Comparison of proposed putative active conformations of myelin basic protein epitope 87-99 linear altered peptide ligands by spectroscopic and modelling studies: the role of positions 91 and 96 in T-cell receptor activation

J Med Chem. 2006 Nov 16;49(23):6683-91. doi: 10.1021/jm060040z.

Abstract

This work proposes a structural motif for the inhibition of experimental autoimmune encephalomyelitis (EAE) by the linear altered peptide ligands (APLs) [Ala91,96] MBP87-99 and [Arg91,Ala96] MBP87-99 of myelin basic protein. Molecular dynamics was applied to reveal distinct populations of EAE antagonist [Ala91,96] MBP87-99 in solution, in agreement with NOE data. The combination of the theoretical and experimental results led to the identification of a putative active conformation. This approach is of value as no crystallographic data is available for the APL-receptor complex. TCR contact residue Phe89 has an altered topology in the putative bioactive conformations of both APLs with respect to the native peptide, as found via crystallography; it is no longer prominent and solvent exposed. It is proposed that the antagonistic activity of the APLs is due to their binding to MHC, preventing the binding of self-myelin epitopes, with the absence of an immunologic response as the loss of some interactions with the TCR hinders activation of T-cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Epitopes
  • Ligands
  • Magnetic Resonance Spectroscopy
  • Models, Molecular*
  • Molecular Conformation
  • Myelin Basic Protein / chemistry*
  • Peptide Fragments / chemistry*
  • Receptors, Antigen, T-Cell / agonists*
  • Solutions
  • Structure-Activity Relationship
  • Thermodynamics

Substances

  • Epitopes
  • Ligands
  • Myelin Basic Protein
  • Peptide Fragments
  • Receptors, Antigen, T-Cell
  • Solutions
  • myelin basic protein (87-99), Ala(91,96)-
  • myelin basic protein (87-99), Arg(91)-Ala(96)-