Uncovering a previously unknown function of polyphosphate in polyadenylated RNA-induced amyloidogenesis of Hfq.

Polyphosphate (polyP), a ubiquitous and highly conserved biopolymer, has emerged as a potential modulator of bacterial amyloidogenesis. In bacteria, polyP contributes to the formation of dense intracellular regions associated with transcriptional silencing. Gene regulation and chromatin organization are primarily controlled by nucleoid-associated proteins (NAPs), including the highly conserved RNA chaperone Hfq. Recent studies suggest that polyP alters Hfq function, promoting genomic instability through increased mutagenesis and DNA damage. In vitro, Hfq interacts with polyP and nucleic acids to form phase-separated condensates, a process mediated by its intrinsically disordered C-terminal region (CTR). In this study, we investigated the impact of polyP on the amyloidogenic behavior of Hfq. Our results reveal that, contrary to expectations, polyP alone does not induce amyloid formation in the isolated CTR. However, in the presence of polyadenylated RNA, polyP significantly enhances Hfq amyloidogenesis. These findings suggest a previously unrecognized role for polyP in RNA-mediated phase separation using amyloid self-assembly and provide new insights into the molecular mechanisms underlying bacterial stress tolerance.