title: Modification of U6 spliceosomal RNA is guided by other small RNAs.
abstract: The vertebrate spliceosomal snRNAs are highly modified by pseudouridylation and 2'-O-methylation. We have identified novel conserved small RNAs that can direct addition of two methyl groups in U6 snRNA, at A47 and C77. These guide RNAs, mgU6-47 (methylation guide for U6 snRNA residue 47) and mgU6-77 contain boxes C, C', D, and D' and associate with fibrillarin. Each RNA can form a duplex with U6 snRNA positioning A47 and C77 for 2'-O-methylation. The antisense element of mgU6-77 can also position C2970 of 28S rRNA for 2'-O-methylation. Depletion of mgU6-77 from Xenopus oocytes prevents 2'-O-methylation of both C77 in U6 and C2970 in 28S; methylation can be restored by injecting in vitro transcribed mgU6-77. Thus, mgU6-77 appears to function in the 2'-O-methylation of two distinct classes of cellular RNA, snRNA, and rRNA.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536, USA.
authors.forename: K T
authors.initials: KT
authors.lastname: Tycowski
authors.forename: Z H
authors.initials: ZH
authors.lastname: You
authors.forename: P J
authors.initials: PJ
authors.lastname: Graham
authors.forename: J A
authors.initials: JA
authors.lastname: Steitz
mesh_terms: D000818:Animals; D001483:Base Sequence; D002458:Cell Fractionation; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000276:immunology / Q000378:metabolism; D019281:Dimerization; D006367:HeLa Cells; D006801:Humans; D008745:Methylation / Q000187:drug effects; D051379:Mice; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D009865:Oocytes; D011233:Precipitin Tests; D012339:RNA, Ribosomal, 28S / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D016914:Ribonuclease H / Q000378:metabolism; D017381:Spliceosomes / Q000737:chemistry / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D020319:Oligodeoxyribonucleotides, Antisense; D012339:RNA, Ribosomal, 28S; D012342:RNA, Small Nuclear; C047458:fibrillarin; D016914:Ribonuclease H