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Natural T cell epitope containing methyl lysines on mycobacterial heparin-binding hemagglutinin

par Corbiere, Véronique ;Segers, Jérôme;Desmet, Rémi;Lecher, Sophie;Loyens, Marc;Petit, Emmanuelle;Melnyk, Oleg;Locht, Camille ;Mascart, Françoise
Référence The Journal of immunology, 204, 7, page (1715-1723)
Publication Publié, 2020-04-01

Article révisé par les pairs

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Résumé :

T cell epitopes are mostly nonmodified peptides, although posttranslationally modified peptide epitopes have been described, but they originated from viral or self-proteins. In this study, we provide evidence of a bacterial methylated T cell peptide epitope. The mycobacterial heparin-binding hemagglutinin (HBHA) is a protein Ag with a complex C-terminal methylation pattern and is recognized by T cells from humans latently infected with Mycobacterium tuberculosis. By comparing native HBHAwith recombinant HBHA produced in Mycobacterium smegmatis (rHBHA-Ms), we could link antigenic differences to differences in the methylation profile. Peptide scan analyses led to the discovery of a peptide containing methyl lysines recognized by a mAb that binds to native HBHA ∼100-fold better than to rHBHA-Ms. This peptide was also recognized by T cells from latently infected humans, as evidenced by IFN-g release upon peptide stimulation. The nonmethylated peptide did not induce IFN-g, arguing that the methyl lysines are part of the T cell epitope.