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PDBsum entry 5edx
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Immune system
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PDB id
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5edx
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References listed in PDB file
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Key reference
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Title
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The structural basis of chicken, Swine and bovine cd8αα dimers provides insight into the co-Evolution with mhc i in endotherm species.
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Authors
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Y.Liu,
X.Li,
J.Qi,
N.Zhang,
C.Xia.
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Ref.
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Sci Rep, 2016,
6,
24788.
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PubMed id
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Abstract
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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.
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