Bacterial Stress Bodies – Ancestral Condensates Regulating RNA Turnover and Protein Translation II

How biomolecules condense to organize subcellular processes is of fundamental significance. Nitrogen-starved Escherichia coli form a single condensate, which we termed Bacterial Stress Body (BSB). Its formation is triggered by long polyphosphate chains, which scaffold the RNA chaperone Hfq into high molecular weight complexes with distinct sequence-specific RNA and DNA binding properties. We show that polyP is crucial for the stabilization of select RNAs, the sequestration of translation- and RNA metabolism-associated proteins that likely stall protein synthesis, and the specific nucleoid-associated localization of BSBs. Together, these functions ensure bacterial survival and recovery from N-starvation. Mammalian polyphosphate associates with P-bodies but not stress granules suggesting that polyphosphate's interaction with select RNA binding proteins contributed to the evolution of functionally and compositionally distinct condensates in higher organisms. Overall design: Determination of RNA bound by Hfq during nitrogen starvation via RIP-seq of RNA bound to Hfq-mCherry from wild-type and delta-ppk E. coli strains starved for nitrogen