Effect of Ammonium Ions on the Induction of Nitrite Reductase in<i>Neurospora crassa</i>

Chang, Hsiao-Lin; Sorger, George J.

doi:10.1128/jb.126.2.1002-1004.1976

Cited by 13 publications

(3 citation statements)

References 12 publications

(11 reference statements)

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“…Used in a study showing glutamine to have a role as corepressor of uricase synthesis (1118). Used to study nitrogen assimilation and metabolism (503) and nitrogen metabolite repression (186,291). Efficient procedure for selecting new am mutants (551).…”

Section: Alx-1mentioning

confidence: 99%

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Chromosomal loci of Neurospora crassa

Perkins¹,

Radford²,

Newmeyer³

et al. 1982

Microbiol Rev

259

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I I ' ~~~~T h Ñ CiOr(r r N z ADDITIONAL LOCI IN LINKAGE GROUP ILinked to mt (8 to 12%) Linked to mt, acr-3 (5%) Right of arg-i (5/29) Linked to so and aro-8 Right of un-18 Between ad-5 and the centromere Between arg-i (4%) and his-3 (I to 2%) Between In(H4250) and T(39311) Left of mt (23%) Linked to mt (2%) and aza-i (39%o) Left of nit-2 (30%) Left of mt (14%) Linked to un-i (9%), probably to the right Linked to hom (1%), probably to the right Linked to mt (17 to 22%) Between T(NM103) and al-2 (18%) Between T(4540) and cr-2Between thi-i (12 to 20%/6) and ad-9 (5%) Linked to ad-5 (1/54), probably to the left Linked to mt (6%) Linked to cys-5 (<1%), probably to the right Right of ad-9 (12%), linked to al (0/76) Right of his-3 (2%) Between the T(AR173) breakpoints Linked to al-2 (10%) and nic-i (1 to 5%) Linked to ad-9 (0/44); right of thi-i (2%) Linked to mt (5%), probably to the left Linked to al-I (10%) Right of os-i (3%) Between nit,i (5 to 19%) and al-I (6 to 19%io) Linked near arg-i Left of al-2 (25%o) Left of mt (16%) Right of nic-2 (6%) Linked to ad-9 (2%), probably to the right Left of cr-i (15%) Left of mt (10%) Probably between his-2 (3%) and cr-i (3%) Between T(NM103) and the right tip Between mt (20%) and arg-i (1%) Between ad-3 (6%) and al-i (16%) Between his-3 and nic-2 Between cyh-i (5%) and al-I (7%) Linked to cyh-i (18%), al-i (2%), and mb-2 (6%) Between arg-i (3%) and T(39311) Between tre (41%) and ad-9 Linked to mt (9%) Linked to mt (20%) Complex phenotype. Alternative requirements: 2-acetylaminofluorine, certain azo dyes, or certain single amino acids. Cold sensitive. Originated among progeny of a rib-i strain that had become tolerant to 2-acetylaminofluorine.

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Section: Alx-1mentioning

confidence: 99%

“…Lacks nitrite reductase (185) (Fig. 19), which is subject to positive nitrogen metabolite repression (186). Affected by nit-2 and MS5 regulator genes (838, 1076a) (see nmr-1).…”

Section: Pb) (94)mentioning

confidence: 99%

Chromosomal loci of Neurospora crassa

Perkins¹,

Radford²,

Newmeyer³

et al. 1982

Microbiol Rev

259

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“…Dantzig et al (6) found that in a N. crassa mutant lacking NADP-glutamate dehydrogenase, ammonium was unable to repress the formation of nitrate reductase, although certain amino acids could still repress the enzyme. This observation led the authors to suggest that ammonium repression was, in fact, mediated by a nitrogen metabolite(s) other than ammonium ions, an idea that is not new (3,5,8). Studies in our laboratory with a glutamine auxotroph of N. crassa, identified glutamine (or a close metabolite of glutamine) as a corepressor of nitrate reductase (19).…”

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confidence: 99%

Repression of nitrate reductase in Neurospora studied by using L-methionine-DL-sulfoximine and glutamine auxotroph gln-1b

Premakumar¹,

Sorger²,

Gooden³

1980

J Bacteriol

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The effect of L-methionine-DL-sulfoximine, an inhibitor of glutamine synthetase, on the formation of nitrate reductase in the wild-type strain of Neurospora in the presence of ammonium ions and of glutamine was studied. Under conditions in which glutamine synthetase was inactivated, it was found that only glutamine could repress nitrate reductase. In a mutant of Neurospora, gln-lb, which requires glutamine for growth, only glutamine could repress nitrate reductase. These results suggest a direct role for glutamine as corepressor of nitrate reductase in Neurospora.Nitrate reductase from Neurospora crassa, the first enzyme in the assimilation of nitrate, is induced by nitrate (12,16,25) and repressed by ammonium (12,25,29) by what seems to be a form of nitrogen metabolite repression (1,20). The mechanism of "ammonium repression" of nitrate reductase in Neurospora has been the subject of several recent investigations (6,9,19). Dantzig et al. (6) found that in a N. crassa mutant lacking NADP-glutamate dehydrogenase, ammonium was unable to repress the formation of nitrate reductase, although certain amino acids could still repress the enzyme. This observation led the authors to suggest that ammonium repression was, in fact, mediated by a nitrogen metabolite(s) other than ammonium ions, an idea that is not new (3,5,8). Studies in our laboratory with a glutamine auxotroph of N. crassa, identified glutamine (or a close metabolite of glutamine) as a corepressor of nitrate reductase (19). Dunn-Coleman et al. (9) confirmed our results by a similar approach. They hypothesized that octameric glutamine synthetase, the predominant form of the enzyme under conditions of nitrogen sufficiency (9, 18), is the putative repressor.In the present study, the situation obtained in the glutamine auxotroph, namely the inability to convert ammonia to glutamine, is simulated in the wild-type strain by the use of L-methionine-DL-sulfoximine (MSX). This drug, long known to be an inhibitor ofglutamine synthetase (17), is phosphorylated on the enzyme to form methionine sulfoximine phosphate, which binds tightly to the active site (13,(21)(22)(23). The data indica,te that MSX inhibits the synthetase by acting as an analog of the tetrahedral intermediate or the transition state (15,23,30). In this study we attempt to demonstrate that when glutamine synthetase is inactivated in the above fashion, ammonium ions do not repress nitrate reductase in Neurospora, whereas glutamine still does repress the reductase. We also propose to demonstrate that in glutamine auxotropic Neurospora strain gln-lb glutamine represses the reductase.MATERIALS AND METHODS Neurospora strains. All strains except glutamine auxotroph gln-lb came from the fungal genetics stock center at Humboldt State University Foundation, Arcata, Calif. Strain 3-la (FGSC 935) was used as the wild-type strain. The mutant strain used was kindly provided by R. H. Garrett, University of Virginia, Charlottesville, Va. This mutant recently has been shown to have an impaired glutamine synthetase (7)...

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The role of glutamine synthetase and glutamine metabolism in nitrogen metabolite repression, a regulatory phenomenon in the lower eukaryote Neurospora crassa

Dunn-Coleman

Garrett

1980

Molec. Gen. Genet.

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Growth of Neurospora crassa on media containing NH4+ leads to the repression of a variety of permeases and alternative pathways which would generate NH4+, so called "ammonium repression." The mutant am2 which lacks NADP-GDH is not subject to ammonium repression of nitrate reductase or urea permease, but like the wild type has repressed levels of these systems when grown in the presence of proline, glutamate or glutamine. The glutamine synthetase (GS) mutant gln-1a has derepressed levels of the aforementioned systems unless grown with glutamine. The oligomeric state of GS depends upon the nitrogen sufficiency of the cell, a tetrameric form predominates under conditions of nitrogen limitation and an octameric form under conditions of nitrogen sufficiency. We have found that the tetrameric form GS predominates in the mutants am2 and gln-1a when they are ammonium derepressed. Th mechanism of NH4+ repression in N. crassa is thought to entail a cessation of positive gene action by the product of the nit-2 regulatory gene. We propose that under conditions of NH4+ sufficiency, and hence glutamine sufficiency, the octameric form of GS represses nit-2 gene expression and thereby achieves ammonium repression.

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

Abstract: Results with strain am-la, a glutamate dehydrogenaseless mutant, showed that ammonium ions must first be metabolized in order to repress nitrite reductase in Neurospora.

Cited by 13 publications

References 12 publications

Chromosomal loci of Neurospora crassa

Chromosomal loci of Neurospora crassa

Repression of nitrate reductase in Neurospora studied by using L-methionine-DL-sulfoximine and glutamine auxotroph gln-1b

The role of glutamine synthetase and glutamine metabolism in nitrogen metabolite repression, a regulatory phenomenon in the lower eukaryote Neurospora crassa

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