Pyridoxine 5'-phosphate synthase (PNP synthase (also often referred to as PdxJ))

Pyridoxine 5'-phosphate synthase is an enzyme (EC 2.6.99.2) that catalyzes a key multi-step ring closure reaction in the de novo biosynthesis of vitamin B6 (specifically, pyridoxine 5'-phosphate; PNP) from 1-deoxy-D-xylulose 5-phosphate (DXP) and 3-hydroxy-1-aminoacetone phosphate, yielding PNP and inorganic phosphate as products. The enzyme is encoded by the pdxJ gene and operates as a homomultimer (octamer in *E. coli*) with a TIM-barrel structural fold. PNP synthase is present in many eubacteria—including important human pathogens—but not in humans. As the last and essential step in bacterial vitamin B6 biosynthesis, it is considered a promising candidate for antimicrobial drug development, though no approved drugs targeting this enzyme currently exist. Its exclusive occurrence in certain bacteria, but not obligate parasites, has important implications for selectivity of future therapeutics.

Other names

PNP synthasePdxJ2.6.99.2 (EC number)pyridoxine 5-phosphate phospho lyase

Enzyme inhibition (for potential antibiotics, drugs would be anticipated to act as competitive or allosteric inhibitors of the enzyme's catalytic activity, preventing vitamin B6 biosynthesis in bacteria)