PDBsum entry 5edx

Immune system

PDB id: 5edx

Contents

Protein chains

114 a.a.

Waters ×302

PDB id:

5edx

Name:

Immune system

Title:

Crystal structure of swine cd8aa homodimer

Structure:

Cd8 alpha antigen. Chain: a, b. Fragment: unp residues 2-115. Engineered: yes

Source:

Sus scrofa. Pig. Organism_taxid: 9823. Gene: cd8a. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.80Å R-factor: 0.184 R-free: 0.209

Authors:

Y.J.Liu,J.X.Qi,N.Z.Zhang,C.Xia

Key ref:

Y.Liu et al. (2016). The structural basis of chicken, swine and bovine CD8αα dimers provides insight into the co-evolution with MHC I in endotherm species. Sci Rep, 6, 24788. PubMed id: 27122108

Date:

22-Oct-15 Release date: 14-Sep-16

Protein chains

A0MNZ3  (A0MNZ3_PIG) -  T-cell surface glycoprotein CD8 alpha chain (Fragment) from Sus scrofa

Seq: 213 a.a.

Struc: 114 a.a.

Sci Rep 6:24788 (2016)

PubMed id: 27122108

The structural basis of chicken, swine and bovine CD8αα dimers provides insight into the co-evolution with MHC I in endotherm species.

Y.Liu, X.Li, J.Qi, N.Zhang, C.Xia.

ABSTRACT

It is unclear how the pivotal molecules of the adaptive immune system (AIS) maintain their inherent characteristics and relationships with their co-receptors over the course of co-evolution. CD8α, a fundamental but simple AIS component with only one immunoglobulin variable (IgV) domain, is a good example with which to explore this question because it can fold correctly to form homodimers (CD8αα) and interact with peptide-MHC I (p/MHC I) with low sequence identities between different species. Hereby, we resolved the crystal structures of chicken, swine and bovine CD8αα. They are typical homodimers consisting of two symmetric IgV domains with distinct species specificities. The CD8αα structures indicated that a few highly conserved residues are important in CD8 dimerization and in interacting with p/MHC I. The dimerization of CD8αα mainly depends on the pivotal residues on the dimer interface; in particular, four aromatic residues provide many intermolecular forces and contact areas. Three residues on the surface of CD8α connecting cavities that formed most of the hydrogen bonds with p/MHC I were also completely conserved. Our data propose that a few key conserved residues are able to ensure the CD8α own structural characteristics despite the great sequence variation that occurs during evolution in endotherms.