Mechanism of Inhibition of Bacterial Growth by Adenine

1) The growth of Escherichia coli K12 W3110 was inhibited by the addition of adenine to the medium. The syntheses of DNA, RNA, and protein also were co-ordinately inhibited by adenine. 2) The growth inhibition caused by adenine was overcome by uridine, but was enhanced in the presence of adenosine, inosine, or guanosine. 3) In the presence of adenine, the pool size of ATP increased two-fold while those of CTP and UTP were markedly reduced. The pyrimidine nucleotide pools were restored to normal levels when uridine was added together with adenine. 4) The incorporation of uracil or orotic acid into nucleic acid was inhibited by adenine, while that of uridine was not inhibited. 5) These results suggest that the growth inhibition provoked by adenine is attributable to inhibition of the de novo synthesis of pyrimidine nucleotides, probably at the step from orotic acid to UMP.