title: Box C/D snoRNP catalysed methylation is aided by additional pre-rRNA base-pairing.
abstract: 2'-O-methylation of eukaryotic ribosomal RNA (r)RNA, essential for ribosome function, is catalysed by box C/D small nucleolar (sno)RNPs. The RNA components of these complexes (snoRNAs) contain one or two guide sequences, which, through base-pairing, select the rRNA modification site. Adjacent to the guide sequences are protein-binding sites (the C/D or C'/D' motifs). Analysis of >2000 yeast box C/D snoRNAs identified additional conserved sequences in many snoRNAs that are complementary to regions adjacent to the rRNA methylation site. This 'extra base-pairing' was also found in many human box C/D snoRNAs and can stimulate methylation by up to five-fold. Sequence analysis, combined with RNA-protein crosslinking in Saccharomyces cerevisiae, identified highly divergent box C'/D' motifs that are bound by snoRNP proteins. In vivo rRNA methylation assays showed these to be active. Our data suggest roles for non-catalytic subunits (Nop56 and Nop58) in rRNA binding and support an asymmetric model for box C/D snoRNP organization. The study provides novel insights into the extent of the snoRNA-rRNA interactions required for efficient methylation and the structural organization of the snoRNPs.
authors.affiliation: Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Robert Willem
authors.initials: RW
authors.lastname: van Nues
authors.forename: Sander
authors.initials: S
authors.lastname: Granneman
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Kudla
authors.forename: Katherine Elizabeth
authors.initials: KE
authors.lastname: Sloan
authors.forename: Matthew
authors.initials: M
authors.lastname: Chicken
authors.forename: David
authors.initials: D
authors.lastname: Tollervey
authors.forename: Nicholas James
authors.initials: NJ
authors.lastname: Watkins
mesh_terms: D020029:Base Pairing / Q000235:genetics*; D001483:Base Sequence; D002384:Catalysis; D017124:Conserved Sequence / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism*; D020718:Ribonucleoproteins, Small Nucleolar / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*
chemical_list: D012322:RNA Precursors; D012331:RNA, Fungal; D020718:Ribonucleoproteins, Small Nucleolar