Published on Fri Aug 27 2021

A highly active phosphate-insensitive phosphatase is widely distributed in nature

Lidbury, I. D. E. A., Scanlan, D., Murphy, A. R. J., Christie-Oleza, J., Aguilo-Ferretjans, M. d. M., Hitchcock, A., Daniell, T.

The regeneration of bioavailable phosphate from immobilised organophosphorus represents a key process in the global phosphorus cycle. Most bacteria possess at least one of three major phosphatases, known as PhoA, PhoX and PhoD. The production and activity of these three phosphatase families is negatively regulated by phosphate availability.

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Abstract

The regeneration of bioavailable phosphate from immobilised organophosphorus represents a key process in the global phosphorus cycle and is facilitated by enzymes known as phosphatases. Most bacteria possess at least one of three major phosphatases, known as PhoA, PhoX and PhoD, whose activity is optimal under alkaline conditions. The production and activity of these three phosphatase families is negatively regulated by phosphate availability and thus these enzymes play a major role in scavenging phosphorus only during times of phosphate scarcity. Here, we reveal a previously overlooked phosphate-insensitive phosphatase, PafA, prevalent in Bacteroidetes, which is highly abundant in nature and represents a major route for the remineralisation of phosphate in the environment. Using Flavobacterium johnsoniae as the model, we reveal PafA is highly active towards phosphomonoesters. Unlike other major phosphatases, PafA is fully functional in the presence of its metabolic product, phosphate, and is essential for growth on phosphorylated carbohydrates as a sole carbon source. PafA, which is constitutively produced under all growth conditions tested, rapidly remineralises phosphomonoesters producing significant quantities of bioavailable phosphate that can cross feed into neighbouring cells. pafA is both abundant and highly expressed in the global ocean and abundant in plant rhizospheres, highlighting a new and important enzyme in the global phosphorus cycle with applied implications for agriculture as well as biogeochemical cycling. We speculate PafA expands the metabolic niche of Bacteroidetes by enabling utilisation of abundant organophosphorus substrates in the presence of excess phosphate, when other microbes are rendered incapable.