Understanding TR binding to pMHC complexes: how does a TR scan many pMHC complexes yet preferentially bind to one

Area of Science:

• Immunology
• Computational Biology
• Structural Biology

Background:

• T cell receptor (TR) recognition of peptide-MHC (pMHC) complexes is crucial for adaptive immunity.
• Understanding this interaction is key to deciphering immune responses and developing therapies.

Purpose of the Study:

• To analyze TR/pMHC interactions using computational methods.
• To develop a novel approach for calculating TR docking angles and understanding binding specificity.

Main Methods:

• Analysis of 61 TR/pMHC crystallographic structures.
• Computation of binding free energy (BE), TR paratope, pMHC epitope, molecular surface electrostatic potential (MSEP), and TR docking angle (θ).

Main Results:

• A novel, rational method for calculating the TR docking angle (θ) was developed.
• A linear correlation between binding energy (BE) and docking angle (θ) was found, independent of specific amino acids.
• A mechanism for pMHC recognition by TR, leading to T cell activation, was proposed.

Conclusions:

• The peptide component significantly influences TR specificity.
• The findings challenge the "germline bias" theory and offer new insights into TR/pMHC interactions.
• This work provides a framework for understanding how TRs scan and specifically bind pMHC ligands.