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Updated: Sep 23, 2026
Characterization of Glycoproteins with the Immunoglobulin Fold by X-Ray Crystallography and Biophysical Techniques
Published on: July 5, 2018
Crystal structure of CD1a in complex with a sulfatide self antigen at a resolution of 2.15 A
Dirk M Zajonc1, Marc A Elsliger, Luc Teyton
1Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Insights
This study reveals the structure of human CD1a bound to a sulfatide antigen. The CD1a molecule
Area of Science:
- Immunology
- Structural Biology
- Biochemistry
Background:
- CD1 proteins present lipid antigens to T cells, playing a role in immune responses.
- Understanding CD1-antigen interactions is crucial for deciphering T cell recognition of lipids.
Purpose of the Study:
- To determine the high-resolution crystal structure of human CD1a in complex with a sulfatide antigen.
- To elucidate the molecular details of how CD1a binds and presents lipid antigens.
Main Methods:
- X-ray crystallography
- Protein purification
- X-ray diffraction data collection and analysis
Main Results:
- The crystal structure of human CD1a complexed with a sulfatide was determined at 2.15 A resolution.
- The sulfatide antigen adopted an S-shaped conformation within the CD1a binding site.
- Specific interactions were observed between the lipid's headgroup and the CD1a molecule, facilitating T cell receptor recognition.
- The A' pocket of CD1a acts as a molecular ruler, selecting lipid antigens based on alkyl chain length.
Conclusions:
- The determined structure provides atomic-level insights into CD1a-lipid antigen presentation.
- This structural information is vital for understanding the specificity of CD1-restricted T cell responses.
- The findings contribute to the broader knowledge of antigen presentation by the CD1 family.
Abstract:
CD1 antigens bind a variety of self and foreign lipid and glycolipid antigens for presentation to CD1-restricted T cell receptors (TCRs). Here we report the crystal structure of human CD1a in complex with a sulfatide self antigen at a resolution of 2.15 A. The lipid adopts an S-shaped conformation, with the sphingosine chain completely buried in the A' pocket and the fatty acid chain emerging from the interface of the A' pocket into the more exposed F' pocket. The headgroup is anchored in the A'-F' junction and protrudes into the F' pocket for TCR recognition. Because the A' pocket is narrow with a fixed terminus, it can act as a molecular 'ruler' to select alkyl chains of a particular length.
