Colloidal-like aggregation of a functional amyloid protein

Area of Science:

• Microbiology
• Biophysics
• Materials Science

Background:

• Functional amyloid proteins form extracellular networks, enhancing microbial colony stability and antibiotic resistance.
• Understanding amyloid aggregation mechanisms is crucial for applications and understanding biological processes.

Purpose of the Study:

• To investigate the pH-reduction-induced aggregation mechanism of TasA, an extracellular functional amyloid from Bacillus subtilis.
• To compare TasA aggregation with colloidal aggregation and explore the influence of nanoparticles.

Main Methods:

• Turbidity and zeta potential measurements.
• Electron microscopy (EM) and atomic force microscopy (AFM).
• Static light scattering (SLS) and nanoparticle co-aggregation studies.

Main Results:

• TasA aggregation, induced by pH reduction, results in fiber formation.
• TasA aggregation shares similarities with colloidal aggregation, driven by surface potential modulations.
• Negatively charged nanoparticles co-aggregated with TasA, with steric hindrance observed.

Conclusions:

• TasA aggregation is a surface potential-driven process followed by rearrangement.
• The findings provide a mechanistic understanding of functional amyloid formation.
• Results can inform the design of TasA aggregation inhibitors and promoters.