Download MendeleyStructures of dynamic interactors at native proteasomes by PhIX-MS and cryo-electron microscopy.
Lee, K., Negi, H., Chen, X., Atallah-Yunes, K., Truslow, S., Castelino, R.E., Guest, M.R., Ciancone, A.M., Lu, X., Tarasov, S.G., Chari, R., Walters, K.J., O'Reilly, F.J.(2026) Mol Cell 86: 3067
- PubMed: 42476128 Search on PubMed
- DOI: https://doi.org/10.1016/j.molcel.2026.06.032
- Primary Citation Related Structures:
12BM, 9PMJ, 9PMO, 9PMQ, 9PRO, 9PRT - PubMed Abstract:
Molecular machines rely on dynamic, low-affinity interactions to perform their functional roles. We developed PhIX-MS (photo-induced in situ crosslinking-mass spectrometry), a structural proteomics workflow to capture topological information for such transient interactions in cells by UV-activated crosslinking. Applying PhIX-MS with cryo-electron microscopy (cryo-EM) to proteasomes, we mapped the redox sensor TXNL1 at the proteasome regulatory particle (RP), including its dynamic thioredoxin-like domain near RPN2/PSMD1 and RPN13/ADRM1, where it is ideal for reducing substrates prior to proteolysis. RPs without the proteolytic core particle (CP) were structurally resolved while bound to TXNL1 and/or the chaperone PSMD5/S5b, which inserts its C terminus into the ATPase pore, causing extensive structural rearrangements. Additionally, PhIX-MS and AlphaFold identified the ubiquitin ligase UBE3C/Hul5 at RPN2, RPN3, and a dynamic RPN10 region, tethering UBE3C above the substrate entry channel. Our integrative approach enables the localization of native, low-affinity protein interactions and is broadly applicable to dynamic macromolecular assemblies.
- Structural System Biology Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute (NCI), National Institutes of Health, Frederick, MD 21702-1201, USA.
Organizational Affiliation:
