Person:

Rhee, David

Differential gene expression is an essential component of the programs that give rise to specific cellular fates and functions. This differential regulation occurs primarily at the transcriptional level and is controlled by complex regulatory networks governed by the action of transcription factors at specific DNA regulatory elements. Transcription factors rarely act alone, often functioning through combinatorial interactions with other transcription factors, co-factors and chromatin-remodeling proteins. Defining these protein-protein interactions is an essential component to understanding transcription factor function and consequently, the cell as an integrated network.

N-terminal acetylation is an abundant modification influencing protein functions. Since ≈80% of mammalian cytosolic proteins are N-terminally acetylated, this potentially represents an untapped target for chemical control of their functions. Structural studies have revealed that, like lysine acetylation, N-terminal acetylation converts a positively charged amine into a hydrophobic handle that mediates protein interactions, suggesting it may be a druggable target. We report the development of chemical probes targeting the N-terminal acetylation-dependent interaction between an E2 conjugating enzyme (UBE2M, aka UBC12) and DCN1 (aka DCUN1D1), a subunit of a multiprotein E3 ligase for the ubiquitin-like protein NEDD8. The inhibitors are highly selective with respect to other protein acetyl amide binding sites, inhibit NEDD8 ligation in vitro and in cells, and suppress the anchorage-independent growth of a cell line harboring DCN1 amplification. Overall, the data demonstrate that N-terminal acetyl-dependent protein interactions are druggable targets, and provide insights into targeting multiprotein E2–E3 ligases.