Effect of oligonucleotide AGAGGAGGU on protein synthesis in vitro

The oligonucleotide AGAGGAGGU, complementary to the 3' end of 16S RNA has been shown to inhibit 70S initiation complex formation on E. coli ribosomes (Taniguchi, T. and Weissmann, C., 1978. Nature, 275, 770-772). We have prepared this nonanucleotide in larger quantities by a combination of DEAE cellulose-urea chromatography and reverse phase (RPC 5) chromatography. The inhibitory effect of AGAGGAGGU on initiation complex formation has been confirmed. Furthermore, when added to a complete system for in vitro protein synthesis, the translation of Q beta RNA was inhibited by the nonanucleotide. No selectivity was observed in the inhibition of the coat protein and replicase protein synthesis. When both Q beta RNA and pAUG were present, some stimulation of pAUG binding to 70S ribosomes was observed on addition of AGAGGAGGU, as previously reported (Taniguchi and Weissmann, ibid). No effect was observed in the absence of Q beta RNA. This observation is discussed.