Structure induction of the T-cell receptor zeta-chain upon lipid binding investigated by NMR spectroscopy.
The conformation of the cytoplasmic part of the zeta-chain of the T-cell receptor (TCR) in its free form and bound to detergent micelles has been investigated by heteronuclear NMR spectroscopy. The zeta-chain is considered to be a mediator between the extracellular antigen and the intracellular signal-transduction cascade leading to T-cell activation. Earlier studies suggested a T-cell activation mechanism that involved a TCR-state-dependent lipid incorporation propensity of the zeta-chain accompanied by a helical folding transition. In order to support this proposed mechanism, standard protein NMR assignment and secondary-structure-elucidation techniques have been applied to the free TCR zeta-chain and to the zeta-chain bound to the detergent LMPG, which forms a micelle, in order to obtain the structural characteristics of this folding transition in a residue-resolved manner. We could assign the resonances of the free zeta-chain at 278 K, and this formed the basis for chemical-shift-perturbation studies to identify lipid binding sites. Our NMR results show that the free TCR zeta-chain is indeed intrinsically unstructured. Regions around the ITAM2 and ITAM3 sequences are involved in a highly dynamic binding of the free zeta-chain to a detergent micelle formed by the acidic lipid LMPG.
Duchardt
Elke
E
Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe University Frankfurt, 60439 Frankfurt, Germany.
Sigalov
Alexander B
AB
Aivazian
Dikran
D
Stern
Lawrence J
LJ
Schwalbe
Harald
H
D000595:Amino Acid Sequence; D008024:Ligands; D008823:Micelles; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011487:Protein Conformation; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry*
D008024:Ligands; D008823:Micelles; D011948:Receptors, Antigen, T-Cell