Kinetic evidence for a ligand-binding-induced conformational transition in the T cell receptor
- Dmitry M. Gakamsky†,‡,
- Erwin Lewitzki§,
- Ernst Grell§,
- Xavier Saulquin¶,
- Bernard Malissen‖,
- Felix Montero-Julian††,
- Marc Bonneville¶,††, and
- Israel Pecht†,‡‡
- †Department of Immunology, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel;
- §Max Planck Institute of Biophysics, 60596 Frankfurt, Germany;
- ¶Institut National de la Santé et de la Recherche Médicale, U601, 44093 Nantes, France;
- ‖Centre d'Immunologie de Marseille-Luminy, Université de la Méditerranée, Institut National de la Santé et de la Recherche Médicale, U631, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, F-13288 Marseille Cedex 9, France; and
- ††Immunotech-Beckman Coulter, F-13276 Marseille Cedex 9, France
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Communicated by Michael Sela, Weizmann Institute of Science, Rehovot, Israel, August 7, 2007 (received for review May 10, 2007)
Abstract
Thermodynamics and kinetics of the interaction between T cell receptor specific for cytomegalovirus peptide (TCRCMV) and its specific ligand, pp65–HLA-A*0201 complex, were studied by surface plasmon resonance and stopped-flow methods. In the latter measurements, fluorescence resonance energy transfer (FRET) between fluorescently labeled reactants was used. Thermodynamic data derived from surface plasmon resonance measurements suggest that the complex formation is driven by both favorable enthalpy and entropy. Two reaction phases were resolved by the stopped-flow measurements. The rate constant of the first step was calculated to be close to the diffusion-controlled limit rate (3·105 to 106 M−1·s−1), whereas the second step's reaction rate was found to be concentration independent and relatively slow (2–4 s−1 at 25°C). These findings strongly suggest that the interactions between the TCR and its ligand, the peptide–MHC complex, proceed by a two-step mechanism, in which the second step is an induced-fit process, rate determining for antigen recognition by TCR.
Footnotes
- ‡‡To whom correspondence should be addressed. E-mail: israel.pecht{at}weizmann.ac.il
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Author contributions: D.M.G. and I.P. designed research; D.M.G., E.L., and E.G. performed research; X.S., B.M., F.M.-J., and M.B. contributed new reagents/analytic tools; D.M.G., E.L., and E.G. analyzed data; and D.M.G., E.L., E.G., B.M., and I.P. wrote the paper.
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↵ ‡Present address: Edinburgh Instruments Ltd., 2 Bain Square, Kirkton Campus, Livingston EH54 7DQ, United Kingdom.
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The authors declare no conflict of interest.
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See Commentary on page 16398.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0707061104/DC1.
- Abbreviations:
- SPR,
- surface plasmon resonance;
- pMHC,
- peptide–MHC complex;
- TCR,
- T cell receptor;
- CDR,
- complementarity determining region;
- TMR,
- tetramethylrhodamine;
- β2m,
- β2-microglobulin;
- TCRCMV,
- TCR specific for cytomegalovirus peptide.
- © 2007 by The National Academy of Sciences of the USA
