8E1M

Cryo-EM structure of the endogenous core TIM23 complex from S. cerevisiae


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Resolution: 2.90 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

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This is version 1.3 of the entry. See complete history


Literature

Structural basis of mitochondrial protein import by the TIM23 complex.

Sim, S.I.Chen, Y.Lynch, D.L.Gumbart, J.C.Park, E.

(2023) Nature 621: 620-626

  • DOI: https://doi.org/10.1038/s41586-023-06239-6
  • Primary Citation of Related Structures:  
    8E1M, 8SCX

  • PubMed Abstract: 

    Mitochondria import nearly all of their approximately 1,000-2,000 constituent proteins from the cytosol across their double-membrane envelope 1-5 . Genetic and biochemical studies have shown that the conserved protein translocase, termed the TIM23 complex, mediates import of presequence-containing proteins (preproteins) into the mitochondrial matrix and inner membrane. Among about ten different subunits of the TIM23 complex, the essential multipass membrane protein Tim23, together with the evolutionarily related protein Tim17, has long been postulated to form a protein-conducting channel 6-11 . However, the mechanism by which these subunits form a translocation path in the membrane and enable the import process remains unclear due to a lack of structural information. Here we determined the cryo-electron microscopy structure of the core TIM23 complex (heterotrimeric Tim17-Tim23-Tim44) from Saccharomyces cerevisiae. Contrary to the prevailing model, Tim23 and Tim17 themselves do not form a water-filled channel, but instead have separate, lipid-exposed concave cavities that face in opposite directions. Our structural and biochemical analyses show that the cavity of Tim17, but not Tim23, forms the protein translocation path, whereas Tim23 probably has a structural role. The results further suggest that, during translocation of substrate polypeptides, the nonessential subunit Mgr2 seals the lateral opening of the Tim17 cavity to facilitate the translocation process. We propose a new model for the TIM23-mediated protein import and sorting mechanism, a central pathway in mitochondrial biogenesis.


  • Organizational Affiliation

    Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Mitochondrial import inner membrane translocase subunit TIM17158Saccharomyces cerevisiaeMutation(s): 0 
Membrane Entity: Yes 
UniProt
Find proteins for P39515 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
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Go to UniProtKB:  P39515
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UniProt GroupP39515
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Mitochondrial import inner membrane translocase subunit TIM23222Saccharomyces cerevisiaeMutation(s): 0 
Membrane Entity: Yes 
UniProt
Find proteins for P32897 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
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Go to UniProtKB:  P32897
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UniProt GroupP32897
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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
Mitochondrial import inner membrane translocase subunit TIM44431Saccharomyces cerevisiaeMutation(s): 0 
Membrane Entity: Yes 
UniProt
Find proteins for Q01852 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
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Go to UniProtKB:  Q01852
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UniProt GroupQ01852
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Entity ID: 4
MoleculeChains Sequence LengthOrganismDetailsImage
Antibody Fab fragment light chainD [auth L]238Mus musculusMutation(s): 0 
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Entity ID: 5
MoleculeChains Sequence LengthOrganismDetailsImage
Antibody Fab fragment heavy chainE [auth H]238Mus musculusMutation(s): 0 
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Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Resolution: 2.90 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 
EM Software:
TaskSoftware PackageVersion
RECONSTRUCTIONcryoSPARC2.15

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Other privateUnited States--

Revision History  (Full details and data files)

  • Version 1.0: 2023-06-21
    Type: Initial release
  • Version 1.1: 2023-07-05
    Changes: Database references
  • Version 1.2: 2023-10-04
    Changes: Data collection, Database references
  • Version 1.3: 2024-10-09
    Changes: Data collection, Structure summary