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Molecular basis of a yeast prion species barrier

A Santoso1, P Chien, L Z Osherovich

  • 1Department of Cellular & Molecular, University of California, San Francisco 94143-0450, USA.

Cell
|February 5, 2000
PubMed

Insights

Yeast prion protein Sup35p inheritance is conserved across species, with a barrier preventing cross-species induction. This barrier is mediated by specific aggregate epitopes, allowing independent propagation of multiple yeast prion states.

Area of Science:

  • Molecular Biology
  • Yeast Genetics
  • Prion Biology

Background:

  • The yeast [PSI+] factor, a prion, propagates via self-assembling Sup35p aggregates.
  • Prion mechanisms are crucial for heritable traits in various organisms.

Purpose of the Study:

  • To investigate the conservation of Sup35p prion function across yeast species.
  • To elucidate the molecular basis of the species barrier in yeast prion propagation.
  • To identify mechanisms allowing cross-species prion induction.

Main Methods:

  • Comparative analysis of Sup35p prion function in distantly related yeasts.
  • In vitro polymerization assays to study prion induction and species barriers.
  • Chimeric protein analysis to map domains involved in barrier crossing.

Main Results:

  • Sup35p prion function and inheritance are conserved among diverse yeast species.
  • A species barrier inhibits prion induction between different yeast Sup35p variants, also observed in vitro.
  • A specific short domain was identified that enables foreign Sup35p to overcome the species barrier.
  • Multiple prion-based heritable states can propagate independently within a single cell.

Conclusions:

  • The species barrier in yeast prions arises from specific interactions at the amyloid aggregate surface, mediated by defined epitopes.
  • A novel yeast prion domain was identified, contributing to the understanding of prion diversity.
  • These findings demonstrate that distinct prion states can coexist and propagate independently within a yeast cell.

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