title: A dimeric structure for archaeal box C/D small ribonucleoproteins.
abstract: Methylation of ribosomal RNA (rRNA) is required for optimal protein synthesis. Multiple 2'-O-ribose methylations are carried out by box C/D guide ribonucleoproteins [small ribonucleoproteins (sRNPs) and small nucleolar ribonucleoproteins (snoRNPs)], which are conserved from archaea to eukaryotes. Methylation is dictated by base pairing between the specific guide RNA component of the sRNP or snoRNP and the target rRNA. We determined the structure of a reconstituted and catalytically active box C/D sRNP from the archaeon Methanocaldococcus jannaschii by single-particle electron microscopy. We found that archaeal box C/D sRNPs unexpectedly formed a dimeric structure with an alternative organization of their RNA and protein components that challenges the conventional view of their architecture. Mutational analysis demonstrated that this di-sRNP structure was relevant for the enzymatic function of archaeal box C/D sRNPs.
authors.affiliation: Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Franziska
authors.initials: F
authors.lastname: Bleichert
authors.forename: Keith T
authors.initials: KT
authors.lastname: Gagnon
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Brown
authors.forename: E Stuart
authors.initials: ES
authors.lastname: Maxwell
authors.forename: Andres E
authors.initials: AE
authors.lastname: Leschziner
authors.forename: Vinzenz M
authors.initials: VM
authors.lastname: Unger
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Baserga
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D001483:Base Sequence; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry*; D017015:Methanococcales / Q000737:chemistry*; D008854:Microscopy, Electron; D008958:Models, Molecular; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D019642:RNA, Archaeal / Q000737:chemistry* / Q000648:ultrastructure; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D019843:Archaeal Proteins; D002868:Chromosomal Proteins, Non-Histone; D019642:RNA, Archaeal; D012261:Ribonucleoproteins; C047458:fibrillarin