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PDBsum entry 4f7c
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Immune system
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PDB id
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4f7c
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References listed in PDB file
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Key reference
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Title
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Crystal structures of bovine cd1d reveal altered αgalcer presentation and a restricted a' Pocket unable to bind long-Chain glycolipids.
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Authors
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J.Wang,
J.Guillaume,
N.Pauwels,
S.Van calenbergh,
I.Van rhijn,
D.M.Zajonc.
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Ref.
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Plos One, 2012,
7,
e47989.
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PubMed id
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Abstract
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NKT cells play important roles in immune surveillance. They rapidly respond to
pathogens by detecting microbial glycolipids when presented by the non-classical
MHC I homolog CD1d. Previously, ruminants were considered to lack NKT cells due
to the lack of a functional CD1D gene. However, recent data suggest that cattle
express CD1d with unknown function. In an attempt to characterize the function
of bovine CD1d, we assessed the lipid binding properties of recombinant Bos
taurus CD1d (boCD1d) in vitro. BoCD1d is able to bind glycosphingolipids (GSLs)
with fatty acid chain lengths of C(18), while GSLs with fatty acids of C(24) do
not bind. Crystal structures of boCD1d bound to a short-chain C(12)-di-sulfatide
antigen, as well as short-chain C(16)-αGalCer revealed that the Á pocket of
boCD1d is restricted in size compared to that of both mouse and human CD1d,
explaining the inability of long chain GSL's to bind to boCD1d. Moreover, while
di-sulfatide is presented similarly compared to the presentation of sulfatide by
mouse CD1d, αGalCer is presented differently at the cell surface, due to an
amino acid Asp151Asn substitution that results in loss of intimate contacts
between the αGalCer headgroup and CD1d. The altered αGalCer presentation by
boCD1d also explains its lack of cross-activation of mouse iNKT cells and raises
the interesting question of the nature and function of bovine lipid-reactive T
cells.
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