Activity-Based Profiling Reveals Reactivity of the Murine Thymoproteasome-Specific Subunit beta 5t

作者：Florea Bogdan I^*; Verdoes Martijn; Li Nan; van der Linden Wouter A; Geurink Paul P; van den Elst Hans; Hofmann Tanja; de Ru Arnoud; van Veelen Peter A; Tanaka Keiji; Sasaki Katsuhiro; Murata Shigeo; den Dulk Hans; Brouwer Jaap; Ossendorp Ferry A; Kisselev Alexei F; Overkleeft Herman S

来源：Chemistry & Biology, 2010, 17(8): 795-801.

DOI：10.1016/j.chembiol.2010.05.027

Epithelial cells of the thymus cortex express a unique proteasome particle involved in positive T cell selection. This thymoproteasome contains the recently discovered beta 5t subunit that has an uncharted activity, if any. We synthesized fluorescent epoxomicin probes that were used in a chemical proteomics approach, entailing activity-based profiling, affinity purification, and LC-MS identification, to demonstrate that the beta 5t subunit is catalytically active in the murine thymus. A panel of established proteasome inhibitors showed that the broad-spectrum inhibitor epoxomicin blocks the beta 5t activity and that the subunit-specific antagonists bortezomib and NC005 do not inhibit beta 5t. We show that beta 5t has a substrate preference distinct from beta 5/beta 5i that might explain how the thymoproteasome generates the MHC class I peptide repertoire needed for positive T cell selection.

• 出版日期2010-8-27
• 单位河北医科大学