The direct synthesis of phospho <i>enol</i> pyruvate from pyruvate by <i>Escherichia coli</i>

It is concluded that PEP-synthase plays an important role in the anaplerotic and the biosynthetic reactions which enable the organisms to grow on pyruvate as sole carbon source.

Abstract

Abstract Extracts of Escherichia coli are shown to contain an enzyme system which in the presence of Mg2+ catalyses the direct formation of phosphoenolpyruvate from pyruvate and ATP with concomitant formation of AMP and inorganic phosphate. This enzyme, which has been designated 'phosphoenolpyruvate synthase' (PEP-synthase) has been purified 80-fold and is free of pyruvate kinase activity; PEP synthesis proceeded most rapidly at pH 8 to 8.5. At pH values between 6.2 and 7.5 the enzyme can catalyse the formation of ATP and pyruvate from PEP, AMP and inorganic phosphate; if arsenate is used instead of phosphate, pyruvate andADP are produced instead. Studies of the enzymic formation ofPEP with ATP specifically labelled with 32P, and of the reverse reaction with [U-14C]AMP, suggest that the PEP-synthase reaction involves the transfer of a pyrophosphoryl-group. The physiological role of PEP-synthase has been demonstrated with mutants of E. coli devoid of the enzyme: in contrast to wild-type organisms, such mutants neither grow on pyruvate, lactate or alanine, nor form glycogen from lactate. It is thus concluded that PEP-synthase plays an important role in the anaplerotic and the biosynthetic reactions which enable the organisms to grow on pyruvate as sole carbon source.