Probing metazoan polyphosphate biology usingDrosophilareveals novel and conserved polyP functions

Polyphosphate exists in all life forms; however, its biological functions in metazoans are understudied. Here, we exploredDrosophilaas the first genetic model to explore polyP biology in metazoans. We first established biochemical and in situ methods to detect, quantify, and visualise polyP inDrosophila.We then engineered a FLYX system to deplete polyP in subcellular compartments in a tissue-specific manner. Using these tools, we demonstrated a spatiotemporal and subcellular compartment-specific regulation of polyP levels in various developmental stages and tissue types. We then uncovered that polyP is crucial for hemolymph clotting and developmental timing. These results indicate the evolutionarily conserved role of polyP as theex vivoaddition of polyP accelerates mammalian blood clotting. Further, the transcriptomics analysis of polyP-depleted larvae demonstrates the impact of polyP on several cellular processes including translation. These observations underscore the utility of the toolkit we developed to discover previously unknown polyP functions in metazoans.