A novel type of + 1 frameshift suppressor: a base substitution in the anticodon stem of a yeast mitochondrial serine-tRNA causes frameshift suppression.
We have identified a spontaneous mitochondrial mutation, mfs-1 (mitochondrial frameshift suppressor-1), which suppresses a + 1 frameshift mutation localized in the yeast mitochondrial oxi1 gene. The suppressor strain exhibits a single base change (C to U) at position 42 of the mitochondrial serine-tRNA (UCN). To our knowledge, this is the first reported case showing that a mutation in the anticodon stem of a tRNA can cause frameshift suppression. The expression and aminoacylation of the mutant tRNASer(UCN) are not significantly affected. However, the base change at position 42 has two effects: first, residue U27 of the mutant tRNA is not modified to pseudouridine as observed in wild-type tRNASer(UCN). Second, the base change and/or the lack of modification of U27 leads to an alteration in the secondary/tertiary structure of the mutant tRNA. It is possible that there are such structural changes in the anticodon loop that enable the tRNA to read a four base codon, UCCA, thus restoring the wild-type reading frame.
Hüttenhofer
A
A
Institut de Biologie Moléculaire et Cellulaire du CNRS, Laboratoire de Biochimie, Strasbourg, France.
Weiss-Brummer
B
B
Dirheimer
G
G
Martin
R P
RP
D000926:Anticodon / Q000235:genetics*; D001483:Base Sequence; D005800:Genes, Fungal; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D012313:RNA / Q000235:genetics* / Q000302:isolation & purification; D000077278:RNA, Mitochondrial; D012343:RNA, Transfer / Q000235:genetics*; D012345:RNA, Transfer, Amino Acid-Specific / Q000235:genetics*; D012362:RNA, Transfer, Ser / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D013489:Suppression, Genetic; D014158:Transcription, Genetic
D000926:Anticodon; D000077278:RNA, Mitochondrial; D012345:RNA, Transfer, Amino Acid-Specific; D012362:RNA, Transfer, Ser; D012313:RNA; D012343:RNA, Transfer