title: Synthesis of pathological and nonpathological human exon 1 huntingtin.
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.
authors.affiliation: Institute of Bioanalytical Chemistry, Center for Biotechnology and Biomedicine, Leipzig University, Leipzig, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Singer
authors.forename: Thomas
authors.initials: T
authors.lastname: Zauner
authors.forename: Maika
authors.initials: M
authors.lastname: Genz
authors.forename: Ralf
authors.initials: R
authors.lastname: Hoffmann
authors.forename: Thole
authors.initials: T
authors.lastname: Zuchner
mesh_terms: D005091:Exons; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000138:chemical synthesis* / Q000737:chemistry / Q000235:genetics*; D009687:Nuclear Proteins / Q000138:chemical synthesis* / Q000737:chemistry / Q000235:genetics*; D010455:Peptides; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; C097188:polyglutamine