Metabolism of pyrimidines and pyrimidine nucleosides by Salmonella typhimurium.

The pathways by which uracil, cytosine, uridine, cytidine, deoxyuridine, and deoxycytidine are metabolized by Salmonella typhimurium are established. The various 5-fluoropyrimidine analogues are shown to exert their toxic effects only after having been converted to the nucleotide level, and these conversions are shown to be catalyzed by the same enzymes which similarly convert the natural substrates. Methods for isolating mutant strains blocked in various steps of metabolism of pyrimidine bases and nucleosides are described.