Design of High-Throughput Screening Assays and Identification
of a SUMO1-Specific Small Molecule Chemotype Targeting the SUMO-Interacting
Motif-Binding Surface
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Abstract
Protein–protein
interactions are generally challenging to
target by small molecules. To address the challenge, we have used
a multidisciplinary approach to identify small-molecule disruptors
of protein–protein interactions that are mediated by SUMO (small
ubiquitin-like modifier) proteins. SUMO modifications have emerged
as a target with importance in treating cancer, neurodegenerative
disorders, and viral infections. It has been shown that inhibiting
SUMO-mediated protein–protein interactions can sensitize cancer
cells to chemotherapy and radiation. We have developed highly sensitive
assays using time-resolved fluorescence resonance energy transfer
(TR-FRET) and fluorescence polarization (FP) that were used for high-throughput
screening (HTS) to identify inhibitors for SUMO-dependent protein–protein
interactions. Using these assays, we have identified a nonpeptidomimetic
small molecule chemotype that binds to SUMO1 but not SUMO2 or 3. NMR
chemical shift perturbation studies have shown that the compounds
of this chemotype bind to the SUMO1 surface required for protein–protein
interaction, despite the high sequence similarity of SUMO1 and SUMO2
and 3 at this surface