Demonstration in vitro of two intracellular inactivators of nitrate reductase from Neurospora

Sorger, George J.; Premakumar, R.; Gooden, Dinsdale

doi:10.1016/0304-4165(78)90432-4

Cited by 23 publications

(9 citation statements)

References 44 publications

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“…4) is also a negative feedback loop, which, like in higher plants and algae, may be capable of acting as an autonomous daily rhythm generator. The inactivation and turnover of Neurospora NR and its mRNA have been found to be fairly rapid processes (Okamoto et al, 1991;Sorger et al, 1978;Walls et al, 1978). As for the FRQ negative feedback loop (Ruoff et al, 1999), the degradation of NR and its mRNA may play a role in defining the period length of the NR oscillator and its temperature behavior.…”

Section: Resultsmentioning

confidence: 99%

A Nitrate-Induced frq-Less Oscillator in Neurospora crassa

et al. 2004

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When nitrate is the only nitrogen source, Neurospora crassa's nitrate reductase (NR) shows endogenous oscillations in its nitrate reductase activity (NRA) on a circadian time scale. These NRA oscillations can be observed in darkness or continuous light conditions and also in a frq 9 mutant in which no functional FRQ protein is formed. Even in a white-collar-1 knockout mutant, NRA oscillations have been observed, although with a highly reduced amplitude. This indicates that the NRA oscillations are not a simple output rhythm of the whitecollar-driven frq oscillator but may be generated by another oscillator that contains the nit-3 autoregulatory negative feedback loop as a part. In this negative feedback loop, a product in the reaction chain catalyzed by nitrate reductase, probably glutamine, induces repression of the nitrate reductase gene and thus downregulates its own production. This is the first example of an endogenous, nutritionally induced daily rhythm with known molecular components that is observed in the absence of an intact FRQ protein.

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Section: Resultsmentioning

confidence: 99%

A Nitrate-Induced frq-Less Oscillator in Neurospora crassa

et al. 2004

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“…This effect can be prevented by protein synthesis inhibitors (LEWIS andFINCHAM 1970, GOLDSMITH et al 1973). This suggests the involvement of special proteins in the enzyme decay, probably proteolytic inactivators (SORGER et al 1978). In Neurospora, the repression of nitrate reductase seems to be not due to ammonia itself but to glutamine (PREMAKUMAR et al 1979).…”

Section: Uptake and Reduction Of Nitrate And Nitrite In Fungimentioning

confidence: 97%

Uptake and Reduction of Nitrate: Algae and Fungi

Ullrich¹

1983

Inorganic Plant Nutrition

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“…Recently, Sorger et al (19) and Walls et al (26) reported the isolation and characterization of two NR inactivators from Neurospora crassa (inactivator I and inactivator II). These factors differ markedly in pH optimum and sensitivity to EDTA, PMSF, cycloheximide, and heat treatment.…”

Section: Discussionmentioning

confidence: 99%

In Vitro Stability of Nitrate Reductase from Wheat Leaves

Sherrard¹,

Kennedy²,

Dalling³

1979

Plant Physiol.

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A nitrate reductase (EC 1.6.6.1)-inactivating factor has been isolated from 8-day-old wheat leaves. The purification schedule involved ammonium sulfate precipitation, Sephadex G-100 filtration, DEAE-cellulose chromatography, and Sephadex G-150 filtration. No accurate assessment could be made as to the degree of purification relative to crude extract as the inactivating factor could not be detected in crude extract. However a 2,446-fold purification was achieved from the ammonium sulfate fraction to the pooled enzyme from the Sephadex G-150 step.The inactivating factor was heat-labile and had a molecular weight of 37,500. The inactivating factor was particularly sensitive to the divalent metal chelators, 1,10-phenanthroline and bathophenanthroline. Evidence indicated that Fe2" may be the functional metal. The trypsin inhibitors Na-p-tosyl-L-lysine chloromethyl ketone and a-N-benzoyl-L-arginine were inhibitory. However, phenylmethyl sulfonyl fluoride, an inhibitor of serine peptide hydrolases, was not inhibitory. Neither casein nor hemoglobin nor a range of artificial substrates were hydrolyzed by the inactivating factor.Highly purified wheat leaf nitrite reductase (EC 1.7.993) and ribulose 1,5-bisphosphate carboxylase:oxygenase (EC 4.1.139) were not affected by the nitrate reductase-inactivating factor.The inactivating factor was more active toward the NADH-nitrate reductase compared to either of the component enzymic activities flavin adenine mononucleotide-nitrate reductase and methyl viologen-nitrate reductase. The NADH-ferricyanide reductase (diaphorase) component was the least sensitive.In a previous paper (17) we reported on the occurrence in crude extracts from wheat leaves (Triticum aestivum L.) of two types of factors which appeared to affect the in vitro stability of highly purified nitrate reductase. One of these factors (II) reduced the stability of NR3 while the other factors (I and III) seemed to confer stability on NR.

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Demonstration in vitro of two intracellular inactivators of nitrate reductase from Neurospora

Cited by 23 publications

References 44 publications

A Nitrate-Induced frq-Less Oscillator in Neurospora crassa

A Nitrate-Induced frq-Less Oscillator in Neurospora crassa

Uptake and Reduction of Nitrate: Algae and Fungi

In Vitro Stability of Nitrate Reductase from Wheat Leaves

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