Covalent Inhibition of Ubc13 Affects Ubiquitin Signaling and Reveals Active Site Elements Important for Targeting.

ABSTRACT: Ubc13 is an E2 ubiquitin conjugating enzyme that functions in nuclear DNA damage signaling and cytoplasmic NF-?B signaling. Here, we present the structures of complexes of Ubc13 with two inhibitors, NSC697923 and BAY 11-7082, which inhibit DNA damage and NF-?B signaling in human cells. NSC697923 and BAY 11-7082 both inhibit Ubc13 by covalent adduct formation through a Michael addition at the Ubc13 active site cysteine. The resulting adducts of both compounds exploit a binding groove unique to Ubc13. We developed a Ubc13 mutant which resists NSC697923 inhibition and, using this mutant, we show that the inhibition of cellular DNA damage and NF-?B signaling by NSC697923 is largely due to specific Ubc13 inhibition. We propose that unique structural features near the Ubc13 active site could provide a basis for the rational development and design of specific Ubc13 inhibitors.

SUBMITTER: Hodge CD 

PROVIDER: S-EPMC4506735 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature