Major Proteomic Changes Associated with Amyloid-Induced Biofilm Formation in Pseudomonas aeruginosa PAO1

The newly identified functional amyloids
in Pseudomonas (Fap) are associated
with increased aggregation and biofilm formation
in the opportunistic pathogen P. aeruginosa; however, whether this phenomenon can be simply ascribed to the
mechanical properties of the amyloid fibrils remains undetermined.
To gain a deeper understanding of the Fap-mediated biofilm formation,
the physiological consequences of Fap expression were investigated
using label-free protein quantification. The functional amyloids were
found to not solely act as inert structural biofilm components. Their
presence induced major changes in the global proteome of the bacterium.
These included the lowered abundance of classical virulence factors
such as elastase B and the secretion system of alkaline protease A.
Amyloid-mediated biofilm formation furthermore increased abundance
of the alginate and pyoverdine synthesis machinery, which turned P. aeruginosa PAO1 into an unexpected mucoid phenotype.
The results imply a significant impact of functional amyloids on the
physiology of P. aeruginosa with subsequent
implications for biofilm formation and chronic infections.