Phosphoconvertases

Phosphoconvertases are a proposed family of enzymes that catalyze reversible interconversion of phosphorylated substrates, enabling the exchange of phosphate groups between molecules. Unlike canonical kinases and phosphatases, phosphoconvertases are defined by their ability to facilitate bidirectional phosphate transfer within a shared active site, rather than committing to a single direction in metabolism.

The substrate range is broad, including sugar phosphates, nucleotides, and lipid phosphatides. Reactions may produce inorganic phosphate or transfer the phosphate to alternative acceptors, depending on cellular conditions and cofactor availability.

Mechanistically, many phosphoconvertases are thought to proceed via transient phosphoenzyme intermediates and require divalent metal cofactors such as Mg2+ or Mn2+. Active-site residues such as histidine, aspartate, or serine often participate in catalysis, supporting reversible phosphorylation cycles.

Distribution and function: reports span bacteria, archaea, and eukaryotes, though well-defined examples are scarce. In cells they are proposed to participate in phosphate homeostasis, salvage of phosphorylated metabolites, and metabolic flexibility under phosphate limitation or stress.

Classification and status: phosphoconvertases are not yet recognized as a single enzyme family; rather, the term describes a functional capability that may be found in diverse folds. Ongoing research seeks to standardize criteria and establish representative assays.

History and context: the concept emerged from observations that phosphate remodeling can occur without the classical kinase/phosphatase paradigm, prompting discussion about a broader set of phosphgroup transfer activities.