EMD-17801
NEDD8-CUL2-RBX1-ELOB/C-FEM1C-SIL1 conformation 2
EMD-17801
Single-particle6.88 Å
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Map released: 14/02/2024
Last modified: 28/02/2024
Sample Organism:
Homo sapiens
Sample: NEDD8-CUL2-RBX1-ELOB/C-FEM1C-SIL1 conformation 2
Deposition Authors: Liwocha J
,
Prabu JR
,
Kleiger G
,
Schulman BA
Sample: NEDD8-CUL2-RBX1-ELOB/C-FEM1C-SIL1 conformation 2
Deposition Authors: Liwocha J
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Mechanism of millisecond Lys48-linked poly-ubiquitin chain formation by cullin-RING ligases.
Liwocha J
,
Li J
,
Purser N,
Rattanasopa C,
Maiwald S
,
Krist DT,
Scott DC,
Steigenberger B,
Prabu JR
,
Schulman BA
,
Kleiger G
(2024) Nat Struct Mol Biol , 31 , 378 - 389
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(2024) Nat Struct Mol Biol , 31 , 378 - 389
Abstract:
E3 ubiquitin ligases, in collaboration with E2 ubiquitin-conjugating enzymes, modify proteins with poly-ubiquitin chains. Cullin-RING ligase (CRL) E3s use Cdc34/UBE2R-family E2s to build Lys48-linked poly-ubiquitin chains to control an enormous swath of eukaryotic biology. Yet the molecular mechanisms underlying this exceptional linkage specificity and millisecond kinetics of poly-ubiquitylation remain unclear. Here we obtain cryogenic-electron microscopy (cryo-EM) structures that provide pertinent insight into how such poly-ubiquitin chains are forged. The CRL RING domain not only activates the E2-bound ubiquitin but also shapes the conformation of a distinctive UBE2R2 loop, positioning both the ubiquitin to be transferred and the substrate-linked acceptor ubiquitin within the active site. The structures also reveal how the ubiquitin-like protein NEDD8 uniquely activates CRLs during chain formation. NEDD8 releases the RING domain from the CRL, but unlike previous CRL-E2 structures, does not contact UBE2R2. These findings suggest how poly-ubiquitylation may be accomplished by many E2s and E3s.
E3 ubiquitin ligases, in collaboration with E2 ubiquitin-conjugating enzymes, modify proteins with poly-ubiquitin chains. Cullin-RING ligase (CRL) E3s use Cdc34/UBE2R-family E2s to build Lys48-linked poly-ubiquitin chains to control an enormous swath of eukaryotic biology. Yet the molecular mechanisms underlying this exceptional linkage specificity and millisecond kinetics of poly-ubiquitylation remain unclear. Here we obtain cryogenic-electron microscopy (cryo-EM) structures that provide pertinent insight into how such poly-ubiquitin chains are forged. The CRL RING domain not only activates the E2-bound ubiquitin but also shapes the conformation of a distinctive UBE2R2 loop, positioning both the ubiquitin to be transferred and the substrate-linked acceptor ubiquitin within the active site. The structures also reveal how the ubiquitin-like protein NEDD8 uniquely activates CRLs during chain formation. NEDD8 releases the RING domain from the CRL, but unlike previous CRL-E2 structures, does not contact UBE2R2. These findings suggest how poly-ubiquitylation may be accomplished by many E2s and E3s.