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Two prion variants of Sup35p have in-register parallel beta-sheet structures, independent of hydration

Frank Shewmaker1, Dmitry Kryndushkin, Bo Chen

  • 1Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive andKidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0830, USA.

Biochemistry
|May 5, 2009
PubMed

Insights

The [PSI(+)] prion, an amyloid form of Sup35 protein, maintains an in-register parallel beta-sheet structure in both hydrated and lyophilized states. This structural feature is crucial for prion variants and their transmission, regardless of hydration.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Prion Biology

Background:

  • The [PSI(+)] prion is a self-propagating amyloid aggregate of the Sup35 protein, a translation termination factor.
  • Amyloid structure variations in [PSI(+)] isolates can lead to distinct biological properties.
  • Understanding Sup35NM amyloid structure is key to deciphering prion variant diversity.

Purpose of the Study:

  • To investigate the structural basis of different [PSI(+)] prion variants using solid-state NMR.
  • To compare the structure of infectious Sup35NM amyloid fibrils from two prion variants.
  • To determine the impact of hydration (hydrated vs. lyophilized) on Sup35NM amyloid structure.

Main Methods:

  • Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.
  • Analysis of infectious Sup35NM amyloid fibrils from two [PSI(+)] prion variants.
  • Examination of both fully hydrated and lyophilized fibril forms.

Main Results:

  • Both [PSI(+)] prion variants exhibit an in-register parallel beta-sheet structure.
  • This structure is conserved in both hydrated and lyophilized Sup35NM amyloid fibrils.
  • Leucine residues within the M domain were confirmed to participate in the beta-sheet structure.
  • Prion transmission efficacy for [PSI(+)] (Sup35NM) and [URE3] (Ure2p) was unaffected by lyophilization.

Conclusions:

  • The in-register parallel beta-sheet structure is a conserved feature of infectious Sup35NM amyloid fibrils, irrespective of prion variant or hydration state.
  • Structural stability across hydration conditions suggests a robust mechanism for prion propagation.
  • These findings provide insights into the structural basis of prion strain diversity and transmission.

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