Proteomic analyses identify a diverse array of nuclear processes affected by small ubiquitin-like modifier conjugation in Arabidopsis

Marcus J. Miller, Gregory A. Barrett-Wilt, Zhihua Hua, Richard D. Vierstra

Research output: Contribution to journalArticlepeer-review

240 Scopus citations

Abstract

The covalent attachment of SUMO (small ubiquitin-like modifier) to other intracellular proteins affects a broad range of nuclear processes in yeast and animals, including chromatin maintenance, transcription, and transport across the nuclear envelope, as well as protects proteins from ubiquitin addition. Substantial increases in SUMOylated proteins upon various stresses have also implicated this modification in the general stress response. To help understand the role(s) of SUMOylation in plants, we developed a stringent method to isolate SUMO-protein conjugates from Arabidopsis thaliana that exploits a tagged SUMO1 variant that faithfully replaces the wild-type protein. Following purification under denaturing conditions, SUMOylated proteins were identified by tandem mass spectrometry from both nonstressed plants and those exposed to heat and oxidative stress. The list of targets is enriched for factors that direct SUMOylation and for nuclear proteins involved in chromatin remodeling/repair, transcription, RNA metabolism, and protein trafficking. Targets of particular interest include histone H2B, components in the LEUNIG/TOPLESS corepressor complexes, and proteins that control histone acetylation and DNA methylation, which affect genome-wide transcription. SUMO attachment site(s) were identified in a subset of targets, including SUMO1 itself to confirm the assembly of poly-SUMO chains. SUMO1 also becomes conjugated with ubiquitin during heat stress, thus connecting these two posttranslational modifications in plants. Taken together, we propose that SUMOylation represents a rapid and global mechanism for reversibly manipulating plant chromosomal functions, especially during environmental stress.

Original languageEnglish
Pages (from-to)16512-16517
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number38
DOIs
StatePublished - Sep 21 2010

Keywords

  • Chromatin remodeling
  • Mass spectrometry
  • SUMO
  • Stress
  • TOPLESS

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