Structural Studies of the Nucleolar Stages of Ribosome Biogenesis in Yeast
type: CreativeWork
description: The ribosome is the RNA-protein machine responsible for the essential task of translating mRNA into proteins. Ribosomes are heterodimers made up of a small subunit (SSU, 40S) and a large subunit (LSU, 60S). At the interface of these subunits, the mRNA is decoded by the small subunit and peptide bond formation is catalyzed by the rRNA of the large subunit. The cell therefore requires the timely and accurate assembly of functional ribosomal subunits, a complex process termed ribosome biogenesis. In addition to the ribosomal RNAs and ribosomal proteins that make up the mature subunits, eukaryotic cells require over 200 trans-acting factors to assemble ribosomes. This process begins in the nucleolus- a subcompartment of the nucleus- where the ribosomal DNA is transcribed to produce pre-ribosomal RNAs (pre-rRNAs). The newly transcribed pre-rRNAs recruit many assembly factors essential to their early folding, but many of these factors exact roles were largely unknown at the start of this work. Additionally, as the rRNA forms the active centers of the ribosome, the initial steps of rRNA folding and chaperoning are of great interest. Structural biology studies have elucidated snapshots of later stages of assembly, but structural understanding of the very early stages of ribosome assembly were limited at the start of this work, and therefore our understanding of early assembly factor function and rRNA folding was restricted. To gain insight into the earliest stages of large subunit assembly, we aimed to isolate and structurally characterize an early nucleolar stage of large subunit assembly. The structures of the nucleolar pre-60S provided insights into the roles of many nucleolus-specific assembly factors. Additionally, we observed that the pre-60S rRNA is largely disordered at this stage in assembly. The rRNA domains making up the solvent exposed side of the LSU are in a nearmature conformation, while the rRNA domains that will eventually form the active centers are largel…
abstract: The ribosome is the RNA-protein machine responsible for the essential task of translating mRNA into proteins. Ribosomes are heterodimers made up of a small subunit (SSU, 40S) and a large subunit (LSU, 60S). At the interface of these subunits, the mRNA is decoded by the small subunit and peptide bond formation is catalyzed by the rRNA of the large subunit. The cell therefore requires the timely and accurate assembly of functional ribosomal subunits, a complex process termed ribosome biogenesis. In addition to the ribosomal RNAs and ribosomal proteins that make up the mature subunits, eukaryotic cells require over 200 trans-acting factors to assemble ribosomes. This process begins in the nucleolus- a subcompartment of the nucleus- where the ribosomal DNA is transcribed to produce pre-ribosomal RNAs (pre-rRNAs). The newly transcribed pre-rRNAs recruit many assembly factors essential to their early folding, but many of these factors exact roles were largely unknown at the start of this work. Additionally, as the rRNA forms the active centers of the ribosome, the initial steps of rRNA folding and chaperoning are of great interest. Structural biology studies have elucidated snapshots of later stages of assembly, but structural understanding of the very early stages of ribosome assembly were limited at the start of this work, and therefore our understanding of early assembly factor function and rRNA folding was restricted. To gain insight into the earliest stages of large subunit assembly, we aimed to isolate and structurally characterize an early nucleolar stage of large subunit assembly. The structures of the nucleolar pre-60S provided insights into the roles of many nucleolus-specific assembly factors. Additionally, we observed that the pre-60S rRNA is largely disordered at this stage in assembly. The rRNA domains making up the solvent exposed side of the LSU are in a nearmature conformation, while the rRNA domains that will eventually form the active centers are largel…
author: Miller, Linamarie
keywords: ribosome biogenesis, rRNA folding, pre-60S, Dhr1 helicase, nucleolar assembly, structural biology, Life Sciences
date published: 2022-01-01T08:00:00Z
date modified: 2026-07-24T04:11:11Z
provider: Rockefeller
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Rockefeller