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The effect of yeast red pigment on amyloid-β (Aβ) aggregation and fibril growth was studied in yeasts, fruit flies and in vitro. Yeast strains accumulating red pigment (red strains) contained less amyloid and had better survival rates compared to isogenic strains without red pigment accumulation (white strains). Confocal and fluorescent microscopy was used to visualise fluorescent Aβ-GFP aggregates. Yeast cells containing less red pigment had more Aβ-GFP aggregates despite the lower level of overall GFP fluorescence. Western blot analysis with anti-GFP, anti-Aβ and A11 antibodies also revealed that red cells contained a considerably lower amount of Aβ GFP aggregates as compared to white cells. Similar results were obtained with exogenous red pigment that was able to penetrate yeast cells. In vitro experiments with thioflavine and TEM showed that red pigment effectively decreased Aβ fibril growth. Transgenic flies expressing Aβ were cultivated on medium containing red and white isogenic yeast strains. Flies cultivated on red strains had a significant decrease in Aβ accumulation levels and brain neurodegeneration. They also demonstrated better memory and learning indexes and higher locomotor ability. [ABSTRACT FROM AUTHOR]

Bacteria and archaea deploy diverse, sophisticated defence systems to counter virus infection, yet many immunity mechanisms remain poorly understood. Here, we characterise the Kiwa defence system as a membrane-associated supercomplex that senses changes in the membrane induced by phage infection and plasmid conjugation. This supercomplex, comprising KwaA tetramers bound to KwaB dimers, as its basic repeating unit, detects structural stress via KwaA, activating KwaB, which binds ejected phage DNA through its DUF4868 domain, stalling phage DNA replication forks and thus disrupting replication and late transcription. We show that phage-encoded DNA mimic protein Gam, which inhibits RecBCD, also targets Kiwa through KwaB recognition. However, Gam binding to one defence system precludes its inhibition of the other. These findings reveal a distinct mechanism of bacterial immune coordination, where sensing of membrane disruptions and inhibitor partitioning enhance protection against phages and plasmids., Competing Interests: Declaration of interests The authors declare no competing interests.