Enzymatic and non-enzymatic reduction of nitrite by extracts of Neurospora crassa

Chang, Hsiao-Lin; Mulkins, G.; Dyer, June Carol; Sorger, George J.

doi:10.1128/jb.123.2.755-758.1975

Cited by 9 publications

(7 citation statements)

References 15 publications

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“…TABLE 5. Growth of the wild type and various mutants on several different nitrogen-containing media Urea, aspartic acid (Asp), or asparagine (Asn) was present at 50 mM in the growth medium as the sole source of nitrogen.…”

Section: Discussionmentioning

confidence: 99%

“…Extracts of some am mutants possess a cross-reacting material immunologically related to the wild-type NADPH-glutamate dehydrogenase (32), and two am mutants have been shown to produce aberrant NADPH-glutamate dehydrogenase with an altered amino acid sequence (4,41). The structural genes for nitrite reductase and NADH-glutamate dehydrogenase are not known in N. crassa, although a mutant lacking nitrite reductase activity has been reported (5).…”

Section: N03--n02--mentioning

confidence: 99%

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Regulation of Glutamate Dehydrogenases in nit-2 and am Mutants of Neurospora crassa

1979

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The regulation of the glutamate dehydrogenases was investigated in wild-type Neurospora crassa and two classes of mutants altered in the assimilation of inorganic nitrogen, as either nitrate or ammonium. In the wild-type strain, a high nutrient carbon concentration increased the activity of reduced nicotinamide adenine dinucleotide phosphate (NADPH)-glutamate dehydrogenase and decreased the activity of reduced nicotinamide adenine dinucleotide (NADH)glutamate dehydrogenase. A high nutrient nitrogen concentration had the opposite effect, increasing NADH-glutamate dehydrogenase and decreasing NADPHglutamate dehydrogenase. The nit-2 mutants, defective in many nitrogen-utilizing enzymes and transport systems, exhibited low enzyme activities after growth on a high sucrose concentration: NADPH-glutamate dehydrogenase activity was reduced 4-fold on NH4Cl medium, and NADH-glutamate dehydrogenase, 20-fold on urea medium. Unlike the other affected enzymes of nit-2, which are present only in basal levels, the NADH-glutamate dehydrogenase activity was found to be moderately enhanced when cells were grown on a low carbon concentration. This finding suggests that the control of this enzyme in nit-2 is hypersensitive to catabolite repression. The am mutants, which lack NADPH-glutamate dehydrogenase activity, possessed basal levels of NADH-glutamate dehydrogenase activity after growth on urea or L-aspartic acid media, like the wild-type strain, and possessed moderate levels (although threeto fourfold lower than the wild-type strain) on L-asparagine medium or L-aspartic acid medium containing NH4C1. These regulatory patterns are identical to those of the nit-2 mutants. Thus, the two classes of mutants exhibit a common defect in NADH-glutamate dehydrogenase regulation. Double mutants of nit-2 and am had lower NADH-glutamate dehydrogenase activities than either parent. A carbon metabolite is proposed to be the repressor of NADH-glutamate dehydrogenase in N. crassa.

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Section: Discussionmentioning

confidence: 99%

Section: N03--n02--mentioning

confidence: 99%

Regulation of Glutamate Dehydrogenases in nit-2 and am Mutants of Neurospora crassa

1979

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“…Decay of nitrate reductasie in the mutant nit-6. The N. crassa mutant nit-6 lacks nitrite reductase activity and consequently cannot utilize nitrate as a nitrogen source for growth (3). However, the nitrate reductase can be induced by transfer of ammonia-grown mycelia to media with nitrate for 4 h. Under these conditions, levels of nitrate reductase and CRM comparable to those in the wild type were found.…”

Section: Hou Rsmentioning

confidence: 97%

Repression of nitrate reductase activity and loss of antigenically detectable protein in Neurospora crassa

Amy¹,

Garrett²

1980

J Bacteriol

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Experiments were performed to determine whether conditions which cause the rapid loss of nitrate reductase activity in Neurospora crassa mycelia were accompanied by the loss of antigenically detectable nitrate reductase protein. When mycelia with nitrate reductase activity were transferred to ammonia media, there was a rapid loss in the reduced nicotinamide adenine dinucleotide-nitrate reductase activity plus the parallel loss of the reduced nicotinamide adenine dinucleotide-diaphorase and the reduced methyl viologen-nitrate reductase activities associated with the nitrate reductase. In addition, there was the loss of cross-reacting material to anti-nitrate reductase antisera that was concomitant with the loss of nitrate reductase activity. When mycelia were exposed to either ammonia plus cycloheximide, nitrate plus cycloheximide, or nitrogen-free media, or to media which lacked an assimilable carbon source, the amount of cross-reacting material declined in concert with the nitrate reductase activity. The mutant nit-6, which lacks nitrite reductase activity, was exposed to ammonia or nitrate plus cycloheximide media. The nitrate reductase and the amount of cross-reacting material declined together as in the wild-type mycelia. We conclude that the loss of nitrate reductase activity was accompanied by the specific loss of this protein and that no pool of inactivated nitrate reductase molecules existed.

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“…Enzyme preparation was as described previously (1). Nitrite reductase was assayed as described by Chang et al (1). One unit of nitrite reductase activity is defined as the reduction of 1 nmol of nitrite per min, and 1 unit of ammonia-producing activity is defined as the production of 1 nmol of ammonia per min.…”

mentioning

confidence: 99%

“…The mycelia were harvested, extracted, and assayed for nicotinamide adenine dinucleotide (NADPH) nitrate reductase activity. One-milliliter aliquots of extracts were used to determine the ammonia content by the Conway microdiffusion method and by using Nessler's reagent (1). The results on ammonia content are representative of two sets of determinations.…”

mentioning

confidence: 99%

Effect of Ammonium Ions on the Induction of Nitrite Reductase inNeurospora crassa

Chang

Sorger

1976

J Bacteriol

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Enzymatic and non-enzymatic reduction of nitrite by extracts of Neurospora crassa

Cited by 9 publications

References 15 publications

Regulation of Glutamate Dehydrogenases in nit-2 and am Mutants of Neurospora crassa

Regulation of Glutamate Dehydrogenases in nit-2 and am Mutants of Neurospora crassa

Repression of nitrate reductase activity and loss of antigenically detectable protein in Neurospora crassa

Effect of Ammonium Ions on the Induction of Nitrite Reductase inNeurospora crassa

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