NADPH-sulfite reductase by recombination of the flavoprotein... 

A condition described as "hereditary methemoglobinemia" may result from a genetic defect (Goldstein et al. 1969). The enzyme methemoglobin reductase is absent and persons are hypersensitive to any substances such as nitrite or aniline derivatives capable of producing methemoglobinemia. The trait is inherited as an autosomal recessive allele. Thus either sex may exhibit the trait which is ordinarily detected by the presence of cyanosis at birth. Such individuals would be extremely sensitive to the effects of nitrobenzene. 

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