Rrp6p, the yeast homologue of the human PM-Scl 100-kDa autoantigen, is essential for efficient 5.8 S rRNA 3' end formation.
The eukaryotic 25 S, 18 S, and 5.8 S rRNAs are synthesized as a single transcript with two internal transcribed spacers (ITS1 and ITS2), which are removed by endo- and exoribonucleolytic steps to produce mature rRNA. Genetic selection for suppressors of a polyadenylation defect yielded two cold-sensitive alleles of a gene that we named RRP6 (ribosomal RNA processing). Molecular cloning of RRP6 revealed its homology to a 100-kDa human, nucleolar PM-Scl autoantigen and to Escherichia coli RNase D, a 3'-5' exoribonuclease. Recessive mutations in rrp6 result in the accumulation of a novel 5. 8 S rRNA processing intermediate, called 5.8 S*, which has normal 5' ends, but retains approximately 30 nucleotides of ITS2. Pulse-chase analysis of 5.8 S rRNA processing in an rrp6- strain revealed a precursor-product relationship between 5.8 S* and 5.8 S rRNAs, suggesting that Rrp6p plays a role in the removal of the last 30 nucleotides of ITS2 from 5.8 S precursors. A portion of 5.8 S* rRNA assembles into 60 S ribosomes which form polyribosomes, suggesting that they function in protein synthesis. These findings indicate that Rrp6p plays a role in 5.8 S rRNA 3' end formation, and they identify a functional intermediate in the rRNA processing pathway.
Briggs
M W
MW
Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14618, USA.
Burkard
K T
KT
Butler
J S
JS
D000595:Amino Acid Sequence; D001324:Autoantigens / Q000378:metabolism*; D003001:Cloning, Molecular; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016153:Genes, Suppressor; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames; D012323:RNA Processing, Post-Transcriptional; D012340:RNA, Ribosomal, 5.8S / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D001324:Autoantigens; D005656:Fungal Proteins; D012340:RNA, Ribosomal, 5.8S; D029701:Saccharomyces cerevisiae Proteins; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex; C077044:EXOSC10 protein, human; C112610:RRP6 protein, S cerevisiae