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Life cycle of yeast prions: propagation mediated by amyloid fibrils

Yuji Inoue1

  • 1Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, FSB401, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan. uzinoue@molbio.t.u-tokyo.ac.jp

Protein and Peptide Letters
|March 12, 2009
PubMed

Insights

Yeast prions, like Sup35 and Ure2, form amyloid fibrils that are crucial for their propagation and diversity. These amyloid structures mediate protein conversion, strain variation, and replication, advancing our understanding of prion biology.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Yeast Genetics

Background:

  • Prion phenomena extend beyond mammals to organisms like Saccharomyces cerevisiae.
  • Yeast prions, such as Sup35 ([PSI+]) and Ure2 ([URE3]), are proteins with prion properties.
  • These proteins feature prion-forming regions rich in glutamine/asparagine and can adopt amyloid fibril conformations.

Purpose of the Study:

  • To elucidate the critical roles of amyloid fibrils in the life cycle of yeast prions.
  • To explore the mechanisms underlying prion propagation, strain diversity, and replication in yeast.
  • To investigate potential heterologous prion-prion interactions in yeast.

Main Methods:

  • Observational studies on yeast prion protein conformations and amyloid fibril formation.
  • Analysis of the structural conversion of normal prion proteins to abnormal forms.
  • Investigation of the role of chaperone systems, particularly Hsp104, in prion element multiplication.
  • Examination of amyloid fibril fragmentation and distribution during cell division.

Main Results:

  • Amyloid fibrils catalyze the structural conversion of normal prion proteins into abnormal forms.
  • Substructural differences in amyloid fibrils correlate with prion phenotype strain variations.
  • Amyloid fibril fragmentation, mediated by Hsp104, facilitates prion element multiplication and daughter cell distribution.
  • Evidence suggests potential cross-seeding interactions between different prion proteins within the same yeast cell.

Conclusions:

  • Yeast amyloid fibrils are central to prion replication, strain diversity, and propagation.
  • The Hsp104 chaperone system is essential for managing prion element numbers and inheritance.
  • Yeast prions serve as a valuable model for understanding fundamental prion and amyloid fibril characteristics.

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