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Differential fibril morphologies and thermostability determine functional roles of Staphylococcus aureus PSMα1 and

Bader Rayan1, Eilon Barnea1, Alexander Khokhlov1

  • 1Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel.

Frontiers in Molecular Biosciences
|July 20, 2023
PubMed

Insights

Phenol-soluble modulins (PSMs) from Staphylococcus aureus, PSMα1 and PSMα3, form distinct amyloid structures. Their differing thermal stability influences cytotoxicity and biofilm roles, highlighting structure-function relationships in bacterial virulence.

Area of Science:

  • Microbiology
  • Biochemistry
  • Structural Biology

Background:

  • Phenol-soluble modulins (PSMs) are critical virulence factors in staphylococci.
  • PSMs self-assemble into amyloid fibrils, contributing to bacterial pathogenesis.
  • Staphylococcus aureus produces various PSMs, including homologous PSMα1 and PSMα3.

Purpose of the Study:

  • To investigate the distinct amyloid fibril structures and thermal stabilities of PSMα1 and PSMα3.
  • To elucidate the relationship between fibril morphology, thermostability, and the cytotoxic activity of these PSMs.
  • To understand the functional implications of differential fibril behavior in Staphylococcus aureus.

Main Methods:

  • Comparative analysis of PSMα1 and PSMα3 self-assembly and fibril formation.
  • Application of heat shock (80°C) to assess fibril thermostability and reversibility.
  • Evaluation of cytotoxic activity and correlation with fibril structures and disaggregation.

Main Results:

  • PSMα1 forms irreversible cross-β amyloid structures upon heat shock, losing cytotoxicity.
  • PSMα3 forms reversible cross-α fibrils that disaggregate with heat, recovering cytotoxicity.
  • Differential hydrogen bonding in β-sheets likely explains the distinct thermostability.

Conclusions:

  • The unique fibril morphologies and thermostability of PSMα1 and PSMα3 dictate their distinct functional roles.
  • PSMα1's robust fibrils contribute to biofilm stability.
  • PSMα3's reversible fibrils are crucial for its dynamic toxic mechanism and stress response.
Keywords:
PSMsamyloidcytotoxicityfibrillationthermostabililyvirulence factor

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