title: Assembly of Saccharomyces cerevisiae 60S ribosomal subunits: role of factors required for 27S pre-rRNA processing.
abstract: The precise functions of most of the ∼200 assembly factors and 79 ribosomal proteins required to construct yeast ribosomes in vivo remain largely unexplored. To better understand the roles of these proteins and the mechanisms driving ribosome biogenesis, we examined in detail one step in 60S ribosomal subunit assembly-processing of 27SA(3) pre-rRNA. Six of seven assembly factors required for this step (A(3) factors) are mutually interdependent for association with preribosomes. These A(3) factors are required to recruit Rrp17, one of three exonucleases required for this processing step. In the absence of A(3) factors, four ribosomal proteins adjacent to each other, rpL17, rpL26, rpL35, and rpL37, fail to assemble, and preribosomes are turned over by Rat1. We conclude that formation of a neighbourhood in preribosomes containing the A(3) factors establishes and maintains stability of functional preribosomes containing 27S pre-rRNAs. In the absence of these assembly factors, at least one exonuclease can switch from processing to turnover of pre-rRNA.
authors.affiliation: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA.
authors.forename: Aarti
authors.initials: A
authors.lastname: Sahasranaman
authors.forename: Jill
authors.initials: J
authors.lastname: Dembowski
authors.forename: John
authors.initials: J
authors.lastname: Strahler
authors.forename: Philip
authors.initials: P
authors.lastname: Andrews
authors.forename: Janine
authors.initials: J
authors.lastname: Maddock
authors.forename: John L
authors.initials: JL
authors.lastname: Woolford
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D005092:Exonucleases / Q000378:metabolism; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D009154:Mutation; D012322:RNA Precursors / Q000235:genetics*; D012335:RNA, Ribosomal / Q000235:genetics*; D012269:Ribosomal Proteins / Q000378:metabolism; D054683:Ribosome Subunits, Large, Eukaryotic / Q000235:genetics*; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D012322:RNA Precursors; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; C032493:ribosomal protein L17; C075577:RAT1 protein, S cerevisiae; D005092:Exonucleases; D005095:Exoribonucleases; C068398:XRN1 protein, S cerevisiae