Structure of a single-chain Fv bound to the 17 N-terminal amino acids of huntingtin provides insights into pathogenic amyloid formation and suppression
De Genst, Erwin
Chirgadze, Dimitri Y.
Klein, Fabrice A. C.
Butler, David C.
Huston, James S.
Dobson, Christopher M.
Journal of Molecular Biology
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De Genst, E., Chirgadze, D. Y., Klein, F. A. C., Butler, D. C., Matak-Vinković, D., Trottier, Y., Huston, J. S., et al. (2015). Structure of a single-chain Fv bound to the 17 N-terminal amino acids of huntingtin provides insights into pathogenic amyloid formation and suppression. Journal of Molecular Biology, 427 (12), 2166-2178. https://doi.org/10.1016/j.jmb.2015.03.021
This is the final published version. It first appeared at http://www.sciencedirect.com/science/article/pii/S002228361500217X#.
Huntington's disease is triggered by misfolding of fragments of mutant forms of the huntingtin protein (mHTT) with aberrant polyglutamine expansions. The C4 single-chain Fv antibody (scFv) binds to the first 17 residues of huntingtin [HTT(1-17)] and generates substantial protection against multiple phenotypic pathologies in situ and in vivo. We show in this paper that C4 scFv inhibits amyloid formation by exon1 fragments of huntingtin in vitro and elucidate the structural basis for this inhibition and protection by determining the crystal structure of the complex of C4 scFv and HTT(1-17). The peptide binds with residues 3–11 forming an amphipathic helix that makes contact with the antibody fragment in such a way that the hydrophobic face of this helix is shielded from the solvent. Residues 12–17 of the peptide are in an extended conformation and interact with the same region of another C4 scFv:HTT(1-17) complex in the asymmetric unit, resulting in a β-sheet interface within a dimeric C4 scFv:HTT(1-17) complex. The nature of this scFv–peptide complex was further explored in solution by high-resolution NMR and physicochemical analysis of species in solution. The results provide insights into the manner in which C4 scFv inhibits the aggregation of HTT, and hence into its therapeutic potential, and suggests a structural basis for the initial interactions that underlie the formation of disease-associated amyloid fibrils by HTT.
Huntington’s disease, aggregation inhibition, amyloid, prefibrillar intermediates, single-chain Fv antibody
E.D.G. and C.M.D. are grateful for support by the Medical Research Council (G1002272). We also thank the Hereditary Disease Foundation (A.M.). D.Y.C. is supported by the Crystallographic X-ray Facility at the Department of Biochemistry, University of Cambridge. We would like to acknowledge Dr. Katherine Stott at the Biophysics Facility at the Department of Biochemistry, University of Cambridge, for her help with the ultracentrifugation experiments and Prof. Weiss and Dr. Desplancq at the Ecole Supérieure de Biotechnologie de Strasbourg for the kind gift of the gankyrin-specific scFv, scFvR19 as a control for our in vitro aggregation experiments.
External DOI: https://doi.org/10.1016/j.jmb.2015.03.021
This record's URL: http://www.repository.cam.ac.uk/handle/1810/248020
Attribution 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by/2.0/uk/
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