Identification of PIAS1-direct interacting proteins through DSP-based crosslinking

As a conserved post-translational modification, SUMOylation has been shown to play important roles in chromatin related biological processes including transcription. However, how the SUMOylation machinery associates with chromatin is not clear. To underatand how nuclear matrix associated SUMO enzymes regulate chromatin related function, we attempted to identify the direct interacting proteins of PIAS1, a major SUMO E3 protein. We made use of the crosslinking reagent dithiobis succinimidyl propionate (DSP), which is a water-insoluble, membrane-permeable homobifunctional N-hydroxysuccimide ester that can reversibly cross-link different proteins by primary amines in cells.