title: The structure and function of small nucleolar ribonucleoproteins.
abstract: Eukaryotes and archaea use two sets of specialized ribonucleoproteins (RNPs) to carry out sequence-specific methylation and pseudouridylation of RNA, the two most abundant types of modifications of cellular RNAs. In eukaryotes, these protein-RNA complexes localize to the nucleolus and are called small nucleolar RNPs (snoRNPs), while in archaea they are known as small RNPs (sRNP). The C/D class of sno(s)RNPs carries out ribose-2'-O-methylation, while the H/ACA class is responsible for pseudouridylation of their RNA targets. Here, we review the recent advances in the structure, assembly and function of the conserved C/D and H/ACA sno(s)RNPs. Structures of each of the core archaeal sRNP proteins have been determined and their assembly pathways delineated. Furthermore, the recent structure of an H/ACA complex has revealed the organization of a complete sRNP. Combined with current biochemical data, these structures offer insight into the highly homologous eukaryotic snoRNPs.
authors.affiliation: Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA.
authors.forename: Steve L
authors.initials: SL
authors.lastname: Reichow
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hamma
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Ferré-D'Amaré
authors.forename: Gabriele
authors.initials: G
authors.lastname: Varani
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000502:physiology; D006836:Hydro-Lyases / Q000737:chemistry / Q000502:physiology; D008780:Methyltransferases / Q000737:chemistry / Q000502:physiology; D008958:Models, Molecular; D020537:RNA, Small Nucleolar / Q000737:chemistry; D020718:Ribonucleoproteins, Small Nucleolar / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*
chemical_list: D019843:Archaeal Proteins; D002868:Chromosomal Proteins, Non-Histone; D020537:RNA, Small Nucleolar; D020718:Ribonucleoproteins, Small Nucleolar; C047458:fibrillarin; D008780:Methyltransferases; D006836:Hydro-Lyases; C022479:pseudouridylate synthetase