Chemical synthesis of diSUMO photoaffinity probes for the identification of PolySUMO chain-specific interacting proteins

Abstract

Small ubiquitin-like modifiers (SUMOs) are protein modifiers that can form polymeric chains. They are important signals in cellular processes, and their study and profiling require the development of molecular tools. Herein, the authors have reported an efficient chemical protein synthesis approach for the generation of dimeric SUMO-2-based photoaffinity probes through the ligation of four readily synthesizable peptides. Proteomic studies using this diSUMO-2 probe on HeLa cell nuclear lysate found it to capture a significantly different selection of proteins compared with its monoSUMO counterparts. This resulted in the identification of several previously unknown SUMO chain-specific interacting proteins such as 40S ribosomal protein S3, which showed a significantly higher affinity for polySUMO chains than monomeric SUMO. Collectively, these results emphasize the need to develop SUMO chain-based probes in other species, and to shed light on the important role of polySUMOylation in diseases.