Thursday, May 16, 2019

Covalent Ligand Screening Uncovers a RNF4 E3 Ligase Recruiter for Targeted Protein Degradation Applications [@DanNomura]

Carl C. WardJordan I. KleinmanScott M. BrittainPatrick S. LeeClive Yik Sham ChungKenneth KimYana PetriJason R. ThomasJohn A. TallaricoJeffrey M. McKennaMarkus Schirle, and Daniel K. Nomura
ACS Chemical Biology 2019
DOI: 10.1021/acschembio.8b01083

Targeted protein degradation has arisen as a powerful strategy for drug discovery allowing the targeting of undruggable proteins for proteasomal degradation. This approach most often employs heterobifunctional degraders consisting of a protein-targeting ligand linked to an E3 ligase recruiter to ubiquitinate and mark proteins of interest for proteasomal degradation. One challenge with this approach, however, is that only a few E3 ligase recruiters currently exist for targeted protein degradation applications, despite the hundreds of known E3 ligases in the human genome. Here, we utilized activity-based protein profiling (ABPP)-based covalent ligand screening approaches to identify cysteine-reactive small-molecules that react with the E3 ubiquitin ligase RNF4 and provide chemical starting points for the design of RNF4-based degraders. The hit covalent ligand from this screen reacted with either of two zinc-coordinating cysteines in the RING domain, C132 and C135, with no effect on RNF4 activity. We further optimized the potency of this hit and incorporated this potential RNF4 recruiter into a bifunctional degrader linked to JQ1, an inhibitor of the BET family of bromodomain proteins. We demonstrate that the resulting compound CCW 28-3 is capable of degrading BRD4 in a proteasome- and RNF4-dependent manner. In this study, we have shown the feasibility of using chemoproteomics-enabled covalent ligand screening platforms to expand the scope of E3 ligase recruiters that can be exploited for targeted protein degradation applications.

Thiol Reactivity of N-Aryl α-Methylene-γ-lactams: Influence of the Guaianolide Structure [@KayBrummond]

 Daniel P. Dempe, Chong-Lei Ji, Peng Liu, and Kay M. Brummond The Journal of Organic Chemistry, 2020 DOI: 10.1021/acs.joc.2c01530 The α-meth...