title: The Shq1p.Naf1p complex is required for box H/ACA small nucleolar ribonucleoprotein particle biogenesis.
abstract: Small nucleolar ribonucleoprotein particles (snoRNPs) are essential cofactors in ribosomal RNA metabolism. Although snoRNP composition has been thoroughly characterized, the biogenesis process of these particles is poorly understood. We have identified two proteins from the yeast Saccharomyces cerevisiae, Yil104c/Shq1p and Ynl124w/Naf1p, which are essential and required for the stability of box H/ACA snoRNPs. Depletion of either Shq1p or Naf1p leads to a dramatic and specific decrease in box H/ACA snoRNA levels in vivo. A severe concomitant defect in ribosomal RNA processing is observed, consistent with the depletion of this family of snoRNAs. Shq1p and Naf1p show nuclear localization and interact with Nhp2p and Cbf5p, two core proteins of mature box H/ACA snoRNPs. Shq1p and Naf1p form a complex, but they are not strongly associated with box H/ACA snoRNPs. We propose that Shq1p and Naf1p are involved in the early biogenesis steps of box H/ACA snoRNP assembly.
authors.affiliation: Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095-1569, USA.
authors.forename: Pok Kwan
authors.initials: PK
authors.lastname: Yang
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rotondo
authors.forename: Tanya
authors.initials: T
authors.lastname: Porras
authors.forename: Pierre
authors.initials: P
authors.lastname: Legrain
authors.forename: Guillaume
authors.initials: G
authors.lastname: Chanfreau
mesh_terms: D004722:Endoribonucleases / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D046911:Macromolecular Substances; D009687:Nuclear Proteins / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012331:RNA, Fungal; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D043244:Ribonuclease III; D017411:Ribonucleoproteins, Small Nuclear / Q000096:biosynthesis*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D005656:Fungal Proteins; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D012331:RNA, Fungal; D012335:RNA, Ribosomal; D017411:Ribonucleoproteins, Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; C470008:Shq1 protein, S cerevisiae; D004722:Endoribonucleases; C468367:RNT1 protein, S cerevisiae; D043244:Ribonuclease III