6ENY

Structure of the human PLC editing module


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Resolution: 5.80 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

wwPDB Validation 3D Report Full Report



Literature

Structure of the human MHC-I peptide-loading complex.

Blees, A.Januliene, D.Hofmann, T.Koller, N.Schmidt, C.Trowitzsch, S.Moeller, A.Tampe, R.

(2017) Nature 551: 525-528

  • DOI: 10.1038/nature24627
  • Primary Citation of Related Structures:  
    6ENY

  • PubMed Abstract: 
  • The peptide-loading complex (PLC) is a transient, multisubunit membrane complex in the endoplasmic reticulum that is essential for establishing a hierarchical immune response. The PLC coordinates peptide translocation into the endoplasmic reticulum w ...

    The peptide-loading complex (PLC) is a transient, multisubunit membrane complex in the endoplasmic reticulum that is essential for establishing a hierarchical immune response. The PLC coordinates peptide translocation into the endoplasmic reticulum with loading and editing of major histocompatibility complex class I (MHC-I) molecules. After final proofreading in the PLC, stable peptide-MHC-I complexes are released to the cell surface to evoke a T-cell response against infected or malignant cells. Sampling of different MHC-I allomorphs requires the precise coordination of seven different subunits in a single macromolecular assembly, including the transporter associated with antigen processing (TAP1 and TAP2, jointly referred to as TAP), the oxidoreductase ERp57, the MHC-I heterodimer, and the chaperones tapasin and calreticulin. The molecular organization of and mechanistic events that take place in the PLC are unknown owing to the heterogeneous composition and intrinsically dynamic nature of the complex. Here, we isolate human PLC from Burkitt's lymphoma cells using an engineered viral inhibitor as bait and determine the structure of native PLC by electron cryo-microscopy. Two endoplasmic reticulum-resident editing modules composed of tapasin, calreticulin, ERp57, and MHC-I are centred around TAP in a pseudo-symmetric orientation. A multivalent chaperone network within and across the editing modules establishes the proofreading function at two lateral binding platforms for MHC-I molecules. The lectin-like domain of calreticulin senses the MHC-I glycan, whereas the P domain reaches over the MHC-I peptide-binding pocket towards ERp57. This arrangement allows tapasin to facilitate peptide editing by clamping MHC-I. The translocation pathway of TAP opens out into a large endoplasmic reticulum lumenal cavity, confined by the membrane entry points of tapasin and MHC-I. Two lateral windows channel the antigenic peptides to MHC-I. Structures of PLC captured at distinct assembly states provide mechanistic insight into the recruitment and release of MHC-I. Our work defines the molecular symbiosis of an ABC transporter and an endoplasmic reticulum chaperone network in MHC-I assembly and provides insight into the onset of the adaptive immune response.


    Organizational Affiliation

    Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Strasse 9, 60438 Frankfurt/Main, Germany.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Beta-2-microglobulinB99Homo sapiensMutation(s): 0 
Gene Names: B2MCDABP0092HDCMA22P
Find proteins for P61769 (Homo sapiens)
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PHAROS  P61769
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
TapasinC428Homo sapiensMutation(s): 0 
Gene Names: TAPBPNGS17TAPA
Find proteins for O15533 (Homo sapiens)
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PHAROS  O15533
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  • Reference Sequence
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Protein disulfide-isomerase A3D481Homo sapiensMutation(s): 0 
Gene Names: PDIA3ERP57ERP60GRP58
EC: 5.3.4.1
Find proteins for P30101 (Homo sapiens)
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PHAROS  P30101
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  • Reference Sequence
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Entity ID: 4
MoleculeChainsSequence LengthOrganismDetailsImage
HLA class I histocompatibility antigen, A-3 alpha chainF341Homo sapiensMutation(s): 0 
Gene Names: HLA-AHLAA
Find proteins for P04439 (Homo sapiens)
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PHAROS  P04439
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  • Reference Sequence
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Entity ID: 5
MoleculeChainsSequence LengthOrganismDetailsImage
CalreticulinG400Homo sapiensMutation(s): 0 
Gene Names: CALRCRTC
Find proteins for P27797 (Homo sapiens)
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PHAROS  P27797
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  • Reference Sequence
Oligosaccharides

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Entity ID: 6
MoleculeChainsChain Length2D Diagram Glycosylation3D Interactions
2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose
A
2 N/A Oligosaccharides Interaction
Entity ID: 7
MoleculeChainsChain Length2D Diagram Glycosylation3D Interactions
beta-D-glucopyranose-(1-3)-alpha-D-mannopyranose-(1-2)-alpha-D-mannopyranose-(1-2)-alpha-D-mannopyranose
E
4 N/A Oligosaccharides Interaction
Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Resolution: 5.80 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
German Research FoundationGermanySFB 807
German Research FoundationGermanyGRK 1986

Revision History 

  • Version 1.0: 2017-11-29
    Type: Initial release
  • Version 1.1: 2017-12-06
    Changes: Database references
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Atomic model, Data collection, Derived calculations, Structure summary