Hydrostatic pressure effects on the stability of ataxin-3

Protein misfolding and formation of amyloids are the major event in the development of neurodegenerative diseases but the mechanism of this biological phenomenon remains to be elucidated. Here, we report the high pressure denaturation of the spinocerebellar ataxia type 3 protein Ataxin-3 from man and mouse using fluorescence spectroscopy. The two proteins carry 26 and 6 consecutive glutamines, respectively. The tryptophan fluorescence measurements indicated that at pH 7.5 and 25degreesC the pressure denaturation is reversible but with a large hysteresis in the renaturation profile for both proteins. The reversibility of the pressure-induced unfolding was confirmed by the study of 8-anilinonaphtalene-1-sulfonate (ANS) binding to both proteins. Interestingly, thioflavin-T binding is observed at high pressure, revealing a conversion of the native Ataxin-3 into a potential amyloidogenic state for both proteins. These data provide strong evidence that studying protein folding by hydrostatic pressure may contribute to a better understanding of the mechanism of protein misfolding leading to polyglutamine neurodegenerative diseases.