Destabilizing interactions among [PSI(+)] and [PIN(+)] yeast prion variants

Area of Science:

• Biochemistry
• Molecular Biology
• Prion Biology

Background:

• The yeast proteins Sup35 and Rnq1 form noninfectious [psi-] and [pin-] states, respectively.
• These proteins can also adopt infectious amyloid-like prion forms: [PSI+] and [PIN+].
• Previous research indicated that [PSI+] and [PIN+] prions can enhance each other's initial formation.

Purpose of the Study:

• To investigate the impact of specific prion variants on the stable inheritance of heterologous prions.
• To determine if interactions between prion variants affect their propagation.
• To explore the implications of these interactions for understanding amyloid protein behavior.

Main Methods:

• Utilizing yeast models expressing Sup35 and Rnq1 proteins.
• Introducing specific prion variants ([PSI+] and [PIN+]) into yeast strains.
• Observing and quantifying the inheritance patterns of these prions.
• Employing fluorescence microscopy to analyze Rnq1-green fluorescent protein fusion patterns.

Main Results:

• Specific prion variants of [PSI+] and [PIN+] were found to disrupt each other's stable inheritance.
• [PSI+] acquisition impeded the inheritance of certain [PIN+] variants.
• Some [PIN+] variants impaired weak [PSI+] inheritance but not strong [PSI+] variants.
• A specific [PIN+] variant, characterized by a single-dot fluorescence pattern, destabilized [PSI+], while a multiple-dot pattern variant did not.

Conclusions:

• The destabilization of prions by other prion variants is dependent on the specific variants involved.
• These findings highlight the complex interplay between different prion strains.
• Understanding these interactions may offer insights into amyloid protein behavior in other systems, including human diseases.