Degradation of pyrimidines in Euglena gracills III. Ratio of uracil to thymine degradation

Wasternack, Claus; Krauss, Gerhard; Reinbothe, H.

doi:10.1016/0304-4211(77)90119-5

Cited by 15 publications

(9 citation statements)

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“…5A). This is consistent with the fact that uracil and thymine are degraded by the same enzymes in E. gracilis (27,28). The pool increase was a reversible, time-dependent, and saturable process (Fig.…”

Section: Resultssupporting

confidence: 88%

“…As in many other organisms, uracil in E. gracilis is either metabolized by salvage reactions and incorporated into nucleotides and nucleic acids (27), or it is degraded reductively (24). The ratio between the anabolic and the catabolic pathways is approximately 3:1 (27).…”

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confidence: 98%

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confidence: 99%

“…The ratio between the anabolic and the catabolic pathways is approximately 3:1 (27). The ratio can be shifted by a high dosage of degradative intermediates (dihydropyrimidines) toward increased salvage (27). Degradation of both uracil and thymine takes place reductively in a three-step sequence catalyzed by the same enzymes, uracil reductase, dihydropyrimidinase, and 3-ureidopropionase (28) (Fig.…”

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confidence: 99%

“…Measurement of uptake and incorporation was as described previously (25). The radioactivity in the perchloric acid-insoluble fraction represents a measure of RNA labeling (27).…”

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confidence: 99%

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Compartmentation of uracil in Euglena gracilis.

Wasternack¹

1983

Mol. Cell. Biol.

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Compartmentation of uracil in the flagellate Euglena gracilis was studied by tracer-kinetic experiments. Lag times in the equilibration of exogenously given and intracellularly present uracil before linear labeling of catabolic and anabolic products was determined to estimate the size of its metabolically active pool. This pool operates in the incorporation and degradation of uracil. There were the same lag times in forming both final products when measured in parallel and when measured after preloading with pyrimidines, in different cell strains, and under various environmental conditions. The amount of the metabolically active uracil pool, estimated as 11 pmol/10(7) heterotrophically growing cells, decreased to almost zero during light-induced RNA synthesis and could be changed by preloading with uracil or thymine. Besides this metabolic pool, cells may contain large amounts of uracil in a membrane-enclosed storage compartment (up to 12 nmol/10(7) cells). This is metabolically inert, but may be mobilized by nitrogen-carbon starvation. The role of uracil compartmentation in this metabolically flexible organism is discussed.

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Section: Resultssupporting

confidence: 88%

mentioning

confidence: 98%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…Measurement of uptake and incorporation was as described previously (25). The radioactivity in the perchloric acid-insoluble fraction represents a measure of RNA labeling (27).…”

mentioning

confidence: 99%

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