Substitution of an invariant nucleotide at the base of the highly conserved ‘530–loop’ of 15S rRNA causes suppression of yeast mitochondrial ochre mutations

Abstract

We have determined the nucleotide sequence alteration in the 15S rRNA gene of a Saccharomyces cerevisae strain carrying the previously described mitochondrial ochre suppressor, MSU1. The suppressor contains an A residue at position 633 of the yeast mitochondrial sequence, in place of the wild-type G. This position, located in the higly conserved region forming the stem of the ''530-loop'', corresponds to G517 of the Escherichia coli 16S rRNA and is occupied by G in all other known small rRNA sequences. This finding strongly supports the previous conclusions of others that the 530-loop region plays an important role in enhancing translational accuracy.