A Proteomic Screen for Nucleolar SUMO Targets Shows SUMOylation Modulates the Function of Nop5/Nop58

Belinda J. Westman, Céline Verheggen, Saskia Hutten, Yun Wah Lam, Edouard Bertrand, Angus I. Lamond

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

Posttranslational SUMO modification is an important mechanism of regulating protein function, especially in the cell nucleus. The nucleolus is the subnuclear organelle responsible for rRNA synthesis, processing, and assembly of the large and small ribosome subunits. Here, we have used SILAC-based quantitative proteomics to identify nucleolar SUMOylated proteins. This reveals a role for SUMOylation in the biogenesis and/or function of small nucleolar ribonucleoprotein complexes (snoRNPs) via the targeting of Nhp2 and Nop58. Using combined in vitro and in vivo approaches, both Nhp2 and Nop58 (also known as Nop5) are shown to be substrates for SUMOylation. Mutational analyses revealed the sites of modification on Nhp2 as K5, and on Nop58 as K467 and K497. Unlike Nop58 and Nhp2, the closely related Nop56 and 15.5K proteins appear not to be SUMO targets. SUMOylation is essential for high-affinity Nop58 binding to snoRNAs. This study provides direct evidence linking SUMO modification with snoRNP function.

Original languageEnglish
Pages (from-to)618-631
Number of pages14
JournalMolecular Cell
Volume39
Issue number4
Early online date26 Aug 2010
DOIs
Publication statusPublished - 27 Aug 2010
Externally publishedYes

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