Figure 4
From: Enabling stop codon read-through translation in bacteria as a probe for amyloid aggregation
Screening the anti-amyloidogenic activity of polyphenolic compounds on WH1(R0-4)-RF1. (a) A multi-well plate assay (see Fig. 3b) in which the reading-through stop codon activity (blue colour in the lacZ-amber background) of the WH1(R0-4)-RF1 chimeras was tested in the presence of the indicated natural polyphenols. Resveratrol was the most efficient compound in reverting the read-through phenotype, i.e., lack of colour. (b) Resveratrol and EGCG (100 µM) were assayed in plates (top) and in vitro (bottom) in the lacZ-WT background, as a control for a possible effect of these compounds on β-galactosidase activity. EGCG, but not resveratrol, decreased the blue colouration (top), in a reaction not dependent on stop codon read-through. β-galactosidase assays (bottom) confirmed that, when compared with the co-solvent (DMSO), EGCG significantly decreased the activity of the enzyme, an evidence for its direct inhibition by this polyphenol. On the contrary, resveratrol apparently enhanced β-galactosidase activity. Data come from 6 independent replicas. (c) To further characterize the two more efficient compounds, their effects on the viability of bacteria expressing WH1(R3)-RF1 were checked through serial dilutions on agar plates. While resveratrol (top) did not show any significant effect on bacterial growth, colony size was consistently smaller upon EGCG treatment (bottom) in the lacZ-amber and WT backgrounds, an indication for some detrimental effect on bacterial physiology.
