Effects of the known pathogenic mutations on the aggregation pathway of the amyloidogenic peptide of apolipoprotein A-I

Sara Raimondi, Fulvio Guglielmi, Sofia Giorgetti, Sonia Di Gaetano, Angela Arciello, Daria M. Monti, Annalisa Relini, Daniela Nichino, Silvia M. Doglia, Antonino Natalello, Piero Pucci, Palma Mangione, Laura Obici, Giampaolo Merlini, Monica Stoppini, Paul Robustelli, Gian Gaetano Tartaglia, Michele Vendruscolo, Christopher M. Dobson, Renata PiccoliVittorio Bellotti

Research output: Contribution to journalArticle

Abstract

The 93-residue N-terminal fragment of apolipoprotein A-I (ApoA-I) is the major constituent of fibrils isolated from patients affected by the amyloidosis caused by ApoA-I mutations. We have prepared eight polypeptides corresponding to all the currently known amyloidogenic variants of the N-terminal region of ApoA-I, other than a truncation mutation, and investigated their aggregation kinetics and the associated structural modifications. All the variants adopted a monomeric highly disordered structure in solution at neutral pH, whereas acidification of the solution induced an unstable α-helical conformation and the subsequent aggregation into the cross-β structure aggregate. Two mutations (Δ70-72 and L90P) almost abrogated the lag phase of the aggregation process, three mutations (Δ60-71, L75P, and W50R) significantly accelerated the aggregation rate by 2- to 3-fold, while the remaining three variants (L64P, L60R, and G26R) were not significantly different from the wild type. Therefore, an increase in aggregation propensity cannot explain per se the mechanism of the disease for all the variants. Prediction of the protection factors for hydrogen exchange in the native state of full-length protein reveals, in almost all the variants, an expansion of the conformational fluctuations that could favour the proteolytic cleavage and the release of the amyloidogenic peptide. Such an event seems to be a necessary prerequisite for ApoA-I fibrillogenesis in vivo, but the observed increased aggregation propensity of certain variants can have a strong influence on the severity of the disease, such as an earlier onset and a faster progression.

Original languageEnglish
Pages (from-to)465-476
Number of pages12
JournalJournal of Molecular Biology
Volume407
Issue number3
DOIs
Publication statusPublished - Apr 1 2011

Keywords

  • 1-93 region of apolipoprotein A-I
  • [1-93]ApoA-I
  • AFM
  • ApoA-I
  • apolipoprotein A-I
  • atomic force microscopy
  • ATR
  • attenuated total reflection
  • CD
  • circular dichroism
  • Fourier transform infrared spectroscopy
  • FTIR
  • glutathione S-transferase
  • GST
  • mass spectrometry
  • MS

ASJC Scopus subject areas

  • Molecular Biology

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  • Cite this

    Raimondi, S., Guglielmi, F., Giorgetti, S., Gaetano, S. D., Arciello, A., Monti, D. M., Relini, A., Nichino, D., Doglia, S. M., Natalello, A., Pucci, P., Mangione, P., Obici, L., Merlini, G., Stoppini, M., Robustelli, P., Tartaglia, G. G., Vendruscolo, M., Dobson, C. M., ... Bellotti, V. (2011). Effects of the known pathogenic mutations on the aggregation pathway of the amyloidogenic peptide of apolipoprotein A-I. Journal of Molecular Biology, 407(3), 465-476. https://doi.org/10.1016/j.jmb.2011.01.044