International Immunology, Vol 10, 1753-1764, Copyright © 1998 by Oxford University Press
P Weber, I Raynaud, L Ettouati, MC Trescol-Biemont, PA Carrupt, J Paris, C Rabourdin-Combe, D Gerlier and B Testa
A bound conformation of the antigenic decapeptide hen egg lysozyme
HEL[52-61] associated to the mouse MHC class II (MHC II) I-Ak was modeled
by homology with the three-dimensional structure of hemagglutinin
HA[306-318]-HLA-DR1 complex. HEL peptide Tyr53 could not be aligned with
the HA peptide Tyr308 because this resulted in a buried Tyr53 side chain
within the I-Ak peptide-binding groove and this conflicted with this side
chain being recognized by T cells. Therefore, Asp52 of HEL was fixed as the
P1 anchor and aligned on Tyr308 of HA. After molecular dynamics, the
modeled complex was stable even in the absence of any constraint. The
peptide backbone adopted a polyproline II-like conformation with canonical
hydrogen bonding between the peptide backbone and MHC II molecule. Asp52,
IIe55, Gin57 and Ser60 were predicted to be deeply buried into P1, P4, P6
and P9 MHC II pockets, and Tyr53, Leu56, Asn59 and Arg61 as TCR contacting
residues. The modeling of 15 complexes associating I-Ak with peptides
derived from HEL[52-61] by single amino acid substitution proved stable
with conserved hydrogen bonds and side chain orientation compatible with
their recognition by two T cell hybridomas. Moreover, comparison with the
recently solved crystal structure of the related HEL[50-62]-I-Ak complex
revealed striking similarities.
ARTICLES
Molecular modeling of hen egg lysozyme HEL[52-61] peptide binding to I- Ak MHC class II molecule
Institut de Chimie Therapeutique, Ecole de Pharmacie, Universite de Lausanne, Switzerland.
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