<p>KRAS G12 mutations are frequent oncogenic drivers, yet their differential immunogenicity complicates T cell-based therapies. Here, we integrate structural, biophysical, and functional analyses to examine how KRAS G12 variants remodel peptide-MHC-I (pMHC) architecture and T cell receptor (TCR) recognition. Using HLA-A*11:01, we show that single residue substitutions at position 12 induce distinct conformational changes in the MHC groove, with G12D uniquely destabilizing the complex through a buried aspartate side chain. Notably, G12D peptides adopt two registers, a 9-mer and a 10-mer, that diverge sharply in structure and immunogenicity. The 10-mer forms a compact, stable pMHC with a TCR-accessible surface, while the 9-mer adopts a bent conformation incompatible with recognition. Molecular dynamics and NMR titration confirm the superior stability and binding affinity of the 10-mer. These results highlight how peptide length and conformation critically shape immune visibility, offering mechanistic insight for optimizing TCR-T therapies against elusive neoantigens like KRAS G12D.</p>

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Structure guided analysis of KRAS G12 mutants in HLA-A*11:01 reveals a length encoded immunogenic advantage in G12D

  • Jiali Zhu,
  • Zhifeng Chen,
  • Xi Xu,
  • Yuxuan Wang,
  • Pei Liu,
  • Maorong Wen,
  • Quanmeng Wang,
  • Yuchen He,
  • Hongwei Jin,
  • Hongjuan Xue,
  • Shuqing Wang,
  • Ke Xu,
  • Linlin Zhao

摘要

KRAS G12 mutations are frequent oncogenic drivers, yet their differential immunogenicity complicates T cell-based therapies. Here, we integrate structural, biophysical, and functional analyses to examine how KRAS G12 variants remodel peptide-MHC-I (pMHC) architecture and T cell receptor (TCR) recognition. Using HLA-A*11:01, we show that single residue substitutions at position 12 induce distinct conformational changes in the MHC groove, with G12D uniquely destabilizing the complex through a buried aspartate side chain. Notably, G12D peptides adopt two registers, a 9-mer and a 10-mer, that diverge sharply in structure and immunogenicity. The 10-mer forms a compact, stable pMHC with a TCR-accessible surface, while the 9-mer adopts a bent conformation incompatible with recognition. Molecular dynamics and NMR titration confirm the superior stability and binding affinity of the 10-mer. These results highlight how peptide length and conformation critically shape immune visibility, offering mechanistic insight for optimizing TCR-T therapies against elusive neoantigens like KRAS G12D.