title: 90S pre-ribosomes include the 35S pre-rRNA, the U3 snoRNP, and 40S subunit processing factors but predominantly lack 60S synthesis factors.
abstract: We report the characterization of early pre-ribosomal particles. Twelve TAP-tagged components each showed nucleolar localization, sedimented at approximately 90S on sucrose gradients, and coprecipitated both the 35S pre-rRNA and the U3 snoRNA. Thirty-five non-ribosomal proteins were coprecipitated, including proteins associated with U3 (Nop56p, Nop58p, Sof1p, Rrp9, Dhr1p, Imp3p, Imp4p, and Mpp10p) and other factors required for 18S rRNA synthesis (Nop14p, Bms1p, and Krr1p). Mutations in components of the 90S pre-ribosomes impaired 40S subunit assembly and export. Strikingly, few components of recently characterized pre-60S ribosomes were identified in the 90S pre-ribosomes. We conclude that the 40S synthesis machinery predominately associates with the 35S pre-rRNA factors, whereas factors required for 60S subunit synthesis largely bind later, showing an unexpected dichotomy in binding.
authors.affiliation: Cellzome AG, Meyerhofstrasse 1, 69117, Heidelberg, Germany
authors.forename: Paola
authors.initials: P
authors.lastname: Grandi
authors.forename: Vladimir
authors.initials: V
authors.lastname: Rybin
authors.forename: Jochen
authors.initials: J
authors.lastname: Bassler
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Petfalski
authors.forename: Daniela
authors.initials: D
authors.lastname: Strauss
authors.forename: Martina
authors.initials: M
authors.lastname: Marzioch
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schäfer
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kuster
authors.forename: Herbert
authors.initials: H
authors.lastname: Tschochner
authors.forename: David
authors.initials: D
authors.lastname: Tollervey
authors.forename: Anne Claude
authors.initials: AC
authors.lastname: Gavin
authors.forename: Ed
authors.initials: E
authors.lastname: Hurt
mesh_terms: D015152:Blotting, Northern; D015153:Blotting, Western; D002499:Centrifugation, Density Gradient; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D046911:Macromolecular Substances; D008970:Molecular Weight; D021122:Protein Subunits; D012322:RNA Precursors / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism*; D020718:Ribonucleoproteins, Small Nucleolar / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015003:Yeasts / Q000166:cytology* / Q000235:genetics*
chemical_list: D005656:Fungal Proteins; D046911:Macromolecular Substances; D021122:Protein Subunits; D012322:RNA Precursors; D012335:RNA, Ribosomal; D020718:Ribonucleoproteins, Small Nucleolar; C117377:ribonucleoprotein, U3 small nucleolar