The occurrence of 2'-5' oligoadenylates in Escherichia coli

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Abstract
The use of a highly specific radioimmunoassay and of HPLC permitted us to confirm the occurrence of 2′–5′ oligoadenylates [px(A2′p5′)nA] in several strains of Escherichia coli. Cellular concentrations of 2′–5′ oligoadenylates ranged from 50 nM to 300 nM. The mixture of 2′–5′ oligoadenylates consisted primarily of pppA2′p5′A, pA2′p5′A, A2′p5′Ap and A2′p5′A under normal conditions of growth. None of them activated R Nase L. Infection of the bacteria with the single‐stranded DNA phage M13 or induction of a heat‐inducible, non‐lytic mutant of phage λ led to a significant increase in the total pool of 2′–5′ oligoadenylates, paralleling the progressive inhibition of growth. Likewise, the inhibition of protein synthesis with chloramphenicol stimulated the accumulation of 2′–5′ oligoadenylates. Furthermore, the inhibition of bacterial growth by either phage or by chloramphenicol brought about a change in the composition of the 2′–5′ oligoadenylate pool; 5′‐phosphorylated 2′–5′ oligoadenylates accumulated and became the major components. The findings indicate a parallelism between the effects of viral infection on the synthesis of 2′–5′ oligoadenylates in eukaryotes and similar effects subsequent to phage growth in the bacterium E. coli.

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