Polyphosphate Metabolism in Cellular Systems

Inorganic polyphosphate (polyP) is a linear polymer of up to several hundred phosphate residues linked by high-energy phosphoanhydride bonds. Present across all kingdoms of life, polyP functions as an energy reservoir, a phosphate store and a scaffold for cation sequestration and protein interactions. Its synthesis and degradation are mediated by dedicated enzymes, such as polyphosphate kinases and phosphatases, which modulate cellular phosphate homeostasis, stress responses and signal transduction. In eukaryotes, polyP accumulates in organelles analogous to acidocalcisomes, while in bacteria it forms cytoplasmic granules contributing to phosphorus cycling. Beyond its canonical roles in metabolism, polyP influences membrane dynamics, gene regulation through inositol pyrophosphate signalling and non-canonical protein modifications. The ubiquity and versatility of polyP underscore its global significance in biotechnology, medicine and environmental remediation.

Research from Nature Portfolio

Recent studies have resolved the three-dimensional architecture of a eukaryotic enzyme complex that couples cytosolic polyP synthesis to its translocation into acidic vacuoles. High-resolution structural analysis reveals how nutrient-sensing inositol pyrophosphates trigger conformational changes in the transporter polymerase, aligning the catalytic site with a transmembrane channel to drive polyP into the lumen. Complementary work in human cells has unveiled widespread protein pyrophosphorylation as a direct consequence of inositol pyrophosphate metabolism. Tailored proteomic approaches have identified numerous endogenous pyrophosphosites on nucleolar and transcriptional regulatory proteins, demonstrating that perturbation of inositol pyrophosphate biosynthesis abrogates both pyrophosphorylation and RNA synthesis. Together, these findings illuminate fundamental mechanisms by which polyP intersects with intracellular signalling and organelle biogenesis.

Polyphosphate Metabolism in Cellular Systems publication trend

The graph below shows the total number of articles in polyphosphate metabolism in cellular systems across all publications each year (not limited to Nature Index journals).

Technical terms

Polyphosphate (polyP): A linear polymer of orthophosphate units linked by high-energy phosphoanhydride bonds, serving as an energy and phosphate reservoir.

Vacuolar transporter chaperone (VTC) complex: A multisubunit enzyme in eukaryotes that polymerises ATP into polyP and translocates it across vacuolar membranes.

Inositol pyrophosphates (PP-InsPs): Highly phosphorylated inositol derivatives that function as nutrient messengers and regulate polyP metabolism.

Exopolyphosphatase (PPX): An enzyme that hydrolyses terminal phosphate residues from polyP chains, facilitating phosphate recycling.

Pyrophosphorylation: Covalent attachment of a polyphosphate chain to a protein residue, a non-canonical post-translational modification.

References

1. Polyphosphate in food systems: Their roles and applications in foods and contribution to sustainable processing practices. Trends in Food Science & Technology (2024).
2. The cytoplasmic synthesis and coupled membrane translocation of eukaryotic polyphosphate by signal-activated VTC complex. Nature Communications (2023).
3. Structural Evolution of Bacterial Polyphosphate Degradation Enzyme for Phosphorus Cycling. Advanced Science (2024).
4. Extensive protein pyrophosphorylation revealed in human cell lines. Nature Chemical Biology (2024).