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.
Department of Microbiology, University of Florida, Gainesville, Florida 32601.
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