title: Rrp8p is a yeast nucleolar protein functionally linked to Gar1p and involved in pre-rRNA cleavage at site A2.
abstract: Chemical modifications and processing of the 18S, 5.8S, and 25S ribosomal RNAs from the 35S pre-ribosomal RNA depend on an important set of small nucleolar ribonucleoprotein particles (snoRNPs). Genetic depletion of yeast Gar1p, an essential common component of H/ACA snoRNPs, leads to inhibition of uridine isomerizations to pseudo-uridines on the 35S pre-rRNA and of the early pre-rRNA cleavages at sites A1 and A2, resulting in a loss of mature 18S rRNA synthesis. To identify Gar1p functional partners, we screened for mutations that are synthetically lethal with a gar1 mutant allele encoding a Gar1p mutant protein lacking its two glycine/arginine-rich (GAR) domains. We identified a previously uncharacterized Saccharomyces cerevisiae open reading frame, YDR083W (now designated RRP8), that encodes a highly conserved protein containing motifs found in methyltransferases. Rrp8p localizes to the nucleolus. A yeast strain lacking this protein is viable at 30 degrees C but displays strong growth impairment at lower temperatures. In this strain, cleavage of the pre-rRNA at site A2 is strongly affected whereas cleavages at sites A0 and A1 are only slightly inhibited or delayed.
authors.affiliation: Laboratoire de Biologie Moléculaire Eucaryote du Centre National de la Recherche Scientifique, Toulouse, France.
authors.forename: C
authors.initials: C
authors.lastname: Bousquet-Antonelli
authors.forename: E
authors.initials: E
authors.lastname: Vanrobays
authors.forename: J P
authors.initials: JP
authors.lastname: Gélugne
authors.forename: M
authors.initials: M
authors.lastname: Caizergues-Ferrer
authors.forename: Y
authors.initials: Y
authors.lastname: Henry
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D008040:Genetic Linkage; D006868:Hydrolysis; D008780:Methyltransferases / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics; D011497:Protein O-Methyltransferase; D012322:RNA Precursors / Q000737:chemistry* / Q000235:genetics; D020537:RNA, Small Nucleolar / Q000737:chemistry* / Q000235:genetics; D020718:Ribonucleoproteins, Small Nucleolar; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014461:Ultracentrifugation
chemical_list: D005656:Fungal Proteins; D009687:Nuclear Proteins; D012322:RNA Precursors; D020537:RNA, Small Nucleolar; D020718:Ribonucleoproteins, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; C073180:GAR1 protein, S cerevisiae; D008780:Methyltransferases; D011497:Protein O-Methyltransferase; C410601:RRP8 protein, S cerevisiae