American Association for Cancer Research
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Supplementary Figure 2 from Design of Agonistic Altered Peptides for the Robust Induction of CTL Directed towards H-2Db in Complex with the Melanoma-Associated Epitope gp100

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posted on 2023-03-30, 19:20 authored by Marianne J.B. van Stipdonk, Daniel Badia-Martinez, Marjolein Sluijter, Rienk Offringa, Thorbald van Hall, Adnane Achour
Supplementary Figure 2 from Design of Agonistic Altered Peptides for the Robust Induction of CTL Directed towards H-2Db in Complex with the Melanoma-Associated Epitope gp100

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ARTICLE ABSTRACT

Immunogenicity of tumor-associated antigens (TAA) is often weak because many TAA are autoantigens for which the T-cell repertoire is sculpted by tolerance mechanisms. Substitutions at main anchor positions to increase the complementarity between the peptide and the MHC class I (MHC-I) binding cleft constitute a common procedure to improve binding capacity and immunogenicity of TAA. However, such alterations are tailored for each MHC-I allele and may recruit different CTL specificities through conformational changes in the targeted peptides. Comparative analysis of substituted melanoma-differentiation antigen gp100 in complex with H-2Db revealed that combined introduction of glycine and proline residues at the nonanchor positions 2 and 3, respectively, resulted in an agonistic altered peptide with dramatically enhanced binding affinity, stability, and immunogenicity of this TAA. Peptide vaccination using the p2Gp3P-altered peptide version of gp100 induced high frequencies of melanoma-specific CTL in the endogenous CD8+ repertoire. Crystal structure analysis of MHC/peptide complexes revealed that the conformation of the modified p2Gp3P-peptide was similar to the wild-type peptide, and indicated that this mimotope was stabilized through interactions between peptide residue p3P and the tyrosine residue Y159 that is conserved among most known MHC-I molecules throughout mammalian species. Our results may provide an alternative approach to enhance MHC stabilization capacity and immunogenicity of low-affinity peptides for induction of robust tumor-specific CTL. [Cancer Res 2009;69(19):7784–92]