1en2
From Proteopedia
(New page: 200px<br /><applet load="1en2" size="450" color="white" frame="true" align="right" spinBox="true" caption="1en2, resolution 1.4Å" /> '''UDA TETRASACCHARIDE C...) |
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| - | [[Image:1en2.jpg|left|200px]]<br /><applet load="1en2" size=" | + | [[Image:1en2.jpg|left|200px]]<br /><applet load="1en2" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1en2, resolution 1.4Å" /> | caption="1en2, resolution 1.4Å" /> | ||
'''UDA TETRASACCHARIDE COMPLEX. CRYSTAL STRUCTURE OF URTICA DIOICA AGGLUTININ, A SUPERANTIGEN PRESENTED BY MHC MOLECULES OF CLASS I AND CLASS II'''<br /> | '''UDA TETRASACCHARIDE COMPLEX. CRYSTAL STRUCTURE OF URTICA DIOICA AGGLUTININ, A SUPERANTIGEN PRESENTED BY MHC MOLECULES OF CLASS I AND CLASS II'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Urtica dioica agglutinin (UDA), a monomeric lectin extracted | + | BACKGROUND: Urtica dioica agglutinin (UDA), a monomeric lectin extracted from stinging nettle rhizomes, is specific for saccharides containing N-acetylglucosamine (GlcNAc). The lectin behaves as a superantigen for murine T cells, inducing the exclusive proliferation of Vbeta8.3(+) lymphocytes. UDA is unique among known T cell superantigens because it can be presented by major histocompatibility complex (MHC) molecules of both class I and II. RESULTS: The crystal structure of UDA has been determined in the ligand-free state, and in complex with tri-acetylchitotriose and tetra-acetylchitotetraose at 1.66 A, 1.90 A and 1.40 A resolution, respectively. UDA comprises two hevein-like domains, each with a saccharide-binding site. A serine and three aromatic residues at each site form the principal contacts with the ligand. The N-terminal domain binding site can centre on any residue of a chito-oligosaccharide, whereas that of the C-terminal domain is specific for residues at the nonreducing terminus of the ligand. We have shown previously that oligomers of GlcNAc inhibit the superantigenic activity of UDA and that the lectin binds to glycans on the MHC molecule. We show that UDA also binds to glycans on the T cell receptor (TCR). CONCLUSIONS: The presence of two saccharide-binding sites observed in the structure of UDA suggests that its superantigenic properties arise from the simultaneous fixation of glycans on the TCR and MHC molecules of the T cell and antigen-presenting cell, respectively. The well defined spacing between the two binding sites of UDA is probably a key factor in determining the specificity for Vbeta8.3(+) lymphocytes. |
==About this Structure== | ==About this Structure== | ||
| - | 1EN2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Urtica_dioica Urtica dioica]. Full crystallographic information is available from [http:// | + | 1EN2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Urtica_dioica Urtica dioica]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1EN2 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Urtica dioica]] | [[Category: Urtica dioica]] | ||
| - | [[Category: Bentley, G | + | [[Category: Bentley, G A.]] |
[[Category: Boulot, G.]] | [[Category: Boulot, G.]] | ||
| - | [[Category: Damme, E | + | [[Category: Damme, E J.M Van.]] |
| - | [[Category: Peumans, W | + | [[Category: Peumans, W J.]] |
[[Category: Rovira, P.]] | [[Category: Rovira, P.]] | ||
| - | [[Category: Saul, F | + | [[Category: Saul, F A.]] |
[[Category: Truffa-Bachi, P.]] | [[Category: Truffa-Bachi, P.]] | ||
[[Category: hevein domain]] | [[Category: hevein domain]] | ||
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[[Category: uda]] | [[Category: uda]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:29:27 2008'' |
Revision as of 10:29, 21 February 2008
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UDA TETRASACCHARIDE COMPLEX. CRYSTAL STRUCTURE OF URTICA DIOICA AGGLUTININ, A SUPERANTIGEN PRESENTED BY MHC MOLECULES OF CLASS I AND CLASS II
Overview
BACKGROUND: Urtica dioica agglutinin (UDA), a monomeric lectin extracted from stinging nettle rhizomes, is specific for saccharides containing N-acetylglucosamine (GlcNAc). The lectin behaves as a superantigen for murine T cells, inducing the exclusive proliferation of Vbeta8.3(+) lymphocytes. UDA is unique among known T cell superantigens because it can be presented by major histocompatibility complex (MHC) molecules of both class I and II. RESULTS: The crystal structure of UDA has been determined in the ligand-free state, and in complex with tri-acetylchitotriose and tetra-acetylchitotetraose at 1.66 A, 1.90 A and 1.40 A resolution, respectively. UDA comprises two hevein-like domains, each with a saccharide-binding site. A serine and three aromatic residues at each site form the principal contacts with the ligand. The N-terminal domain binding site can centre on any residue of a chito-oligosaccharide, whereas that of the C-terminal domain is specific for residues at the nonreducing terminus of the ligand. We have shown previously that oligomers of GlcNAc inhibit the superantigenic activity of UDA and that the lectin binds to glycans on the MHC molecule. We show that UDA also binds to glycans on the T cell receptor (TCR). CONCLUSIONS: The presence of two saccharide-binding sites observed in the structure of UDA suggests that its superantigenic properties arise from the simultaneous fixation of glycans on the TCR and MHC molecules of the T cell and antigen-presenting cell, respectively. The well defined spacing between the two binding sites of UDA is probably a key factor in determining the specificity for Vbeta8.3(+) lymphocytes.
About this Structure
1EN2 is a Single protein structure of sequence from Urtica dioica. Full crystallographic information is available from OCA.
Reference
Crystal structure of Urtica dioica agglutinin, a superantigen presented by MHC molecules of class I and class II., Saul FA, Rovira P, Boulot G, Damme EJ, Peumans WJ, Truffa-Bachi P, Bentley GA, Structure. 2000 Jun 15;8(6):593-603. PMID:10873861
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