Structure-guided stabilization of pathogen-derived peptide-HLA-E complexes using non-natural amino acids conserves...

Area of Science:

• Immunology
• Structural Biology
• Molecular Medicine

Background:

• Human Leukocyte Antigen-E (HLA-E) is a nonpolymorphic MHC class Ib molecule.
• HLA-E presents peptides derived from HLA class Ia leader sequences, delivering inhibitory signals to Natural Killer (NK) cells via CD94/NKG2 receptors.
• While HLA-E can present pathogen-derived peptides to T cells, the structural basis for this antigen surveillance remains unclear.

Purpose of the Study:

• To determine the molecular basis of T cell receptor (TCR) recognition of HLA-E presented peptides.
• To develop a novel method for stabilizing peptide-HLA-E (pHLA-E) complexes for T cell isolation and therapeutic target identification.

Main Methods:

• Co-complex crystal structure determination of TCRs with bacterial (Mycobacterium tuberculosis) and viral (HIV) origin pHLA-E complexes.
• Development of a cysteine-trap method using non-natural amino acid chemistry to stabilize pHLA-E monomers.
• Characterization of stabilized pHLA-E complexes for maintaining native TCR-pHLA-E interface contacts.

Main Results:

• Solved the first crystal structures of TCR-pHLA-E complexes presenting non-canonical peptides from bacterial and viral pathogens.
• Established a novel cysteine-trap strategy to create stable pHLA-E monomers.
• Demonstrated that stabilized pHLA-E monomers maintain native interactions with TCRs.

Conclusions:

• The structural insights provide a foundation for understanding HLA-E mediated antigen surveillance.
• The developed stabilization method facilitates the isolation of antigen-specific T cells.
• This approach holds potential for identifying therapeutic TCRs targeting pathogen-infected cells.