Modulating kinetics of the amyloid-like aggregation of S. aureus phenol-soluble modulins by changes in pH

The
pathogen Staphylococcus aureus is recognized as one of the most frequent
causes of biofilm-associated infections. The recently identified phenol-soluble
modulin (PSM) peptides act as the key molecular effectors of staphylococcal
biofilm maturation and promote the formation of an aggregated fibril structure.
The
aim of this study was to evaluate the effect of various pH values on the
formation of functional amyloids of individual PSM peptides. Here, we combined a range of
biophysical, chemical kinetics and
microscopic techniques to address the
structure and aggregation mechanism of individual PSMs under different
conditions. We established that there is a
pH-induced switch in PSM aggregation kinetics. Different lag times and growth
of fibrils were observed, which indicates that there was no clear correlation
between the rates of fibril elongation among different PSMs. This finding confirms that pH can modulate the
aggregation properties of these peptides and suggest a deeper understanding of the
formation of aggregates, which represents an important basis for strategies to
interfere and might help in reducing the risk of biofilm-related
infections.