Synthesis of pathological and nonpathological human exon 1 huntingtin

J Pept Sci. 2010 Jul;16(7):358-63. doi: 10.1002/psc.1252.

Abstract

Huntington's disease (HD) is a neurodegenerative disorder that affects approximately 1 in 10 000 individuals. The underlying gene mutation was identified as a CAG-triplet repeat expansion in the gene huntingtin. The CAG sequence codes for glutamine, and in HD, an expansion of the polyglutamine (poly-Q) stretch above 35 glutamine residues results in pathogenicity. It has been demonstrated in various animal models that only the expression of exon 1 huntingtin, a 67-amino acid-long polypeptide plus a variable poly-Q stretch, is sufficient to cause full HD-like pathology. Therefore, a deeper understanding of exon 1 huntingtin, its structure, aggregation mechanism and interaction with other proteins is crucial for a better understanding of the disease. Here, we describe the synthesis of a 109-amino acid-long exon 1 huntingtin peptide including a poly-Q stretch of 42 glutamines. This microwave-assisted solid phase peptide synthesis resulted in milligram amounts of peptide with high purity. We also synthesized a nonpathogenic version of exon 1 huntingtin (90-amino acid long including a poly-Q stretch of 23 glutamine residues) using the same strategy. In circular dichroism spectroscopy, both polypeptides showed weak alpha-helical properties with the longer peptide showing a higher helical degree. These model peptides have great potential for further biomedical analyses, e.g. for large-scale pre-screenings for aggregation inhibitors, further structural analyses as well as protein-protein interaction studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Exons
  • Humans
  • Huntingtin Protein
  • Huntington Disease / genetics
  • Nerve Tissue Proteins / chemical synthesis*
  • Nerve Tissue Proteins / chemistry
  • Nerve Tissue Proteins / genetics*
  • Nuclear Proteins / chemical synthesis*
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics*
  • Peptides
  • Protein Structure, Secondary
  • Structure-Activity Relationship

Substances

  • HTT protein, human
  • Huntingtin Protein
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • Peptides
  • polyglutamine