Complementation on ribosomes between aspartate transcarbamylase mutants of Neurospora

Issaly, A. S.; Cataldi, Susana A.; Issaly, Inda M.; Reissig, José L.

doi:10.1016/0005-2787(70)90747-1

Cited by 7 publications

(3 citation statements)

References 5 publications

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“…2B), and particles of precipitate could be associated with groups of ribosomes or of preribosomal components. An association of ATCase with ribosomes is consistent with in vitro studies of complementation of ATCase mutants that showed that ribosomes were the best complementing component (15). Spors and Merker (11) also showed a close relation of ATCase with ribosomes by histochemical tests.…”

Section: Resultssupporting

confidence: 65%

Carbamoyl Phosphate Compartmentation in Neurospora : Histochemical Localization of Aspartate and Ornithine Transcarbamoylases

Bernhardt

Davis

1972

Proc. Natl. Acad. Sci. U.S.A.

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Carbamoyl phosphate is required for arginine and pyrimidine synthesis. In the arginine pathway, it is used in the ornithine transearbamoylase (EC 2.1.2.1) reaction; in the pyrimidine pathway, it is used in the aspartate transcarbamoylase (EC 2.1.3.2) reaction. In Neurospora crassa, two pathway-specific enzymes catalyze the synthesis of carbamoyl phosphate, and two pathspecific pools of carbamoyl phosphate are maintained. Histochemical studies show-that ornithine transcarbamoylase is located in mitochondria, and, with less certainty, that aspartate transcarbamoylase is confined largely to nuclei. The enzymes that form carbamoyl phosphate are associated with the respective transcarbamoylases in the cell. Therefore, the segregation of carbamoyl phosphate pools could be accounted for by one or both organellar membranes, which demarcate two separate sites of carbamoyl phosphate metabolism in Neurospora. The alternative possibility that the enzyme complex that produces and consumes carbamoyl phosphate in the pyrimidine pathway could explain the channelling of carbamoyl phosphate, wholly or in part, is discussed.Nonrandom distribution of metabolites within cells as a factor in their metabolic fates is known as channelling. Several compounds involved in oxidative phosphorylation are confined to mitochondria, and certain enzyme aggregates appear to retain intermediates in the course of sequential reactions. The metabolism of carbamoyl phosphate (carbamoyl-P) in eukaryotes has recently been studied in relation to channelling (1-3). Carbam6yl-P is an intermediate of the arginine and pyrimidine pathways, used, respectively, by ornithine transcarbamoylase (OTCase: carbamoylphosphate: ornithine carbamoyltransferase, EC 2.1.3.1) and aspartate transcarbamoylase (ATCase: carbamoylphosphate: aspartate carbamoyltransferase, EC 2.1.3.2). Eukaryotes, in contrast to bacteria, have two enzymes for carbamoyl-P synthesis. In Neurospora crassa, both are glutamine-dependent carbamoyl-P synthetases (EC 2.7.2.5). Studies with mutants lacking one or the other of the synthetases show that one (carbamoyl-P synthetase A) has a specific role in the arginine pathway, while the other (carbamoyl-P synthetase P) functions solely in the pyrimidine pathway (1, 4, 5). These studies suggest that two discrete pools of carbamoyl-P are maintained, since mutants lacking one of the synthetases have an absolute and specific requirement for the corresponding end-product, either uridylic acid or arginine. More direct evidence that supports this view has been published (2).In mammals, it was established that citrulline synthesis (OTCase and carbamoyl-P synthetase I, which uses ammonia as an N donor) was largely a mitochondrial function (6, 7). Carbamoyl-P synthetase II and ATCase were apparently localized in the high-speed supernatant or light membrane fraction of mammalian tissues according to differential centrifugation studies (8). Recent histochemical localization of OTC in mitochondria (and possibly in the cytosol) of rat hepatocytes has been demons...

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Section: Resultssupporting

confidence: 65%

Carbamoyl Phosphate Compartmentation in Neurospora : Histochemical Localization of Aspartate and Ornithine Transcarbamoylases

Bernhardt

Davis

1972

Proc. Natl. Acad. Sci. U.S.A.

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“…Issaly et al (39) have made the interesting observation that complemen tation of Neurospora pyr-3 mutants defective in aspartate transcarbamylase occurs efficiently in a cell-free system including ribosomes of either mutant of a complementing pair with soluble protein from the other. Complementa tion apparently did not occur between ribosomes and ribosomes but only between ribosomes and soluble protein.…”

Section: Complementationmentioning

confidence: 98%

Fungal Genetics

Fincham

1970

Annu. Rev. Genet.

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A review under this extremely broad title must necessarily be somewhat selective, and I shall concentrate on two areas in which fungi have a special contribution to make. In the field of biochemical genetics fungi, though they have lagged somewhat behind bacteria, are by far the most amenable of the eukaryotes, and studies of genetic determination of protein structure and the regulation of protein synthesis in fungi are of special interest in connection with the question of how far extrapolation from prokaryotes to eukaryotes is justified. For studies on recombination, fungi are uniquely suitable since they combine many of the experimental advantages of bacteria with the op portunity for tetrad, or octad, analysis. In addition to reviewing these two fields I will also deal with some new developments in experimental genetic systems in fungi.Certain aspects of yeast biochemical genetics are being covered by Hartwell elsewhere in this volume, so there will be less emphasis on Sac charomyces in this review than would otherwise have been the case. How ever, information from yeast on genetic determination of primary protein structure and recombination will be dealt with here.

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“…Complementation among ACT-negative strains have, in fact, been reported in yeast (DUPHILDENIS and KAPLANreported by 0' DONOVAN and NEUHARD 1970) and Neurospora (WOODWARD 1962;ISSALY and REISSIG 1966). In the latter case complementation is possibly intercistronic (ISSALY et al 1970).…”

Section: Discussionmentioning

confidence: 99%

Interallelic complementation for pyrimidine requirement in rudimentary mutants of Drosophila melanogaster

2009

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Complementation at the rudimentary locus in Drosophila melanogaster is reported for the nutritional requirement observed earlier in the rudimentary mutants. It is demonstrated that this complementation parallels that for wing phenotype, and that at the same time it is a more potent and quantitative test for complementation at this locus. The possible molecular basis for the observed complementation is discussed in the light of current knowledge of the genetic regulation of pyrimidine biosynthesis in other organisms.

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Complementation on ribosomes between aspartate transcarbamylase mutants of Neurospora

Cited by 7 publications

References 5 publications

Carbamoyl Phosphate Compartmentation in Neurospora : Histochemical Localization of Aspartate and Ornithine Transcarbamoylases

Carbamoyl Phosphate Compartmentation in Neurospora : Histochemical Localization of Aspartate and Ornithine Transcarbamoylases

Fungal Genetics

Interallelic complementation for pyrimidine requirement in rudimentary mutants of Drosophila melanogaster

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