Oxidation of catalytic cysteine of human deubiquitinase BAP1 triggers misfolding and aggregation in addition to functional loss

Deubiquitinating enzymes (DUBs) form a large protease family involved in a myriad of biological and pathological processes, including ROS sensors. ROS-mediated inhibition of their DUB activities is critical for fine-tuning the stress-activated signaling pathways. Here, we demonstrate that the ubiquitin C-terminal hydrolase (UCH) domain of BAP1 (BAP1-UCH) is highly sensitive to moderate oxidative stress. Oxidation of the catalytic C91 significantly destabilizes BAP1-UCH and increases the population of partially unfolded form, which is prone to aggregation. Unlike other DUBs, the oxidation-induced structural and functional loss of BAP1-UCH cannot be fully reversed by reducing agents. The oligomerization of oxidized BAP1-UCH is attributed to inter-molecular disulfide bond formation. Hydrogendeuterium mass exchange spectrometry (HDX-MS) reveals increased fluctuations of the central bsheet upon oxidation. Our findings suggest that oxidation-mediated functional loss and increased aggregation propensity may contribute to oncogenesis associated with BAP1. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study demonstrates that the ubiquitin C-terminal hydrolase (UCH) domain of BAP1 is highly sensitive to moderate oxidative stress. Partial oxidation of BAP1-UCH destabilizes its structure and increases aggregation propensity, and unlike other DUBs, the oxidative structural and functional loss of BAP1-UCH cannot be fully reversed by reducing agents. The oligomerization of oxidized BAP1-UCH is attributed to inter-molecular disulfide bond formation. Increased fluctuations of the central β sheet upon oxidation are revealed by hydrogen-deuterium exchange mass spectrometry (HDX-MS). These findings may contribute to understanding the oncogenesis associated with BAP1.