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Yorodumi- PDB-9h55: Assembly intermediate of human mitochondrial ribosome small subun... -
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Open data
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Basic information
| Entry | Database: PDB / ID: 9h55 | ||||||||||||||||||||||||
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| Title | Assembly intermediate of human mitochondrial ribosome small subunit in complex with NOA1 and TFB1M (state N3) | ||||||||||||||||||||||||
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Keywords | RIBOSOME / mitochondria / small subunit / assembly / NOA1 | ||||||||||||||||||||||||
| Function / homology | Function and homology informationrRNA modification in the mitochondrion / mitochondrial small ribosomal subunit assembly / mitochondrial transcription factor activity / transcription initiation at mitochondrial promoter / rRNA modification / rRNA (adenine-N6,N6-)-dimethyltransferase activity / RNA folding chaperone / mitochondrial ribosome assembly / Mitochondrial translation elongation / Mitochondrial translation initiation ...rRNA modification in the mitochondrion / mitochondrial small ribosomal subunit assembly / mitochondrial transcription factor activity / transcription initiation at mitochondrial promoter / rRNA modification / rRNA (adenine-N6,N6-)-dimethyltransferase activity / RNA folding chaperone / mitochondrial ribosome assembly / Mitochondrial translation elongation / Mitochondrial translation initiation / Mitochondrial ribosome-associated quality control / S-adenosyl-L-methionine binding / Mitochondrial translation termination / rRNA methylation / mitochondrial ribosome / mitochondrial small ribosomal subunit / mitochondrial translation / apoptotic mitochondrial changes / mitochondrial nucleoid / ribosomal small subunit binding / sperm head-tail coupling apparatus / Mitochondrial protein degradation / Transferases; Transferring one-carbon groups; Methyltransferases / mitochondrion organization / apoptotic signaling pathway / Transcriptional activation of mitochondrial biogenesis / rRNA processing / cell junction / regulation of translation / small ribosomal subunit / small ribosomal subunit rRNA binding / nuclear membrane / Hydrolases; Acting on acid anhydrides; Acting on GTP to facilitate cellular and subcellular movement / tRNA binding / cell population proliferation / mitochondrial inner membrane / rRNA binding / structural constituent of ribosome / ribosome / translation / mitochondrial matrix / protein domain specific binding / mRNA binding / GTPase activity / apoptotic process / GTP binding / nucleolus / mitochondrion / DNA binding / RNA binding / nucleoplasm / plasma membrane / cytoplasm / cytosol Similarity search - Function | ||||||||||||||||||||||||
| Biological species | Homo sapiens (human) | ||||||||||||||||||||||||
| Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.4 Å | ||||||||||||||||||||||||
Authors | Singh, V. / Shiriaev, D. / Khawaja, A. / Rorbach, J. | ||||||||||||||||||||||||
| Funding support | Sweden, 2items
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Citation | Journal: Nat Commun / Year: 2026Title: Pseudouridine synthase PUS1 and initiation factor mtIF2 are human mitoribosomal small subunit assembly factors. Authors: Vivek Singh / Dmitrii Shiriaev / Lorina Bilalli / Anas Khawaja / Joanna Rorbach / ![]() Abstract: Assembly of the mitochondrial ribosome (mitoribosome) is a crucial step in mitochondrial gene expression. This process facilitates mitochondrial translation, which produces essential subunits of the ...Assembly of the mitochondrial ribosome (mitoribosome) is a crucial step in mitochondrial gene expression. This process facilitates mitochondrial translation, which produces essential subunits of the oxidative phosphorylation machinery-the cell's primary energy-producing machinery. Disruptions in mitoribosome assembly can lead to severe human diseases. Given its fundamental importance, detailed structural analysis of mitoribosome assembly pathways is essential for advancing our understanding of mitochondrial function in both health and disease. In this study, we characterize twelve distinct assembly states of the mitoribosomal small subunit (mtSSU) isolated from human cells. Our findings reveal the intricate details of the final maturation stages of the mtSSU platform, decoding center, and the 3'-end of 12S rRNA. This process is governed by coordinated actions of assembly factors that ensure precise, stepwise rRNA folding and the integration of mitoribosomal proteins into the developing subunit. Our approach identifies pseudouridine synthase PUS1 and initiation factor mtIF2 as assembly factors, expanding their known roles beyond mt-tRNA maturation and translation, respectively. In addition, the identified assembly intermediates provide insight into the modular nature of mtSSU biogenesis in mitochondria and further link late-stage assembly to the acquisition of translational competence. | ||||||||||||||||||||||||
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Structure visualization
| Structure viewer | Molecule: Molmil Jmol/JSmol |
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Downloads & links
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Download
| PDBx/mmCIF format | 9h55.cif.gz | 3 MB | Display | PDBx/mmCIF format |
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| PDB format | pdb9h55.ent.gz | Display | PDB format | |
| PDBx/mmJSON format | 9h55.json.gz | Tree view | PDBx/mmJSON format | |
| Others | Other downloads |
-Validation report
| Arichive directory | https://data.pdbj.org/pub/pdb/validation_reports/h5/9h55 ftp://data.pdbj.org/pub/pdb/validation_reports/h5/9h55 | HTTPS FTP |
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-Related structure data
| Related structure data | ![]() 51877MC ![]() 51874 ![]() 9h51C ![]() 9h52C ![]() 9h54C ![]() 9rorC ![]() 9rotC ![]() 9rovC ![]() 9rpfC M: map data used to model this data C: citing same article ( |
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| Similar structure data | Similarity search - Function & homology F&H Search |
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Links
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Assembly
| Deposited unit | ![]()
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Components
-RNA chain , 1 types, 1 molecules A
| #1: RNA chain | Mass: 306449.312 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Production host: Homo sapiens (human) / References: GenBank: 1858621102 |
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+28S ribosomal protein ... , 25 types, 25 molecules BCDEFGHIJKLMNOPRSTUVWXYZ1
-Small ribosomal subunit protein ... , 2 types, 2 molecules Q0
| #17: Protein | Mass: 10659.494 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: MRPS21, RPMS21, MDS016 / Production host: Homo sapiens (human) / References: UniProt: P82921 |
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| #27: Protein | Mass: 25336.084 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: MRPS34 / Production host: Homo sapiens (human) / References: UniProt: P82930 |
-Protein , 4 types, 4 molecules 495a
| #29: Protein | Mass: 78648.547 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: PTCD3, MRPS39, TRG15 / Production host: Homo sapiens (human) / References: UniProt: Q96EY7 |
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| #30: Protein | Mass: 78565.758 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: NOA1, C4orf14 / Production host: Homo sapiens (human) / References: UniProt: Q8NC60 |
| #31: Protein | Mass: 39600.953 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: TFB1M, CGI-75 / Production host: Homo sapiens (human)References: UniProt: Q8WVM0, Transferases; Transferring one-carbon groups; Methyltransferases |
| #32: Protein | Mass: 38417.434 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: RBFA, C18orf22 / Production host: Homo sapiens (human) / References: UniProt: Q8N0V3 |
-Non-polymers , 6 types, 57 molecules 










| #33: Chemical | ChemComp-MG / #34: Chemical | ChemComp-K / #35: Chemical | ChemComp-ZN / | #36: Chemical | #37: Chemical | ChemComp-ATP / | #38: Chemical | |
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-Details
| Has ligand of interest | N |
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| Has protein modification | Y |
-Experimental details
-Experiment
| Experiment | Method: ELECTRON MICROSCOPY |
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| EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
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Sample preparation
| Component | Name: mitoribosomal small subunit assembly intermediate / Type: RIBOSOME / Entity ID: #1-#18, #21-#32 / Source: NATURAL |
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| Source (natural) | Organism: Homo sapiens (human) |
| Buffer solution | pH: 7.5 |
| Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
| Vitrification | Cryogen name: ETHANE |
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Electron microscopy imaging
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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| Microscopy | Model: FEI TITAN KRIOS |
| Electron gun | Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM |
| Electron lens | Mode: BRIGHT FIELD / Nominal defocus max: 1800 nm / Nominal defocus min: 400 nm |
| Image recording | Electron dose: 45 e/Å2 / Film or detector model: GATAN K3 (6k x 4k) |
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Processing
| EM software | Name: PHENIX / Version: 1.20.1_4487: / Category: model refinement | ||||||||||||||||||||||||
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| CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||
| 3D reconstruction | Resolution: 3.4 Å / Resolution method: FSC 0.5 CUT-OFF / Num. of particles: 16018 / Symmetry type: POINT | ||||||||||||||||||||||||
| Refine LS restraints |
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About Yorodumi



Homo sapiens (human)
Sweden, 2items
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FIELD EMISSION GUN