Prion-inducing domain 2–114 of yeast Sup35 protein transforms in vitro into amyloid-like filaments |
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| Authors: | Chih-Yen King, Peter Tittmann, Heinz Gross, Roland Gebert, Markus Aebi, Kurt Wü thrich |
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| Affiliation: | Chih-Yen King, Peter Tittmann, Heinz Gross, Roland Gebert, Markus Aebi, and Kurt Wüthrich |
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| Abstract: | The yeast non-Mendelian genetic factor [PSI], which enhances the efficiency of tRNA-mediated nonsense suppression in Saccharomyces cerevisiae, is thought to be an abnormal cellular isoform of the Sup35 protein. Genetic studies have established that the N-terminal part of the Sup35 protein is sufficient for the genesis as well as the maintenance of [PSI]. Here we demonstrate that the N-terminal polypeptide fragment consisting of residues 2–114 of Sup35p, Sup35pN, spontaneously aggregates to form thin filaments in vitro. The filaments show a β-sheet-type circular dichroism spectrum, exhibit increased protease resistance, and show amyloid-like optical properties. It is further shown that filament growth in freshly prepared Sup35pN solutions can be induced by seeding with a dilute suspension of preformed filaments. These results suggest that the abnormal cellular isoform of Sup35p is an amyloid-like aggregate and further indicate that seeding might be responsible for the maintenance of the [PSI] element in vivo. |
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