6ENY

Structure of the human PLC editing module


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Resolution: 5.8 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

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

  • 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

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Beta-2-microglobulin
B
99Homo sapiensMutation(s): 0 
Gene Names: B2M
Find proteins for P61769 (Homo sapiens)
Go to Gene View: B2M
Go to UniProtKB:  P61769
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Tapasin
C
428Homo sapiensMutation(s): 0 
Gene Names: TAPBP (NGS17, TAPA)
Find proteins for O15533 (Homo sapiens)
Go to Gene View: TAPBP
Go to UniProtKB:  O15533
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Protein disulfide-isomerase A3
D
481Homo sapiensMutation(s): 0 
Gene Names: PDIA3 (ERP57, ERP60, GRP58)
EC: 5.3.4.1
Find proteins for P30101 (Homo sapiens)
Go to Gene View: PDIA3
Go to UniProtKB:  P30101
Entity ID: 4
MoleculeChainsSequence LengthOrganismDetails
HLA class I histocompatibility antigen, A-3 alpha chain
F
341Homo sapiensMutation(s): 0 
Gene Names: HLA-A (HLAA)
Find proteins for P04439 (Homo sapiens)
Go to Gene View: HLA-A
Go to UniProtKB:  P04439
Entity ID: 5
MoleculeChainsSequence LengthOrganismDetails
Calreticulin
G
400Homo sapiensMutation(s): 0 
Gene Names: CALR (CRTC)
Find proteins for P27797 (Homo sapiens)
Go to Gene View: CALR
Go to UniProtKB:  P27797
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MAN
Query on MAN

Download SDF File 
Download CCD File 
G
ALPHA-D-MANNOSE
C6 H12 O6
WQZGKKKJIJFFOK-PQMKYFCFSA-N
 Ligand Interaction
BGC
Query on BGC

Download SDF File 
Download CCD File 
G
BETA-D-GLUCOSE
C6 H12 O6
WQZGKKKJIJFFOK-VFUOTHLCSA-N
 Ligand Interaction
NAG
Query on NAG

Download SDF File 
Download CCD File 
F
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Resolution: 5.8 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

Structure Validation

View Full Validation Report or Ramachandran Plots



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
    Type: Database references