Arginaseless
            <i>Neurospora</i>
            : Genetics, Physiology, and Polyamine Synthesis

Davis, Rowland H.; Lawless, Mary B.; Port, Loretta A.

doi:10.1128/jb.102.2.299-305.1970

Cited by 81 publications

(43 citation statements)

References 20 publications

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“…Knockout strains of hH1 were generated by the Neurospora gene knockout consortium (Colot et al 2006) and obtained from the Fungal Genetics Stock Center (McCluskey et al 2010). Neurospora cultures were grown at 32°in Vogel's minimal medium (VMM) + 1.5% sucrose (Davis et al 1970). Crosses were performed on modified synthetic cross medium at 25° (Davis et al 1970).…”

Section: Strains Growth Media and Molecular Analysesmentioning

confidence: 99%

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Histone H1 limits DNA methylation inNeurospora crassa

Seymour

Santos

et al. 2016

Preprint

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Histone H1 variants, known as linker histones, are essential chromatin components in higher eukaryotes, yet compared to the core histones relatively little is known about their in vivo functions. The filamentous fungus Neurospora crassa encodes a single H1 protein that is not essential for viability. To investigate the role of N. crassa H1, we constructed a functional FLAG-tagged H1 fusion protein and performed genomic and molecular analyses. Cell fractionation experiments showed that H1-3XFLAG is a chromatin binding protein. Chromatin-immunoprecipitation combined with sequencing (ChIP-seq) revealed that H1-3XFLAG is globally enriched throughout the genome with a subtle preference for promoters of expressed genes. In mammals, the stoichiometry of H1 impacts nucleosome repeat length. To determine if H1 impacts nucleosome occupancy or nucleosome positioning in N. crassa, we performed micrococcal nuclease digestion in the wild-type and the DhH1 strain followed by sequencing (MNase-seq). Deletion of hH1 did not significantly impact nucleosome positioning or nucleosome occupancy. Analysis of DNA methylation by whole-genome bisulfite sequencing (MethylC-seq) revealed a modest but global increase in DNA methylation in the DhH1 mutant. Together, these data suggest that H1 acts as a nonspecific chromatin binding protein that can limit accessibility of the DNA methylation machinery in N. crassa.

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Section: Strains Growth Media and Molecular Analysesmentioning

confidence: 99%

“…Neurospora cultures were grown at 32°in Vogel's minimal medium (VMM) + 1.5% sucrose (Davis et al 1970). Crosses were performed on modified synthetic cross medium at 25° (Davis et al 1970). For plating assays, Neurospora conidia were plated on VMM with 2.0% sorbose, 0.5% fructose, and 0.5% glucose.…”

Section: Strains Growth Media and Molecular Analysesmentioning

confidence: 99%

Histone H1 limits DNA methylation inNeurospora crassa

Seymour

Santos

et al. 2016

Preprint

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“…Reduced growth rates did not appear to be responsible for the lowered enzyme levels since mycelia grown on arginine as a sole nitrogen source had a reduced growth rate, but the argiiine-degradative enzymes were maximally induced ( Table 1). The results did not appear to be due to inducer exclusion, since no significant differences were observed in the arginine pool (arginine has been shown to be the inducer of arginase and ornithine transaminase [12]).…”

Section: Resultsmentioning

confidence: 84%

Effect of Carbon Source on Enzymes and Metabolites of Arginine Metabolism in Neurospora

Drainas

Weiss

1980

J Bacteriol

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90024The levels of enzymes and metabolites of arginine metabolism were determined in exponential cultures of Neurospora crassa grown on various carbon sources. The carbon sources decreased in effectiveness (as determined by generation times) in the following order: sucrose, acetate, glycerol, and ethanol. The basal and induced levels of the catabolic enzymes, arginase (EC 3.5.3.1) and ornithine transaminase (EC 2.6.1.13), were lower in mycelia grown on poor carbon sources. Arginase was more sensitive to variations in carbon source than was ornithine transaminase. Induction of both enzymes was sensitive to nitrogen metabolite control, but this sensitivity was reduced in mycelia grown on glycerol or ethanol. The pools of arginine and ornithine were reduced in mycelia grown in unsupplemented medium containing poor carbon sources, but the biosynthetic enzyme ornithine transcarbamylase (EC 2.1.3.3) was not derepressed. The arginine pools were similar, regardless of carbon source, in mycelia grown in arginine-supplemented medium. The ornithine pool was reduced by growth on poor carbon sources. The rate of arginine degradation was proportional to the level of arginase in both sucroseand glycerol-grown mycelia. The distribution of arginine between cytosol and vesicles was only slightly altered by growth on glycerol instead of sucrose. The slightly smaller cytosolic arginine concentration did not appear to be sufficient to account for the alterations in basal and induced enzyme levels. The results suggest a possible carbon metabolite effect on the expression or turnover of a variety of genes for enzymes of arginine metabolism in Neurospora.The metabolism of amino acids in most organisms includes biosynthesis, degradation, and incorporation into protein. In Neurospora crassa, control of arginine metabolism includes mechanisms observed in many procaryotes but also some which appear to occur exclusively in eucaryotes (reviewed in reference 10). The better understood mechanisms include: (i) feedback inhibition by arginine of acetylglutamate kinase (EC 2.7.2.8), the second enzyme in the biosynthetic pathway (8); (ii) repression of carbamyl phosphate synthetase (EC 2.7.2.5) by arginine; (iii) induction of arginase and ornithine transaminase by arginine; and (iv) nitrogen control in which the induction of the catabolic enzymes is impaired by the end products of arginine catabolism (ammonia, glutamate, or glutamine).Two additional but poorly understood features also appear to contribute to the control of arginine metabolism in N. crassa. The first is a control system which has been termed cross pathway regulation and appears to involve a common regulatory element affecting the level of enzymes of arginine, histidine, lysine, and tryptophan metabolism (4, 5). A similar control system has been observed in Saccharomyces cerevisiae (25). The second feature, compartmentation of enzymes and metabolites, has been shown to affect arginine metabolism in N. crassa (10). In procaryotic cells, where less subcellular organization exists, most...

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“…Sensitivity of ornithine synthesis to exogenous arginine. Ornithine is the sole source of polyamines in N. crassa (12). The latter are required for normal germination and growth.…”

Section: Resultsmentioning

confidence: 99%

Isolation and characterization of Neurospora crassa mutants impaired in feedback control of ornithine synthesis

Weiss¹,

Lee²

1980

J Bacteriol

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Thirty-two independent mutants were isolated which overcame the proline requirement of pro-3 mutations in Neurospora crassa. The mutations were not revertants, appeared to be allelic, were closely linked or allelic to arg-6, and in strains unable to degrade ornithine no longer suppressed the proline requirement. The suppressor mutations did not alter the levels of biosynthetic or catabolic enzymes, yet allowed accumulation of ornithine. Suppressed strains unable to degrade arginine still produced ornithine (as detected by growth) in argininesupplemented medium. The results suggest that the suppressor mutants were impaired in the feedback inhibition of ormithine synthesis by arginine. The activity of the appropriate biosynthetic enzyme was less sensitive to inhibition by arginine. The potential usefulness of such mutations is discussed.

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Arginaseless Neurospora : Genetics, Physiology, and Polyamine Synthesis

Cited by 81 publications

References 20 publications

Histone H1 limits DNA methylation inNeurospora crassa

Histone H1 limits DNA methylation inNeurospora crassa

Effect of Carbon Source on Enzymes and Metabolites of Arginine Metabolism in Neurospora

Isolation and characterization of Neurospora crassa mutants impaired in feedback control of ornithine synthesis

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