High-resolution proton magnetic resonance study of the secondary structure of the 3'-terminal 49-nucleotide fragment of 16S rRNA from Escherichia coli.

Abstract
The 3'' terminus of 16S rRNA is implicated in the recognition of mRNA by the ribosome. A fragment containing the 3''-terminal 49 nucleotides cleaved from the rRNA by cloacin DF13 was isolated in a pure form. The secondary structure of this fragment was studied by measuring the high-resolution PMR spectra. The resonances observed at low field can be assigned to H-bonded iminoprotons of base-pairs present in the fragment. The rRNA fragment, under the conditions used, apparently exists as a hairpin consisting of 8 intramolecular base-pairs, the 3''-terminal dodecanucleotide being unpaired. The implications of these findings are discussed in terms of the function of the ribosomal protein S1.