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-Structure paper
| タイトル | Structures of the 26 proteasome in complex with the Hsp70 co-chaperone Bag1 reveal a mechanism for direct substrate transfer. |
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| ジャーナル・号・ページ | Sci Adv, Vol. 12, Issue 8, Page eadz3026, Year 2026 |
| 掲載日 | 2026年2月20日 |
著者 | Moisés Maestro-López / Tat Cheung Cheng / Jimena Muntaner / Margarita Menéndez / Melissa Alonso / Andreas Schweitzer / Masato Ishizaka / Robert J Tomko / Jorge Cuéllar / José María Valpuesta / Eri Sakata / ![]() |
| PubMed 要旨 | Coupling between the chaperone and degradation systems, particularly under stress, is essential for eliminating unfolded proteins. The co-chaperone Bag1 links Hsp70 to the 26 proteasome, recruiting ...Coupling between the chaperone and degradation systems, particularly under stress, is essential for eliminating unfolded proteins. The co-chaperone Bag1 links Hsp70 to the 26 proteasome, recruiting Hsp70-bound clients for proteasomal degradation. Here, we present cryo-electron microscopy structures of the Bag1-bound 26 proteasome, revealing unprecedented conformational rearrangements within the 19 regulatory particle. Bag1 binding to the Rpn1 induces a marked reconfiguration of AAA adenosine triphosphatase (ATPase) ring, disrupting its canonical spiral staircase and remodeling the central channel architecture. This reconfiguration generates a large cavity above the substrate entry gate of the 20 core particle. The conserved pore-2 loops of ATPases Rpt2 and Rpt5 play critical roles in opening of the 20 gate, enabling substrate entry into proteolytic chamber independently of ubiquitination. These findings suggest a previously unknown mechanism of the proteasomal degradation, by which remodeling the central cavity and 20 gate in the presence of Bag1, possibly bypassing the need for ubiquitination. |
リンク | Sci Adv / PubMed:41719407 / PubMed Central |
| 手法 | EM (単粒子) |
| 解像度 | 3.5 - 6.2 Å |
| 構造データ | EMDB-52097, PDB-9heu: EMDB-52193: Co-chaperone Bag1-bound human 26S proteasome in SBAG2 state EMDB-52194: Co-chaperone Bag1-bound human 26S proteasome in SBAG3 state ![]() EMDB-52195: Hsp70-NBD:Bag1:Rpn1 ternary complex class 1 ![]() EMDB-52196: Hsp70-NBD:Bag1:Rpn1 ternary complex class 2 ![]() EMDB-53945: Co-chaperone Bag1-bound human 26S proteasome in SBag2 state |
| 化合物 | ![]() ChemComp-ATP: ![]() ChemComp-ADP: |
| 由来 |
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キーワード | HYDROLASE / Protein degradation / protease / AAA+ ATPase / Hsp70 / cochaperone / Bag1 / Complex / ubiquitin |
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