title: The family of box ACA small nucleolar RNAs is defined by an evolutionarily conserved secondary structure and ubiquitous sequence elements essential for RNA accumulation.
abstract: Eukaryotic cells contain a large number of small nucleolar RNAs (snoRNAs). A major family of snoRNAs features a consensus ACA motif positioned 3 nucleotides from the 3' end of the RNA. In this study we have characterized nine novel human ACA snoRNAs (U64-U72). Structural probing of U64 RNA followed by systematic computer modeling of all known box ACA snoRNAs revealed that this class of snoRNAs is defined by a phylogenetically conserved secondary structure. The ACA snoRNAs fold into two hairpin structures connected by a single-stranded hinge region and followed by a short 3' tail. The hinge region carries an evolutionarily conserved sequence motif, called box H (consensus, AnAnnA). The H box, probably in concert with the flanking helix structures and the ACA box characterized previously, plays an essential role in the accumulation of human U64 intronic snoRNA. The correct processing of a yeast ACA snoRNA, snR36, in mammalian cells demonstrated that the cis- and trans-acting elements required for processing and accumulation of ACA snoRNAs are evolutionarily conserved. The notion that ACA snoRNAs share a common secondary structure and conserved box elements that likely function as binding sites for common proteins (e.g., GAR1) suggests that these RNAs possess closely related nucleolar functions.
authors.affiliation: Laboratoire de Biologie Moléculaire Eucaryote du Centre National de laRecherche (CNRS), Université Paul Sabatier, Toulouse, France.
authors.forename: P
authors.initials: P
authors.lastname: Ganot
authors.forename: M
authors.initials: M
authors.lastname: Caizergues-Ferrer
authors.forename: T
authors.initials: T
authors.lastname: Kiss
mesh_terms: D001483:Base Sequence; D005075:Biological Evolution; D002466:Cell Nucleolus / Q000235:genetics*; D002868:Chromosomal Proteins, Non-Histone / Q000032:analysis; D003198:Computer Simulation; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000032:analysis; D006367:HeLa Cells; D006801:Humans; D007438:Introns / Q000235:genetics; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D005810:Multigene Family; D009687:Nuclear Proteins / Q000032:analysis; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D012323:RNA Processing, Post-Transcriptional; D012342:RNA, Small Nuclear / Q000096:biosynthesis / Q000145:classification / Q000235:genetics*; D020718:Ribonucleoproteins, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; D013045:Species Specificity
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D005656:Fungal Proteins; D009687:Nuclear Proteins; D012342:RNA, Small Nuclear; D020718:Ribonucleoproteins, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; C047458:fibrillarin; C073180:GAR1 protein, S cerevisiae