Ataxin-3 (AT3) triggers spinocerebellar ataxia type 3 when it carries a polyglutamine stretch expanded beyond a critical threshold. By Fourier transform infrared spectroscopy and atomic force microscopy we previously showed that a normal (AT3Q24) and an expanded (AT3Q55) variant were capable of evolving into oligomers and protofibrils at 37 degrees C, whereas only the expanded form generated irreversibly aggregated fibrils that also were associated with a network of side-chain glutamine hydrogen bonding Natalello et al. (2011) PLoS One. 6:e18789. We report here that AT3Q24, when gradually heated up to 85 degrees C, undergoes aggregation similar to that observed at 37 degrees C; in contrast, AT3Q55 only generates large, amorphous aggregates. We propose a possible interpretation of the mechanism by which temperature affects the outcome of fibrillogenesis. (C) 2012 Elsevier Masson SAS. All rights reserved.
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