8USB image
Entry Detail
PDB ID:
8USB
EMDB ID:
Title:
Non-substrate-engaged human 26S proteasome with Nub1/FAT10 bound to Rpn1
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2023-10-27
Release Date:
2024-11-06
Method Details:
Experimental Method:
Resolution:
2.73 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:26S proteasome regulatory subunit 7
Chain IDs:H (auth: A)
Chain Length:376
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome regulatory subunit 4
Chain IDs:G (auth: B)
Chain Length:440
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S protease regulatory subunit 8
Chain IDs:B (auth: C)
Chain Length:406
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome regulatory subunit 6B
Chain IDs:I (auth: D)
Chain Length:418
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S protease regulatory subunit 10B
Chain IDs:J (auth: E)
Chain Length:70
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome regulatory subunit 6A
Chain IDs:K (auth: F)
Chain Length:439
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Proteasome subunit alpha type-6
Chain IDs:L (auth: G)
Chain Length:605
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Proteasome subunit alpha type-2
Chain IDs:M (auth: H)
Chain Length:234
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Proteasome subunit alpha type-4
Chain IDs:N (auth: I)
Chain Length:261
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Proteasome subunit alpha type-7
Chain IDs:O (auth: J)
Chain Length:248
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Proteasome subunit alpha type-5
Chain IDs:P (auth: K)
Chain Length:241
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Proteasome subunit alpha type-1
Chain IDs:Q (auth: L)
Chain Length:263
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Proteasome subunit alpha type-3
Chain IDs:R (auth: M)
Chain Length:255
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Proteasome subunit beta type-7
Chain IDs:S (auth: O)
Chain Length:277
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 1
Chain IDs:T (auth: U)
Chain Length:953
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 3
Chain IDs:U (auth: V)
Chain Length:534
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 12
Chain IDs:A (auth: W)
Chain Length:456
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 11
Chain IDs:AA (auth: X)
Chain Length:422
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 6
Chain IDs:X (auth: Y)
Chain Length:389
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 7
Chain IDs:Y (auth: Z)
Chain Length:324
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 13
Chain IDs:Z (auth: a)
Chain Length:376
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 4
Chain IDs:C (auth: b)
Chain Length:440
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 14
Chain IDs:V (auth: c)
Chain Length:406
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 8
Chain IDs:D (auth: d)
Chain Length:418
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome complex subunit SEM1
Chain IDs:W (auth: e)
Chain Length:70
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:26S proteasome non-ATPase regulatory subunit 2
Chain IDs:E (auth: f)
Chain Length:439
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:NEDD8 ultimate buster 1
Chain IDs:F (auth: g)
Chain Length:605
Number of Molecules:1
Biological Source:Homo sapiens
Primary Citation
NUB1 traps unfolded FAT10 for ubiquitin-independent degradation by the 26S proteasome.
Nat.Struct.Mol.Biol. ? ? ? (2025)
PMID: 40217121 DOI: 10.1038/s41594-025-01527-3

Abstact

The ubiquitin-like modifier FAT10 targets hundreds of proteins in the mammalian immune system to the 26S proteasome for degradation. This degradation pathway requires the cofactor NUB1, yet the underlying mechanisms remain unknown. Here, we reconstituted a minimal in vitro system with human components and revealed that NUB1 uses the intrinsic instability of FAT10 to trap its N-terminal ubiquitin-like domain in an unfolded state and deliver it to the 26S proteasome for engagement, allowing the degradation of FAT10-ylated substrates in a ubiquitin-independent and p97-independent manner. Using hydrogen-deuterium exchange, structural modeling and site-directed mutagenesis, we identified the formation of an intricate complex with FAT10 that activates NUB1 for docking to the 26S proteasome, and our cryo-EM studies visualized the highly dynamic NUB1 complex bound to the proteasomal Rpn1 subunit during FAT10 delivery and the early stages of ATP-dependent degradation. These findings identified a previously unknown mode of cofactor-mediated, ubiquitin-independent substrate delivery to the 26S proteasome that relies on trapping partially unfolded states for engagement by the proteasomal ATPase motor.

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