Sequential domain assembly of ribosomal protein S3 drives 40S subunit maturation

Nat Commun. 2016 Feb 2;7:10336. doi: 10.1038/ncomms10336.

Abstract

Eukaryotic ribosomes assemble by association of ribosomal RNA with ribosomal proteins into nuclear precursor particles, which undergo a complex maturation pathway coordinated by non-ribosomal assembly factors. Here, we provide functional insights into how successive structural re-arrangements in ribosomal protein S3 promote maturation of the 40S ribosomal subunit. We show that S3 dimerizes and is imported into the nucleus with its N-domain in a rotated conformation and associated with the chaperone Yar1. Initial assembly of S3 with 40S precursors occurs via its C-domain, while the N-domain protrudes from the 40S surface. Yar1 is replaced by the assembly factor Ltv1, thereby fixing the S3 N-domain in the rotated orientation and preventing its 40S association. Finally, Ltv1 release, triggered by phosphorylation, and flipping of the S3 N-domain into its final position results in the stable integration of S3. Such a stepwise assembly may represent a new paradigm for the incorporation of ribosomal proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Gene Expression Regulation / physiology*
  • Gene Expression Regulation, Fungal / physiology
  • Models, Molecular
  • Phosphorylation
  • Protein Conformation
  • Protein Subunits
  • Protein Transport
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*

Substances

  • Fungal Proteins
  • LTV1 protein, S cerevisiae
  • Protein Subunits
  • RPS3 protein, S cerevisiae
  • Ribosomal Proteins
  • Saccharomyces cerevisiae Proteins
  • YAR1 protein, S cerevisiae