Mechanism of ribosomal subunit association: oligodeoxynucleotides as probes

From the kethoxal treatment data [Herr, W.; Chapman, N.M.; Noller, H.F. (1979) J. Mol. Biol. 130, 433-439] some regions of ribosomal RNAs are thought to be responsible for the association of 30S and 50S ribosomes of E. coli to form 70S ribosomes. In order to test this possibility about a dozen oligodeoxynucleotides complementary to the suspected regions of rRNAs were synthesised. Their association with ribosomes and naked rRNAs was tested by the gel filtration technique. In order to check the effects on the ribosomal subunit association or rRNA association either intact 30S and 50S ribosomes or naked 16S and 23S rRNAs were preincubated with the individual oligodeoxynucleotide and its effect was checked by density gradient centrifugation followed by UV absorbance monitoring. Some oligodeoxynucleotides interfered with either subunit association or 16S RNA and 23S RNA association, some with both. These data clearly indicate that RNA-RNA interaction plays the major role in ribosomal subunit association.