Solution NMR structure of an immunodominant epitope of myelin basic protein: Conformational dependence on environment of an intrinsically unstructured protein

Christophe Farès, David S. Libich, George Harauz

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

Using solution NMR spectroscopy, three-dimensional structures have been obtained for an 18-residue synthetic polypeptide fragment of 18.5 kDa myelin basic protein (MBP, human residues Q81-T98) under three conditions emulating the protein's natural environment in the myelin membrane to varying degrees: (a) an aqueous solution (100 mm KCl pH 6.5), (b) a mixture of trifluoroethanol (TFE-d2) and water (30:70% v/v), and (c) a dispersion of 100 mm dodecylphosphocholine (DPC-d38, 1:100 protein/lipid molar ratio) micelles. This polypeptide sequence is highly conserved in MBP from mammals, amphibians, and birds, and comprises a major immunodominant epitope (human residues N83-T92) in the autoimmune disease multiple sclerosis. In the polypeptide fragment, this epitope forms a stable, amphipathic, α helix under organic and membrane-mimetic conditions, but has only a partially helical conformation in aqueous solution. These results are consistent with recent molecular dynamics simulations that showed this segment to have a propensity to form a transient α helix in aqueous solution, and with electron paramagnetic resonance (EPR) experiments that suggested a α-helical structure when bound to a membrane [I. R. Bates, J. B. Feix, J. M. Boggs & G. Harauz (2004) J Biol Chem, 279, 5757-5764]. The high sensitivity of the epitope structure to its environment is characteristic of intrinsically unstructured proteins, like MBP, and reflects its association with diverse ligands such as lipids and other proteins.

Original languageEnglish (US)
Pages (from-to)601-614
Number of pages14
JournalFEBS Journal
Volume273
Issue number3
DOIs
StatePublished - Feb 2006
Externally publishedYes

Keywords

  • Correlation spectroscopy
  • Immunodominant epitope
  • Multiple sclerosis
  • Myelin basic protein
  • Solution NMR

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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