5 S rRNA is involved in fidelity of translational reading frame.
Chromosomal mutants (maintenance of frame = mof) in which the efficiency of -1 ribosomal frameshifting is increased can be isolated using constructs in which lacZ expression is dependent upon a -1 shift of reading frame. We isolate a new mof mutation, mof9, in Saccharomyces cerevisiae and show that it is complemented by both single and multi-copy 5 S rDNA clones. Two independent insertion mutations in the rDNA locus (rDNA::LEU2 and rDNA::URA3) also display the Mof- phenotype and are also complemented by single and multi-copy 5 S rDNA clones. Mutant 5 S rRNAs expressed from a plasmid as 20-50% of total 5 S rRNA in a wild-type host also induced the Mof- phenotype. The increase in frameshifting is greatest when the lacZ reporter gene is expressed on a high copy, episomal vector. No differences were found in 5 S rRNA copy number or electrophoretic mobilities in mof9 strains. Both mof9 and rDNA::LEU2 increase the efficiency of +1 frameshifting as well but have no effect on readthrough of UAG or UAA termination codons, indicating that not all translational specificity is affected. These data suggest a role for 5 S rRNA in the maintenance of frame in translation.
Dinman
J D
JD
Section on Genetics of Simple Eukaryotes, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Wickner
R B
RB
D001483:Base Sequence; D003001:Cloning, Molecular; D004271:DNA, Fungal; D016368:Frameshift Mutation; D018965:Frameshifting, Ribosomal; D005800:Genes, Fungal; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D010641:Phenotype; D012341:RNA, Ribosomal, 5S / Q000235:genetics*; D016364:Reading Frames; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*
D004271:DNA, Fungal; D012341:RNA, Ribosomal, 5S