title: The assembly factor Erb1 functions in multiple remodeling events during 60S ribosomal subunit assembly in S. cerevisiae.
abstract: A major gap in our understanding of ribosome assembly is knowing the precise function of each of the ∼200 assembly factors. The steps in subunit assembly in which these factors participate have been examined for the most part by depleting each protein from cells. Depletion of the assembly factor Erb1 prevents stable assembly of seven other interdependent assembly factors with pre-60S subunits, resulting in turnover of early preribosomes, before the ITS1 spacer can be removed from 27SA3 pre-rRNA. To investigate more specific functions of Erb1, we constructed eight internal deletions of 40-60 amino acid residues each, spanning the amino-terminal half of Erb1. The erb1Δ161-200 and erb1Δ201-245 deletion mutations block a later step than depletion of Erb1, namely cleavage of the C2 site that initiates removal of the ITS2 spacer. Two other remodeling events fail to occur in these erb1 mutants: association of twelve different assembly factors with domain V of 25S rRNA, including the neighborhood surrounding the peptidyl transferase center, and stable association of ribosomal proteins with rRNA surrounding the polypeptide exit tunnel. This suggests that successful initiation of construction of these functional centers is a checkpoint for committing to spacer removal.
authors.affiliation: Department of Biological Sciences, Carnegie Mellon University, 616 Mellon Institute, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
authors.forename: Salini
authors.initials: S
authors.lastname: Konikkat
authors.affiliation: Department of Biological Sciences, Carnegie Mellon University, 616 Mellon Institute, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Biedka
authors.affiliation: Department of Biological Sciences, Carnegie Mellon University, 616 Mellon Institute, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Woolford
mesh_terms: D002467:Cell Nucleus / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D012322:RNA Precursors / Q000235:genetics*; D012269:Ribosomal Proteins / Q000235:genetics*; D054683:Ribosome Subunits, Large, Eukaryotic / Q000235:genetics; D012270:Ribosomes / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*
chemical_list: D021903:DNA, Ribosomal Spacer; C506467:Erb1 protein, S cerevisiae; D012322:RNA Precursors; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins