A role for SUMOylation in snoRNP biogenesis revealed by quantitative proteomics

Nucleus. 2011 Jan-Feb;2(1):30-7. doi: 10.4161/nucl.2.1.14437.

Abstract

A role for SUMOylation in the biogenesis and/or function of Box C/D snoRNPs has been reported, mediated via SUMO2 conjugation to the core snoRNP protein, Nop58. A quantitative proteomics screen, based on SILAC (stable-isotope labeling by amino acids in cell culture) and mass spectrometry using extracts prepared from cultured mammalian cells expressing either 6His-SUMO1 or -SUMO2, revealed that the snoRNP-related proteins Nop58, Nhp2, DKC1 and NOLC1 are amongst the main SUMO-modified proteins in the nucleolus. SUMOylation of Nhp2 and endogenous Nop58 was confirmed using a combination of in vitro and cell-based assays and the modified lysines identified by site-directed mutagenesis. SUMOylation of Nop58 was found to be important for high-affinity Box C/D snoRNA binding and the localization of newly transcribed snoRNAs to the nucleolus. Here, these findings are reviewed and a model for understanding Nop58 SUMOylation in the context of Box C/D snoRNP biogenesis is presented. Given the essential role of snoRNPs in the modification of pre-ribosomal RNA, this work suggests that SUMO, snoRNPs and ribosome assembly, and thus cellular translation, growth and proliferation, may be linked via novel mechanisms which warrant further investigation.

Keywords: Nop5/Nop58; SILAC; SUMO; nucleolus; snoRNA; snoRNP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • HeLa Cells
  • Humans
  • Nuclear Proteins / metabolism
  • Proteomics*
  • RNA, Small Nucleolar / metabolism
  • Ribonucleoproteins, Small Nuclear / metabolism
  • Ribonucleoproteins, Small Nucleolar / metabolism*
  • Small Ubiquitin-Related Modifier Proteins / metabolism*

Substances

  • NHP2 protein, human
  • NOP58 protein, human
  • Nuclear Proteins
  • RNA, Small Nucleolar
  • Ribonucleoproteins, Small Nuclear
  • Ribonucleoproteins, Small Nucleolar
  • Small Ubiquitin-Related Modifier Proteins