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. 1967 Jul;104(1):103–111. doi: 10.1042/bj1040103

Genetic and biochemical studies of nitrate reduction in Aspergillus nidulans

J A Pateman 1,*, B M Rever 1,†, D J Cove 1
PMCID: PMC1270550  PMID: 4382427

Abstract

1. In Aspergillus nidulans nitrate and nitrite induce nitrate reductase, nitrite reductase and hydroxylamine reductase, and ammonium represses the three enzymes. 2. Nitrate reductase can donate electrons to a wide variety of acceptors in addition to nitrate. These artificial acceptors include benzyl viologen, 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride, cytochrome c and potassium ferricyanide. Similarly nitrite reductase and hydroxylamine reductase (which are possibly a single enzyme in A. nidulans) can donate electrons to these same artificial acceptors in addition to the substrates nitrite and hydroxylamine. 3. Nitrate reductase can accept electrons from reduced benzyl viologen in place of the natural donor NADPH. The NADPH–nitrate-reductase activity is about twice that of reduced benzyl viologen–nitrate reductase under comparable conditions. 4. Mutants at six gene loci are known that cannot utilize nitrate and lack nitrate-reductase activity. Most mutants in these loci are constitutive for nitrite reductase, hydroxylamine reductase and all the nitrate-induced NADPH-diaphorase activities. It is argued that mutants that lack nitrate-reductase activity are constitutive for the enzymes of the nitrate-reduction pathway because the functional nitrate-reductase molecule is a component of the regulatory system of the pathway. 5. Mutants are known at two gene loci, niiA and niiB, that cannot utilize nitrite and lack nitrite-reductase and hydroxylamine-reductase activities. 6. Mutants at the niiA locus possess inducible nitrate reductase and lack nitrite-reductase and hydroxylamine-reductase activities. It is suggested that a single enzyme protein is responsible for the reduction of nitrite to ammonium in A. nidulans and that the niiA locus is the structural gene for this enzyme. 7. Mutants at the niiB locus lack nitrate-reductase, nitrite-reductase and hydroxylamine-reductase activities. It is argued that the niiB gene is a regulator gene whose product is necessary for the induction of the nitrate-utilization pathway. The niiB mutants either lack or produce an incorrect product and consequently cannot be induced. 8. Mutants at the niiribo locus cannot utilize nitrate or nitrite unless provided with a flavine supplement. When grown in the absence of a flavine supplement the activities of some of the nitrate-induced enzymes are subnormal. 9. The growth and enzyme characteristics of a total of 123 mutants involving nine different genes indicate that nitrate is reduced to ammonium. Only two possible structural genes for enzymes concerned with nitrate utilization are known. This suggests that only two enzymes, one for the reduction of nitrate to nitrite, the other for the reduction of nitrite to ammonium, are involved in this pathway.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. COVE D. J., PATEMAN J. A. Independently segregating genetic loci concerned with nitrate reductase activity in Aspergillus nidulans. Nature. 1963 Apr 20;198:262–263. doi: 10.1038/198262a0. [DOI] [PubMed] [Google Scholar]
  2. Cove D. J., Coddington A. Purification of nitrate reductase and cytochrome c reductase from Aspergillus nidulans. Biochim Biophys Acta. 1965 Nov 22;110(2):312–318. doi: 10.1016/s0926-6593(65)80038-8. [DOI] [PubMed] [Google Scholar]
  3. Cove D. J. The induction and repression of nitrate reductase in the fungus Aspergillus nidulans. Biochim Biophys Acta. 1966 Jan 11;113(1):51–56. doi: 10.1016/s0926-6593(66)80120-0. [DOI] [PubMed] [Google Scholar]
  4. Darlington A. J., Scazzocchio C., Pateman J. A. Biochemical and genetical studies of purine breakdown in Aspergillus. Nature. 1965 May 8;206(984):599–600. doi: 10.1038/206599a0. [DOI] [PubMed] [Google Scholar]
  5. Englesberg E., Irr J., Power J., Lee N. Positive control of enzyme synthesis by gene C in the L-arabinose system. J Bacteriol. 1965 Oct;90(4):946–957. doi: 10.1128/jb.90.4.946-957.1965. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Ingle J. The regulation of activity of the enzymes involved in the assimilation of nitrate by higher plants. Biochem J. 1966 Sep;100(3):577–588. doi: 10.1042/bj1000577. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Joy K. W., Hageman R. H. The purification and properties of nitrite reductase from higher plants, and its dependence on ferredoxin. Biochem J. 1966 Jul;100(1):263–273. doi: 10.1042/bj1000263. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. LOWE R. H., EVANS H. J. PREPARATION AND SOME PROPERTIES OF A SOLUBLE NITRATE REDUCTASE FROM RHIZOBIUM JAPONICUM. Biochim Biophys Acta. 1964 Jun 1;85:377–389. doi: 10.1016/0926-6569(64)90301-3. [DOI] [PubMed] [Google Scholar]
  9. LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
  10. NASON A., EVANS H. J. Triphosphopyridine nucleotide-nitrate reductase in Neurospora. J Biol Chem. 1953 Jun;202(2):655–673. [PubMed] [Google Scholar]
  11. NICHOLAS D. J. THE METABOLISM OF INORGANIC NITROGEN AND ITS COMPOUNDS IN MICRO-ORGANISMS. Biol Rev Camb Philos Soc. 1963 Nov;38:530–568. doi: 10.1111/j.1469-185x.1963.tb00792.x. [DOI] [PubMed] [Google Scholar]
  12. PATEMAN J. A., COVE D. J., REVER B. M., ROBERTS D. B. A COMMON CO-FACTOR FOR NITRATE REDUCTASE AND XANTHINE DEHYDROGENASE WHICH ALSO REGULATES THE SYNTHESIS OF NITRATE REDUCTASE. Nature. 1964 Jan 4;201:58–60. doi: 10.1038/201058a0. [DOI] [PubMed] [Google Scholar]
  13. Sorger G. J. Nitrate reductase electron transport systems in mutant and in wild-type strains of Neurospora. Biochim Biophys Acta. 1966 Jun 15;118(3):484–494. doi: 10.1016/s0926-6593(66)80091-7. [DOI] [PubMed] [Google Scholar]

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