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In vitro propagation of the prion-like state of yeast Sup35 protein

S V Paushkin1, V V Kushnirov, V N Smirnov

  • 1Institute of Experimental Cardiology, Cardiology Research Center, 3rd Cherepkovskaya Street 15A, Moscow 121552, Russia.

Science (New York, N.Y.)
|July 18, 1997
PubMed

Insights

The prion-like Sup35 protein (Sup35p) in yeast was converted to its infectious form in cell-free reactions. This study confirms the prion hypothesis for Sup35p and its role in [PSI+] propagation.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Yeast Genetics

Background:

  • The yeast genetic element [PSI+] is linked to the prion-like behavior of the Sup35 protein (Sup35p).
  • Understanding Sup35p's prion properties is crucial for deciphering protein-based inheritance.

Purpose of the Study:

  • To investigate the cell-free conversion of Sup35p into its prion-like [PSI+]-specific form.
  • To model in vitro the continuous propagation of [PSI+].
  • To validate the prion hypothesis for Sup35p.

Main Methods:

  • Cell-free conversion assays using Sup35p from [psi-] yeast cells.
  • Size fractionation of yeast cell lysates.
  • Purification of Sup35p aggregates.

Main Results:

  • Observed cell-free conversion of Sup35p to the [PSI+]-specific form (Sup35pPSI+).
  • Demonstrated repeatable conversion cycles, modeling in vitro [PSI+] propagation.
  • Found that converting activity resides exclusively in Sup35pPSI+ aggregates, supporting a nucleation model.
  • Purified Sup35pPSI+ exhibited high conversion activity.

Conclusions:

  • The findings confirm the prion hypothesis for Sup35p.
  • Sup35p aggregates are the key components driving [PSI+] propagation in vitro.
  • This work provides a robust in vitro system for studying yeast prions.

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