title: A translational fidelity mutation in the universally conserved sarcin/ricin domain of 25S yeast ribosomal RNA.
abstract: Recent evidence suggests that ribosomal RNAs have functional roles in translation. We describe here a new ribosomal RNA mutation that causes translational suppression and antibiotic resistance in eukaryotic cells. Using random mutagenesis of the cloned ribosomal RNA gene and in vivo selection, we isolated a C --> U mutation in the universally conserved sarcin/ricin domain in Saccharomyces cerevisiae 25S ribosomal RNA. This mutation changes the putative CG pair, which closes the GAGA tetraloop in the sarcin/ricin domain, into a weaker UG pair without eliminating ribosomal sensitivity to ricin. We show that suppression of several UGA, UAG, and frameshift mutations is evident when a portion of the cellular ribosomal RNA contains the C --> U mutation. Cells that contain essentially all mutant ribosomal RNA grow only 10% slower than the wild-type, but show increased suppression as well as resistance to paramomycin, G418, and hygromycin, and sensitivity to cycloheximide. Our results provide genetic evidence for the participation of the sarcin/ricin loop in maintaining translational accuracy and are discussed in terms of a hypothesis that this ribosomal RNA region normally undergoes a conformational change during translation.
authors.affiliation: Laboratory for Molecular Biology (M/C 567), University of Illinois at Chicago 60607-7174, USA.
authors.forename: R
authors.initials: R
authors.lastname: Liu
authors.forename: S W
authors.initials: SW
authors.lastname: Liebman
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D017124:Conserved Sequence / Q000235:genetics*; D003513:Cycloheximide / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004722:Endoribonucleases; D005656:Fungal Proteins; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017354:Point Mutation / Q000235:genetics*; D014176:Protein Biosynthesis / Q000235:genetics*; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D012276:Ricin / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D013489:Suppression, Genetic
chemical_list: D000900:Anti-Bacterial Agents; D005656:Fungal Proteins; D012335:RNA, Ribosomal; C065039:RNA, ribosomal, 25S; C014801:alpha-sarcin; D012276:Ricin; D003513:Cycloheximide; D004722:Endoribonucleases