eLife (Mar 2020)

USP16 counteracts mono-ubiquitination of RPS27a and promotes maturation of the 40S ribosomal subunit

  • Christian Montellese,
  • Jasmin van den Heuvel,
  • Caroline Ashiono,
  • Kerstin Dörner,
  • André Melnik,
  • Stefanie Jonas,
  • Ivo Zemp,
  • Paola Picotti,
  • Ludovic C Gillet,
  • Ulrike Kutay

DOI
https://doi.org/10.7554/eLife.54435
Journal volume & issue
Vol. 9

Abstract

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Establishment of translational competence represents a decisive cytoplasmic step in the biogenesis of 40S ribosomal subunits. This involves final 18S rRNA processing and release of residual biogenesis factors, including the protein kinase RIOK1. To identify novel proteins promoting the final maturation of human 40S subunits, we characterized pre-ribosomal subunits trapped on RIOK1 by mass spectrometry, and identified the deubiquitinase USP16 among the captured factors. We demonstrate that USP16 constitutes a component of late cytoplasmic pre-40S subunits that promotes the removal of ubiquitin from an internal lysine of ribosomal protein RPS27a/eS31. USP16 deletion leads to late 40S subunit maturation defects, manifesting in incomplete processing of 18S rRNA and retarded recycling of late-acting ribosome biogenesis factors, revealing an unexpected contribution of USP16 to the ultimate step of 40S synthesis. Finally, ubiquitination of RPS27a appears to depend on active translation, pointing at a potential connection between 40S maturation and protein synthesis.

Keywords