Abstract
Extracts of interferon-treated (mouse neoplastic fibroblast L929) cells synthesize unique 2'',5''-linked oligo(adenylic acid) 5''-phosphates in the presence of ATP and double-stranded RNA. 2'',5''-Linked oligo(adenylic acid) 5''-triphosphate inhibits protein synthesis at nanomolar concentrations by activating RNase. Oligo(adenylic acid) 5''-monophosphate and 5''-triphosphate are evidently potent inhibitors of vaccinia mRNA methylation in vitro. Both the methylation of the 5''-terminal guanine at the 7 position and the 2''-O-ribose methylation of the penultimate nucleoside are inhibited. Such inhibition of mRNA methylation is not due to degradation of the mRNA. Inhibition of the requisite modification of the 5'' terminus of mRNA by 2'',5''-linked oligo(adenylic acids) may be a mechanism of interferon action against DNA and RNA viruses in which mRNA derived from them are capped.