ol 4-phosphate (MEP) in the presence of a divalent metal ion (for which Mn2+ has shown to be the most effective (20)) and NADPH.Drugs such as fosmidomycin, whose structure is similar to the natural substrate, and its analogues have been developed and shown to be efficacious against the E. coli (21) and P. falciparum (22, 23) DXR enzymes.