Phosphonate biosynthesis: isolation of the enzyme responsible for the formation of a carbon–phosphorus bond

Abstract

The first isolation of a naturally occurring phosphonate in 1959¹ led rapidly to the discovery of a variety of metabolites containing a phosphorus–carbon bond². Phosphonates have been found in bacteria, fungi, and higher organisms such as the snail schistosome vector Biomphalaria^2–6. The biosynthetic path to the P–C bond has, however, remained undefined. Thus although it was shown twenty years ago that the isotope label from [¹⁴C]glucose^7,8 or from [³²P]phosphoenolpyruvate⁸ is incorporated into 2-aminoethylphosphonate by the protozoan Tetrahymena pyriformis, the presumed stoichiometric transformation of phosphoenolpyruvate to phosphonopyruvate has never been demonstrated. Low conversions of phosphoenolpyruvate into 2-aminoethylphosphonate and the trapping of phosphonopyruvate from phosphoenolpyruvate have been reported^9–12, but these reactions have not proved reproducible, and the existence of the critical enzyme, phosphoenolpyruvate phosphonomutase, has remained notional. We now report experiments that resolve this enigma, and describe the isolation and characterization of the pure mutase from T. pyriformis.