FIGURE 3.

Comparative analysis of strain-specific reactions catalyzed by MlghB versus DdahB and by MlghC versus DdahC. For both panels, a base reaction containing ∼0.10 mm concentrations of freshly preformed P1 was prepared by incubating GDP-d-manno-heptose with 3 μm DdahA (which was still present in the reaction), 0.10 mm NADPH, 0.03 mm NADP⁺, and 200 mm Tris-HCl, pH 8.0. All reactions were incubated at 37 °C for 30 min. For panel A, the base reaction was further incubated as such or supplemented by 7 μm MlghB and 3 μm MlghC or DdahC as indicated on the figure. For panel B, the reaction composition was the same as in panel A except that MlghB was replaced by DdahB. Note that DdahA is still present and active under these conditions and replenishes the stock of P1 substrate as long as heptose is available. P1, DdahA product and substrate of MlghB and DdahB. P4α, -β, and -γ, MlghB products. P4α is also produced by DdahB. P5α: DdahC product. P5γ, MlghC product. * denotes a small impurity present in the heptose preparation, and + denotes a small amount of NADP⁺ that was present in the NADPH stock. Integration data are provided in supplemental Table S1.