On the Origin of Phosphorylated Biomolecules

Phosphorus is a key element in biology, serving in cellular replication, metabolism, and structure. The versatility of phosphorus in biology is due to several unique chemical characteristics that rely on its electronic structure and geochemical abundance. The formation of phosphorylated biomolecules and their activated precursors have hence been a major focus of prebiotic syntheses for the past 50 years. This chapter highlights the basic chemical and physical features that make phosphorus chemicals so valuable within contemporary biochemistry, the putative prebiotic routes to phosphorylated biomolecules, and a growing role for reduced oxidation state phosphorus compounds, including those derived from meteorites, in the development of life on the Earth. We distinguish three primary forms of biological phosphates that form an energetic hierarchy: (i) stable phosphorylated biomolecules that are unreactive and in which the P provides a structural or binding handle; (ii) energetic condensed phosphates including ATP which store metabolic energy; and (iii) reactive phosphorylated biomolecules which are generated during metabolism and transfer phosphates and energy to condensed phosphates for energy storage. We suggest here that: (1) precursors to modern biologic phosphates likely included reduced oxidation state phosphorus compounds; (2) ATP as the main metabolic energy transfer agent likely arose well after the origin of life, and was likely co-opted from its role as a RNA building block into its metabolic role