National Center for
5F6V: Crystal Structure Of Ubc9 (k48/k49a/e54a) Complexed With Fragment 1 (biphenol From Fragment Cocktail Screen)
Angew. Chem. Int. Ed. Engl. (2016) 55 p.5703-5707
Conjugation of the small ubiquitin-like modifier (SUMO) to protein substrates is an important disease-associated posttranslational modification, although few inhibitors of this process are known. Herein, we report the discovery of an allosteric small-molecule binding site on Ubc9, the sole SUMO E2 enzyme. An X-ray crystallographic screen was used to identify two distinct small-molecule fragments that bind to Ubc9 at a site distal to its catalytic cysteine. These fragments and related compounds inhibit SUMO conjugation in biochemical assays with potencies of 1.9-5.8 mm. Mechanistic and biophysical analyses, coupled with molecular dynamics simulations, point toward ligand-induced rigidification of Ubc9 as a mechanism of inhibition.