Decoding the SUMO Proteome: A Mass Spectrometry Workflow for Site-Specific Identification

Protein SUMOylation is a dynamic post-translational modification that regulates numerous cellular processes, including DNA repair, transcription, and proteostasis. SUMO modifiers are conjugated to lysine residues on substrate proteins via a conserved enzymatic cascade and can form diverse chain architectures that encode specific cellular outcomes. The identification of SUMOylated proteins and their modification sites has historically been challenging due to the low abundance of SUMOylation and the complexity of SUMO remnants after proteolysis. Recent advances in proteomics have led to the development of enrichment strategies and mass spectrometry (MS)-based methods that now enable the site-specific mapping of SUMO modifications. This chapter provides an overview of the biological roles and structural diversity of SUMOylation, and presents an MS-based workflow designed to identify SUMOylation sites with high specificity and depth. These tools offer new opportunities to dissect the SUMO-modified proteome in health and disease.