A cryptic K48 ubiquitin chain binding site on UCH37 is required for its role in proteasomal degradation
Year: 2022
Type: article
Abstract: Degradation by the 26 S proteasome is an intricately regulated process fine tuned by the precise nature of ubiquitin modifications attached to a protein substrate. By debranching ubiquitin chains composed of K48 linkages, the proteasome-associated ubiquitin C-terminal hydrolase UCHL5/UCH37 serves as a positive regulator of protein degradation. How UCH37 achieves specificity for K48 chains is unclear. Here, we use a combination of hydrogen-deuterium mass spectrometry, chemical crosslinking, small-angle X-ray scattering, nuclear magnetic resonance (NMR), molecular docking, and targeted mutagenesis to uncover a cryptic K48 ubiquitin (Ub) chain-specific binding site on the opposite face of UCH37 relative to the canonical S1 (cS1) ubiquitin-binding site. Biochemical assays demonstrate the K48 chain-specific binding site is required for chain debranching and proteasome-mediated degradation of proteins modified with branched chains. Using quantitative proteomics, translation shutoff experiments, and linkage-specific affinity tools, we then identify specific proteins whose degradation depends on the debranching activity of UCH37. Our findings suggest that UCH37 and potentially other DUBs could use more than one S1 site to perform different biochemical functions.
Source: eLife
DOI: 10.7554/elife.76100
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,500
Awards: WIDE-BORE 9.4 TESLA NMR SPECTROMETER FOR UW-MADISON, Upgrade of the NMRFAM 750 MHz NMR Spectrometer, DEFINING THE FUNCTION OF PROTEASOMAL DEUBIQUITINASES, Acquisition of an Orbitrap MS, National Biomedical NMR Resource at Madison, Integrated state-of-the-art LC-MS/NMR system for the University of Wisconsin, National Biomedical NMR Resource at Madison, CONSOLE UPGRADES FOR NMR FACILITY, Chemistry Biology Interface Predoctoral Training Grant, NMR Spectrometer System Optimized for Direct 13C or 15N Detection, NMR User Program at NMRFAM, Chemistry-Biology Interface Predoctoral Training Grant, NMR Technologies for Integrating Structure, Function and Disease
OpenAlex ID: W4226160697