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Extreme amyloid polymorphism in Staphylococcus aureus virulent PSMα peptides

Nir Salinas1, Jacques-Philippe Colletier2, Asher Moshe1,3

  • 1Department of Biology, Technion-Israel Institute of Technology, Haifa, 3200003, Israel.

Nature Communications
|August 31, 2018
PubMed

Insights

Staphylococcus aureus phenol-soluble modulin (PSM) peptides form diverse amyloid structures. Structural plasticity in these PSM peptides underlies their varied roles in pathogenicity and biofilm formation.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • Staphylococcus aureus phenol-soluble modulin (PSM) peptides are secreted as functional amyloids.
  • PSMs play roles in pathogenicity and can exist as full-length peptides or truncations.
  • Full-length PSMα3 forms toxic cross-α fibrils, distinct from eukaryotic cross-β amyloid fibrils.

Purpose of the Study:

  • To investigate the fibril structures formed by other PSMα peptides (PSMα1, PSMα4) and truncated PSMα3.
  • To understand the relationship between PSM structure, stability, and function.
  • To explore the structural basis for the functional diversity of S. aureus PSMα peptides.

Main Methods:

  • Structural analysis of amyloid fibrils formed by PSMα1, PSMα4, and truncated PSMα3.
  • Characterization of fibril architectures, including cross-β and atypical β-rich structures.
  • Assessment of fibril stability and functional activities (e.g., antibacterial, biofilm structuring).

Main Results:

  • PSMα1 and PSMα4 form stable, canonical cross-β amyloid fibrils via steric zipper interfaces.
  • Truncated PSMα3 exhibits antibacterial activity and forms reversible, polymorphic, atypical β-rich fibril architectures.
  • These atypical fibril architectures differ significantly from cross-α and canonical cross-β fibrils.

Conclusions:

  • S. aureus PSMα peptides display remarkable structural plasticity in their amyloid fibril formation.
  • This structural diversity contributes to the varied functional roles of PSMα peptides in S. aureus.
  • Understanding PSM amyloid structures offers insights into bacterial pathogenesis and potential therapeutic targets.

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