engleski

In vivo regulation of pyrimidine catabolism in Escherichia coli

Although pyrimidine metabolism in E.coli has been intensively investigated, the data on the catabolism of thymine and uracil and its regulation are still lacking. We report the evidence for breakdown of thymine and uracil to CO2, NH3 and urea via respective barbituric acids. In bacteria grown in media optimally supplied with carbon and nitrogen source or in media in which pyrimidines were used as sole carbon source, the activity of degradative enzymes could not be detected. The induction of catabolic enzymes took place in glucose-media supplemented with suboptimal concentrations of NH4+ salts or with different amino acids as source of nitrogen. Since the initiation and the rate of breakdown depended on amino acid used as nitrogen source, it is reasonable to assume that the induction of catabolic enzymes is somehow regulated by the amount of nitrogen metabolically available in the cell.

Escherichia coli; pyrimidine catabolism

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