Reconstitution and Structural Analysis of a HECT Ligase-Ubiquitin Complex via an Activity-Based Probe

• Published in: ACS chemical biology Vol. 16; no. 9; pp. 1615 - 1621
• Main Authors: Nair, Rahul M, Seenivasan, Ayshwarya, Liu, Bing, Chen, Dan, Lowe, Edward D, Lorenz, Sonja
• Format: Journal Article
• Language: English
• Published: American Chemical Society 17.09.2021
• Subjects: Letters
• ISSN: 1554-8929; 1554-8937
• DOI: 10.1021/acschembio.1c00433

Ubiquitin activity-based probes have proven invaluable in elucidating structural mechanisms in the ubiquitin system by stabilizing transient macromolecular complexes of deubiquitinases, ubiquitin-activating enzymes, and the assemblies of ubiquitin-conjugating enzymes with ubiquitin ligases of the RING-Between-RING and RING-Cysteine-Relay families. Here, we demonstrate that an activity-based probe, ubiquitin-propargylamine, allows for the preparative reconstitution and structural analysis of the interactions between ubiquitin and certain HECT ligases. We present a crystal structure of the ubiquitin-linked HECT domain of HUWE1 that defines a catalytically critical conformation of the C-terminal tail of the ligase for the transfer of ubiquitin to an acceptor protein. Moreover, we observe that ubiquitin-propargylamine displays selectivity among HECT domains, thus corroborating the notion that activity-based probes may provide entry points for the development of specific, active site-directed inhibitors and reporters of HECT ligase activities.