'''Structure of a microbial glycosphingolipid bound to mouse CD1d'''
===Structure of a microbial glycosphingolipid bound to mouse CD1d===
==Overview==
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Natural killer T (NKT) cells provide an innate-type immune response upon T cell receptor interaction with CD1d-presented antigens. We demonstrate through equilibrium tetramer binding and antigen presentation assays with Valpha14i-positive NKT cell hybridomas that the Sphingomonas glycolipid alpha-galacturonosyl ceramide (GalA-GSL) is a NKT cell agonist that is significantly weaker than alpha-galactosylceramide (alpha-GalCer), the most potent known NKT agonist. For GalA-GSL, a shorter fatty acyl chain, an absence of the 4-OH on the sphingosine tail and a 6'-COOH group on the galactose moiety account for its observed antigenic potency. We further determined the crystal structure of mCD1d in complex with GalA-GSL at 1.8-A resolution. The overall binding mode of GalA-GSL to mCD1d is similar to that of the short-chain alpha-GalCer ligand PBS-25, but its sphinganine chain is more deeply inserted into the F' pocket due to alternate hydrogen-bonding interactions between the sphinganine 3-OH with Asp-80. Subsequently, a slight lateral shift (>1 A) of the galacturonosyl head group is noted at the CD1 surface compared with the galactose of alpha-GalCer. Because the relatively short C(14) fatty acid of GalA-GSL does not fully occupy the A' pocket, a spacer lipid is found that stabilizes this pocket. The lipid spacer was identified by GC/MS as a mixture of saturated and monounsaturated palmitic acid (C(16)). Comparison of available crystal structures of alpha-anomeric glycosphingolipids now sheds light on the structural basis of their differential antigenic potency and has led to the design and synthesis of NKT cell agonists with enhanced cell-based stimulatory activities compared with alpha-GalCer.
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==About this Structure==
==About this Structure==
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[[Category: Nkt cell]]
[[Category: Nkt cell]]
[[Category: Tcr]]
[[Category: Tcr]]
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Revision as of 11:30, 29 July 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
2FIK is a Protein complex structure of sequences from Mus musculus. Full crystallographic information is available from OCA.
Reference
Design of natural killer T cell activators: structure and function of a microbial glycosphingolipid bound to mouse CD1d., Wu D, Zajonc DM, Fujio M, Sullivan BA, Kinjo Y, Kronenberg M, Wilson IA, Wong CH, Proc Natl Acad Sci U S A. 2006 Mar 14;103(11):3972-7. Epub 2006 Mar 6. PMID:16537470
