Ornithine transcarbamylase from Neurospora crassa: Purification and properties

Bates, Marjorie; Weiss, Richard L.; Clarke, Steven

doi:10.1016/0003-9861(85)90824-0

Cited by 12 publications

(5 citation statements)

References 31 publications

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“…The pH optima are 0.5 U less for both enzymes in a partially purified state (e.g., 47,127). The K,,,s for ornithine and carbamoyl phosphate are higher at the optimal pH values than at lower pH values, and these values too vary greatly (0.1 to 5.0 mM for ornithine; 0.02 to 2.5 mM for carbamoyl phosphate) with the state of purity of the enzymes (5,47,83). However, the ornithine carbamoyltransferase of S. cer-evisiae displays ornithine substrate inhibition above 5 mM (83,164).…”

Section: Conversion Of Ornithine To Argininementioning

confidence: 97%

“…Ornithine carbamoyltransferases of N. crassa and S. cereviisiae are trimers of -37-kDa subunits and have estimated native molecular weights of -110,000 (5,190). The S. cerevisiaie ARG3 gene has been sequenced, and the deduced molecular weight of the product is 37,842 (R. Huygen and M. Crabeel, personal communication).…”

Section: Conversion Of Ornithine To Argininementioning

confidence: 99%

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Compartmental and regulatory mechanisms in the arginine pathways of Neurospora crassa and Saccharomyces cerevisiae.

Davis¹

1986

Microbiological Reviews

136

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Arginine metabolism has been studied intensively in manly organisms, beginning in earnest with the discovery of the urea cycle in mammals (139). The genetic control of the arginine pathway was the earliest example of the one-gene, one-enzyme relationship in the biochemical genetics of Neiurosporca crassa (206). The elucidation of the pathway in Escherichia coli followed soon thereafter, the term "repression'' having been coined to describe the regulatory behavior of acetylornithinase (229). The discovery of carbamoyl phosphate in 1955 (131) led to many comparative studies of its metabolism (52, 130, 152). A profound knowledge of arginine metabolism in N. crassa and Sacclhiaonvces (ceev'isiae has developed in the last 25 years. The subject justifies a comparative review, because the two organisms solve similar metabolic problems in different ways. It is likely that the fundamental phenomena of compartmentation and regulation in the two organisms can be seen throughout the evolutionary tree, used variously according to the demands of particular lifestyles. The synthesis of arginine in fungi has three main components: the synthesis of ornithine, the synthesis of carbamoyl phosphate, and the conversion of these two compounds to arginine. The catabolic pathway consists of the hydrolysis of arginine to ornithine and urea, the breakdown of urea to ammonia and carbon dioxide, and the conversion of ornithine to glutamate. A theme to be pursued is how the anabolic and catabolic pathways can each proceed to the exclusion of the other, given ornithine as a common intermediate. A related theme is how carbamoyl phosphate and ornithine are confined to the arginine pathway in the face of enzymes that might divert them to other fates. Both of these matters involve the compartmentation of small molecules by intracellular membranes, which in S. (ereiisiae is supplemented by elaborate enzyme regulatory mechanisms. This review describes the enzymology, genetics, and localization of the arginine enzymes of S. cere\eisiae and N. crassa. This is followed by descriptions of vacuolar function, enzyme regulation, and the integration of relevant factors in adaptation to different environments. Metabolic maps (Fig. 1 and 2) and a gene-enzyme directory (Table 1) are given for N. crassa(and S. cerevisiae. Arginine metabolism in these organisms has been reviewed in more limited ways previously (1

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Section: Conversion Of Ornithine To Argininementioning

confidence: 97%

Section: Conversion Of Ornithine To Argininementioning

confidence: 99%

Compartmental and regulatory mechanisms in the arginine pathways of Neurospora crassa and Saccharomyces cerevisiae.

Davis¹

1986

Microbiological Reviews

136

View full text Add to dashboard Cite

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“…is a multimeric enzyme. It is a protein well preserved during evolution in different species [11][12][13][14]. The enzyme (M w 120,000) has a trimeric structure composed of identical subunits, catalyzes the synthesis of citrulline from ornithine and carbamoyl phosphate with the release of orthophosphate during the first step in the de novo biosynthesis of arginine [13].…”

Section: Introductionmentioning

confidence: 99%

Influences of temperature and threshold effect of NaCl concentration on Alpias vulpinus OCT

Bellocco

Barreca

Laganà

et al. 2008

International Journal of Biological Macromolecules

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“…The OTC gene [NM_000531] at Xp11.4 encodes OTC [MIM: 300461, EC 2.1.3.3], a homotrimeric, intramitochondrial enzyme that catalyzes an early step in the urea cycle: condensation of carbamyl phosphate and ornithine to form citrulline 5 . The urea cycle is a dynamic homeostatic system necessary for the removal of waste nitrogen and de novo synthesis of arginine.…”

Section: Introductionmentioning

confidence: 99%

“…4 encodes OTC [MIM: 300461, EC 2.1.3.3], a homotrimeric, intramitochondrial enzyme that catalyzes an early step in the urea cycle: condensation of carbamyl phosphate and ornithine to form citrulline. 5 The urea cycle is a dynamic homeostatic system necessary for the removal of waste nitrogen and de novo synthesis of arginine. The physiological demands on waste nitrogen removal depend on the intake of dietary protein and the balance of anabolism and catabolism of endogenous protein.…”

mentioning

confidence: 99%

A promoter variant in theOTCgene associated with late and variable age of onset hyperammonemia

Han

Anderson

Björnsson

et al. 2022

J of Inher Metab Disea

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Ornithine transcarbamylase deficiency (OTCD) is an X‐linked inborn error caused by loss of function variants in the OTC gene typically associated with severe neonatal hyperammonemia. Rare examples of late‐onset OTCD have also been described. Here, we describe an OTC promoter variant, c.‐106C>A, in a conserved HNF4a binding site, identified in two male siblings in Family 1 whose first and only recognized episodes of severe hyperammonemia occurred at ages 14 and 39 years, respectively. We identified the same OTC variant segregating in a large family with late‐onset OTCD with variable expressivity (Family 2). We show that this OTC promoter variant reduces expression >5‐fold in a dual‐luciferase assay that tests promoter function. Addition of an upstream OTC enhancer increases expression of both the wild type and the c.‐106C>A variant promoter constructs >5‐fold with the mutant promoter still about fourfold lower than the wild type. Thus, in both contexts, the promoter variant results in substantially lower OTC expression. Under normal demand on urea cycle function, OTC expression in hemizygous males, although reduced, is sufficient to meet the demand for waste nitrogen excretion. However, in response to severe metabolic stress with attendant increased requirements on urea cycle function, the impaired promoter function results in inadequate OTC expression with resultant hyperammonemia. In the absence of precipitating events, hemizygotes with this allele are asymptomatic, explaining the late age of onset of hyperammonemia in affected individuals and the incomplete penetrance observed in some individuals in Family 2.

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Ornithine transcarbamylase from Neurospora crassa: Purification and properties

Cited by 12 publications

References 31 publications

Compartmental and regulatory mechanisms in the arginine pathways of Neurospora crassa and Saccharomyces cerevisiae.

Compartmental and regulatory mechanisms in the arginine pathways of Neurospora crassa and Saccharomyces cerevisiae.

Influences of temperature and threshold effect of NaCl concentration on Alpias vulpinus OCT

A promoter variant in theOTCgene associated with late and variable age of onset hyperammonemia

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