Characterization of Labeled Residues from 5-Diazouracil-2-C Incorporated into Ribonucleic Acids of Filamentous Escherichia coli.

E. coli B, filamented with 5-diazouracil (DZU)-2-(14)C, yielded ribonucleic acid (RNA)-(DZU-2-(14)C) which was converted by pancreatic ribonuclease to (14)C-mono-and oligo-nucleotides. The mixed (14)C-mononucleotides isolated by diethylaminoethyl-cellulose fractionation were identified as cytidylic, uridylic, and hydroxyuridylic acids, by using a combination of paper chromatography and treatment with alkaline phosphatase and cytidine deaminase. Rifampin blocked incorporation of DZU-2-(14)C under conditions which inhibit RNA synthesis. Division inhibition by DZU-2-(14)C and the incorporation into Escherichia coli B were retarded by uracil but not by other RNA bases. In a pyrimidine-requiring E. coli, DZU substituted for uracil or cytosine to an extent limited by toxic effects. Cytosine and uracil retarded these effects and retarded the incorporation of DZU-2-(14)C into the pyrimidineless strain. A small proportion of DZU-2-(14)C was converted by the latter strain into hydroxyuridylic acid, but the bulk of the incorporated label was in cytidylic and uridylic acid, as in the wild strain.