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Yorodumi- EMDB-63776: Substrate-engaged human 26S proteasome bound to midnolin with RPT... -
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Basic information
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| Title | Substrate-engaged human 26S proteasome bound to midnolin with RPT1 at top of spiral staircase | |||||||||
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Keywords | Midnolin / 26S proteasome / Complex / HYDROLASE | |||||||||
| Function / homology | Function and homology informationnegative regulation of glucokinase activity / thyrotropin-releasing hormone receptor binding / nuclear proteasome complex / host-mediated perturbation of viral transcription / Impaired BRCA2 translocation to the nucleus / Impaired BRCA2 binding to SEM1 (DSS1) / positive regulation of inclusion body assembly / proteasome accessory complex / meiosis I / integrator complex ...negative regulation of glucokinase activity / thyrotropin-releasing hormone receptor binding / nuclear proteasome complex / host-mediated perturbation of viral transcription / Impaired BRCA2 translocation to the nucleus / Impaired BRCA2 binding to SEM1 (DSS1) / positive regulation of inclusion body assembly / proteasome accessory complex / meiosis I / integrator complex / purine ribonucleoside triphosphate binding / proteasome regulatory particle / cytosolic proteasome complex / positive regulation of proteasomal protein catabolic process / proteasome-activating activity / Antigen processing: Ub, ATP-independent proteasomal degradation / proteasome regulatory particle, lid subcomplex / proteasome regulatory particle, base subcomplex / sperm glycocalyx / protein K63-linked deubiquitination / negative regulation of programmed cell death / metal-dependent deubiquitinase activity / Regulation of ornithine decarboxylase (ODC) / Proteasome assembly / proteasome core complex / perinuclear theca / Cross-presentation of soluble exogenous antigens (endosomes) / K63-linked deubiquitinase activity / Somitogenesis / transcription factor binding / Homologous DNA Pairing and Strand Exchange / Defective homologous recombination repair (HRR) due to BRCA1 loss of function / Defective HDR through Homologous Recombination Repair (HRR) due to PALB2 loss of BRCA1 binding function / Defective HDR through Homologous Recombination Repair (HRR) due to PALB2 loss of BRCA2/RAD51/RAD51C binding function / Resolution of D-loop Structures through Synthesis-Dependent Strand Annealing (SDSA) / Resolution of D-loop Structures through Holliday Junction Intermediates / proteasome binding / Impaired BRCA2 binding to RAD51 / myofibril / regulation of protein catabolic process / proteasome storage granule / proteasomal ubiquitin-independent protein catabolic process / sperm head-tail coupling apparatus / general transcription initiation factor binding / Presynaptic phase of homologous DNA pairing and strand exchange / blastocyst development / protein deubiquitination / polyubiquitin modification-dependent protein binding / immune system process / proteasome endopeptidase complex / NF-kappaB binding / proteasome core complex, beta-subunit complex / endopeptidase activator activity / threonine-type endopeptidase activity / proteasome assembly / mRNA export from nucleus / proteasome core complex, alpha-subunit complex / enzyme regulator activity / regulation of proteasomal protein catabolic process / inclusion body / TBP-class protein binding / : / ciliary tip / proteasome complex / stem cell differentiation / Regulation of activated PAK-2p34 by proteasome mediated degradation / sarcomere / Autodegradation of Cdh1 by Cdh1:APC/C / APC/C:Cdc20 mediated degradation of Securin / ubiquitin binding / Asymmetric localization of PCP proteins / N-glycan trimming in the ER and Calnexin/Calreticulin cycle / Ubiquitin-dependent degradation of Cyclin D / SCF-beta-TrCP mediated degradation of Emi1 / NIK-->noncanonical NF-kB signaling / AUF1 (hnRNP D0) binds and destabilizes mRNA / TNFR2 non-canonical NF-kB pathway / centriole / sperm end piece / negative regulation of inflammatory response to antigenic stimulus / P-body / Assembly of the pre-replicative complex / Vpu mediated degradation of CD4 / Cdc20:Phospho-APC/C mediated degradation of Cyclin A / lipopolysaccharide binding / Dectin-1 mediated noncanonical NF-kB signaling / Degradation of DVL / Degradation of AXIN / Degradation of CRY and PER proteins / Hh mutants are degraded by ERAD / Activation of NF-kappaB in B cells / G2/M Checkpoints / Degradation of GLI1 by the proteasome / Hedgehog ligand biogenesis / Regulation of RUNX3 expression and activity / Autodegradation of the E3 ubiquitin ligase COP1 / Defective CFTR causes cystic fibrosis / GSK3B and BTRC:CUL1-mediated-degradation of NFE2L2 / Negative regulation of NOTCH4 signaling / APC/C:Cdh1 mediated degradation of Cdc20 and other APC/C:Cdh1 targeted proteins in late mitosis/early G1 Similarity search - Function | |||||||||
| Biological species | Homo sapiens (human) | |||||||||
| Method | single particle reconstruction / cryo EM / Resolution: 2.75 Å | |||||||||
Authors | Zhu C / Qin L / Liang L | |||||||||
| Funding support | China, 1 items
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Citation | Journal: Nat Commun / Year: 2026Title: Structural dynamics of the midnolin-proteasome during ubiquitin-independent substrate turnover. Authors: Chuanda Zhu / Lu Qin / Zonglin Dai / Peng Zuo / Ao Yang / Lijun Zhong / Zhiqiang Lin / Ling Liang / ![]() Abstract: The 26S proteasome typically degrades proteins marked by ubiquitin chains. However, a distinct, ubiquitin-independent degradation pathway for nuclear proteins exists, mediated by the adaptor protein ...The 26S proteasome typically degrades proteins marked by ubiquitin chains. However, a distinct, ubiquitin-independent degradation pathway for nuclear proteins exists, mediated by the adaptor protein midnolin, yet its molecular mechanism remains poorly understood. Here, we present nine cryo-electron microscopy structures of the human 26S proteasome in complex with midnolin, which collectively delineate a near-complete catalytic cycle. Our structures reveal that midnolin binds to the proteasome via the RPN1 subunit by its C-terminal helix. Unexpectedly, its ubiquitin-like domain interacts with the RPN11 deubiquitinase in a non-catalytic role. This interaction positions the adjacent Catch domain, which is responsible for substrate binding, directly above the proteasomal entrance, potentially facilitating substrate entry into the proteasome. Furthermore, we observe four consecutive spiral staircase conformations of the AAA+ ATPase hexamer during substrate translocation. These findings provide insights into the mechanisms underlying ubiquitin-independent nuclear protein degradation and may help develop strategies for targeting nuclear proteins via direct proteasomal degradation. | |||||||||
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Structure visualization
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Downloads & links
-EMDB archive
| Map data | emd_63776.map.gz | 743 MB | EMDB map data format | |
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| Header (meta data) | emd-63776-v30.xml emd-63776.xml | 67.8 KB 67.8 KB | Display Display | EMDB header |
| Images | emd_63776.png | 53.2 KB | ||
| Filedesc metadata | emd-63776.cif.gz | 15.4 KB | ||
| Archive directory | http://ftp.pdbj.org/pub/emdb/structures/EMD-63776 ftp://ftp.pdbj.org/pub/emdb/structures/EMD-63776 | HTTPS FTP |
-Related structure data
| Related structure data | ![]() 9mbpMC ![]() 22mmC ![]() 9mboC ![]() 9mbqC ![]() 9u3lC ![]() 9u4mC ![]() 9u7rC ![]() 9w39C ![]() 9wbgC C: citing same article ( M: atomic model generated by this map |
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| Similar structure data | Similarity search - Function & homology F&H Search |
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Links
| EMDB pages | EMDB (EBI/PDBe) / EMDataResource |
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| Related items in Molecule of the Month |
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Map
| File | Download / File: emd_63776.map.gz / Format: CCP4 / Size: 824 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES) | ||||||||||||||||||||||||||||||||||||
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| Projections & slices | Image control
Images are generated by Spider. | ||||||||||||||||||||||||||||||||||||
| Voxel size | X=Y=Z: 0.85 Å | ||||||||||||||||||||||||||||||||||||
| Density |
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| Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||
| Details | EMDB XML:
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-Supplemental data
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Sample components
+Entire : 26S proteasome complexed with midnolin
+Supramolecule #1: 26S proteasome complexed with midnolin
+Supramolecule #2: midnolin
+Supramolecule #3: 26S proteasome
+Macromolecule #1: 26S proteasome non-ATPase regulatory subunit 1
+Macromolecule #2: 26S proteasome non-ATPase regulatory subunit 3
+Macromolecule #3: 26S proteasome non-ATPase regulatory subunit 12
+Macromolecule #4: 26S proteasome non-ATPase regulatory subunit 11
+Macromolecule #5: 26S proteasome non-ATPase regulatory subunit 6
+Macromolecule #6: 26S proteasome non-ATPase regulatory subunit 7
+Macromolecule #7: 26S proteasome non-ATPase regulatory subunit 13
+Macromolecule #8: 26S proteasome non-ATPase regulatory subunit 4
+Macromolecule #9: 26S proteasome non-ATPase regulatory subunit 14
+Macromolecule #10: 26S proteasome non-ATPase regulatory subunit 8
+Macromolecule #11: 26S proteasome complex subunit SEM1
+Macromolecule #12: 26S proteasome regulatory subunit 7
+Macromolecule #13: 26S proteasome regulatory subunit 4
+Macromolecule #14: 26S proteasome regulatory subunit 8
+Macromolecule #15: 26S proteasome regulatory subunit 6B
+Macromolecule #16: Proteasome 26S subunit, ATPase 6
+Macromolecule #17: 26S proteasome regulatory subunit 6A
+Macromolecule #18: substrate peptide
+Macromolecule #19: Proteasome subunit alpha type-6
+Macromolecule #20: Proteasome subunit alpha type-2
+Macromolecule #21: Proteasome subunit alpha type-4
+Macromolecule #22: Proteasome subunit alpha type-7
+Macromolecule #23: Proteasome subunit alpha type-5
+Macromolecule #24: Isoform Long of Proteasome subunit alpha type-1
+Macromolecule #25: Proteasome subunit alpha type-3
+Macromolecule #26: Proteasome subunit beta type-6
+Macromolecule #27: Proteasome subunit beta type-7
+Macromolecule #28: Proteasome subunit beta type-3
+Macromolecule #29: Proteasome subunit beta type-2
+Macromolecule #30: Proteasome subunit beta type-5
+Macromolecule #31: Proteasome subunit beta type-1
+Macromolecule #32: Proteasome subunit beta type-4
+Macromolecule #33: Midnolin
+Macromolecule #34: 26S proteasome non-ATPase regulatory subunit 2
+Macromolecule #35: ZINC ION
+Macromolecule #36: ADENOSINE-5'-TRIPHOSPHATE
+Macromolecule #37: MAGNESIUM ION
+Macromolecule #38: ADENOSINE-5'-DIPHOSPHATE
+Macromolecule #39: N-[(benzyloxy)carbonyl]-L-leucyl-N-[(2S)-4-methyl-1-oxopentan-2-y...
-Experimental details
-Structure determination
| Method | cryo EM |
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Processing | single particle reconstruction |
| Aggregation state | particle |
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Sample preparation
| Buffer | pH: 7.4 |
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| Vitrification | Cryogen name: ETHANE |
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Electron microscopy
| Microscope | TFS KRIOS |
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| Image recording | Film or detector model: GATAN K3 (6k x 4k) / Average electron dose: 40.0 e/Å2 |
| Electron beam | Acceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN |
| Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Nominal defocus max: 1.8 µm / Nominal defocus min: 1.2 µm |
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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About Yorodumi



Keywords
Homo sapiens (human)
Authors
China, 1 items
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Processing
FIELD EMISSION GUN
