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PDBsum entry 2icw
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Immune system
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PDB id
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2icw
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Contents |
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179 a.a.
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184 a.a.
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13 a.a.
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213 a.a.
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110 a.a.
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113 a.a.
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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 structure of a complete ternary complex of tcr, Superantigen and peptide-Mhc.
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Authors
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L.Wang,
Y.Zhao,
Z.Li,
Y.Guo,
L.L.Jones,
D.M.Kranz,
W.Mourad,
H.Li.
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Ref.
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Nat Struct Mol Biol, 2007,
14,
169-171.
[DOI no: ]
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PubMed id
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Abstract
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'Superantigens' (SAgs) trigger the massive activation of T cells by simultaneous
interactions with MHC and TCR receptors, leading to human diseases. Here we
present the first crystal structure, at 2.5-A resolution, of a complete ternary
complex between a SAg and its two receptors, HLA-DR1/HA and TCR. The most
striking finding is that the SAg Mycoplasma arthritidis mitogen, unlike others,
has direct contacts not only with TCR Vbeta but with TCR Valpha.
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Figure 1.
Figure 1. Crystal structure of scTCR–MAM–HLA-DR1/HA ternary
complex. Lime, MAM; blue, DR1  ;
cyan, DR1  ;
red, HA; purple, TCR V ;
green, TCR V .
(a) Structure of the scTCR–MAM–HLA-DR1/HA complex. (b)
Interaction surfaces of MAM and scTCR T7. Center, surface
presentation of the MAM–scTCR structure; left, opened-up view
of the MAM-binding surface of scTCR; right, opened-up view of
the TCR-binding surface of MAM. Hydrophobic surface patches are
colored in cyan. CDR and HV4 loops of TCR are shown as 'worms'.
Selected aromatic residues of TCR at the interface are shown as
rods. (c) Sequence alignment of the V residues
of MAM-reactive (indicated by +) and unreactive (-) TCRs.
Conserved or conservatively substituted residues (red boxes) and
MAM-contacting residues (red asterisks) are indicated. (d)
Sequence alignment of MAM-contacting residues of TCR V s
that are most frequently activated by MAM (indicated by +) and
TCR V s
that are less frequently activated by MAM. Conserved residues
indicated as in c; green boxes mark strictly conserved cysteine
residues.
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Figure 2.
Figure 2. Conformational changes in MAM and TCR upon complex
formation. (a) Superposition of the MAM–HLA-DR1/HA complex
(green) determined in our earlier study^13 onto its counterpart
(red) in the ternary complex. The MAM CTD is not included in
superposition. (b) Superposition of the MAM CTD in the previous
MAM–HLA-DR1/HA binary complex^13 onto its counterpart (red) in
the ternary complex. (c) Superposition of the ligand-free TCR-2C
(ref. 2), and TCR-2C in complexes with H-2K^b MHC I with an
agonist^14 and a superagonist peptide^15, onto TCR T7 in our
ternary complex. Light gray, non-CDR regions; purple, CDRs of V
;
green, T7 V ;
lime, free 2C; pink, 2C with agonist peptide; cyan, 2C with
superagonist peptide.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Mol Biol
(2007,
14,
169-171)
copyright 2007.
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