The 3'-terminal sequence of the small subunit ribosomal RNA from hamster mitochondria

The 220 3'-terminal nucleotides of the small ribosomal subunit RNA (13S) of hamster (BHK-21) cell mitochondria have been sequenced and the positions of post-transcriptionally methylated residues within this sequence have been established. Also, we have derived the secondary structure of the 3'-terminus of mitochondrial 13S rRNA by 1) searching nucleotide sequences of 13S rRNA, procaryotic 16S rRNA and eucaryotic 18S rRNA for common secondary structures and 2) using single-strand specific endonucleases to map secondary interactions in 13S rRNA. The pyrimidine tract CCUCC in E. coli 16S rRNA, which participates in base-pairing with bacterial mRNA, is absent in mitochondrial 13S rRNA. We believe that the binding of mRNA to mammalian mitochondrial ribosomes is not mediated by a conventional Shine-Dalgarno interaction.