1k8d
From Proteopedia
(New page: 200px<br /><applet load="1k8d" size="450" color="white" frame="true" align="right" spinBox="true" caption="1k8d, resolution 2.30Å" /> '''crystal structure of...) |
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| - | [[Image:1k8d.jpg|left|200px]]<br /><applet load="1k8d" size=" | + | [[Image:1k8d.jpg|left|200px]]<br /><applet load="1k8d" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1k8d, resolution 2.30Å" /> | caption="1k8d, resolution 2.30Å" /> | ||
'''crystal structure of the non-classical MHC class Ib Qa-2 complexed with a self peptide'''<br /> | '''crystal structure of the non-classical MHC class Ib Qa-2 complexed with a self peptide'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Qa-2 is a nonclassical MHC Ib antigen, which has been | + | BACKGROUND: Qa-2 is a nonclassical MHC Ib antigen, which has been implicated in both innate and adaptive immune responses, as well as embryonic development. Qa-2 has an unusual peptide binding specificity in that it requires two dominant C-terminal anchor residues and is capable of associating with a substantially more diverse array of peptide sequences than other nonclassical MHC. RESULTS: We have determined the crystal structure, to 2.3 A, of the Q9 gene of murine Qa-2 complexed with a self-peptide derived from the L19 ribosomal protein, which is abundant in the pool of peptides eluted from the Q9 groove. The 9 amino acid peptide is bound high in a shallow, hydrophobic binding groove of Q9, which is missing a C pocket. The peptide makes few specific contacts and exhibits extremely poor shape complementarity to the MHC groove, which facilitates the presentation of a degenerate array of sequences. The L19 peptide is in a centrally bulged conformation that is stabilized by intramolecular interactions from the invariant P7 histidine anchor residue and by a hydrophobic core of preferred secondary anchor residues that have minimal interaction with the MHC. CONCLUSIONS: Unexpectedly, the preferred secondary peptide residues that exhibit tenuous contact with Q9 contribute significantly to the overall stability of the peptide-MHC complex. The structure of this complex implies a "conformational" selection by Q9 for peptide residues that optimally stabilize the large bulge rather than making intimate contact with the MHC pockets. |
==About this Structure== | ==About this Structure== | ||
| - | 1K8D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http:// | + | 1K8D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K8D OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Mus musculus]] | [[Category: Mus musculus]] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
| - | [[Category: Garcia, K | + | [[Category: Garcia, K C.]] |
[[Category: He, X.]] | [[Category: He, X.]] | ||
[[Category: Ho, J.]] | [[Category: Ho, J.]] | ||
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[[Category: qa-2]] | [[Category: qa-2]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:31:11 2008'' |
Revision as of 11:31, 21 February 2008
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crystal structure of the non-classical MHC class Ib Qa-2 complexed with a self peptide
Overview
BACKGROUND: Qa-2 is a nonclassical MHC Ib antigen, which has been implicated in both innate and adaptive immune responses, as well as embryonic development. Qa-2 has an unusual peptide binding specificity in that it requires two dominant C-terminal anchor residues and is capable of associating with a substantially more diverse array of peptide sequences than other nonclassical MHC. RESULTS: We have determined the crystal structure, to 2.3 A, of the Q9 gene of murine Qa-2 complexed with a self-peptide derived from the L19 ribosomal protein, which is abundant in the pool of peptides eluted from the Q9 groove. The 9 amino acid peptide is bound high in a shallow, hydrophobic binding groove of Q9, which is missing a C pocket. The peptide makes few specific contacts and exhibits extremely poor shape complementarity to the MHC groove, which facilitates the presentation of a degenerate array of sequences. The L19 peptide is in a centrally bulged conformation that is stabilized by intramolecular interactions from the invariant P7 histidine anchor residue and by a hydrophobic core of preferred secondary anchor residues that have minimal interaction with the MHC. CONCLUSIONS: Unexpectedly, the preferred secondary peptide residues that exhibit tenuous contact with Q9 contribute significantly to the overall stability of the peptide-MHC complex. The structure of this complex implies a "conformational" selection by Q9 for peptide residues that optimally stabilize the large bulge rather than making intimate contact with the MHC pockets.
About this Structure
1K8D is a Protein complex structure of sequences from Mus musculus. Full crystallographic information is available from OCA.
Reference
Promiscuous antigen presentation by the nonclassical MHC Ib Qa-2 is enabled by a shallow, hydrophobic groove and self-stabilized peptide conformation., He X, Tabaczewski P, Ho J, Stroynowski I, Garcia KC, Structure. 2001 Dec;9(12):1213-24. PMID:11738047
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