TY - JOUR
T1 - Effects of the known pathogenic mutations on the aggregation pathway of the amyloidogenic peptide of apolipoprotein A-I
AU - Raimondi, Sara
AU - Guglielmi, Fulvio
AU - Giorgetti, Sofia
AU - Gaetano, Sonia Di
AU - Arciello, Angela
AU - Monti, Daria M.
AU - Relini, Annalisa
AU - Nichino, Daniela
AU - Doglia, Silvia M.
AU - Natalello, Antonino
AU - Pucci, Piero
AU - Mangione, Palma
AU - Obici, Laura
AU - Merlini, Giampaolo
AU - Stoppini, Monica
AU - Robustelli, Paul
AU - Tartaglia, Gian Gaetano
AU - Vendruscolo, Michele
AU - Dobson, Christopher M.
AU - Piccoli, Renata
AU - Bellotti, Vittorio
PY - 2011/4/1
Y1 - 2011/4/1
N2 - 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.
AB - 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.
KW - 1-93 region of apolipoprotein A-I
KW - [1-93]ApoA-I
KW - AFM
KW - ApoA-I
KW - apolipoprotein A-I
KW - atomic force microscopy
KW - ATR
KW - attenuated total reflection
KW - CD
KW - circular dichroism
KW - Fourier transform infrared spectroscopy
KW - FTIR
KW - glutathione S-transferase
KW - GST
KW - mass spectrometry
KW - MS
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U2 - 10.1016/j.jmb.2011.01.044
DO - 10.1016/j.jmb.2011.01.044
M3 - Article
C2 - 21296086
AN - SCOPUS:79952451835
VL - 407
SP - 465
EP - 476
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
SN - 0022-2836
IS - 3
ER -