FIG 6 .

Kinetic characterization of succinate oxidation by IMVs of WT and Δsdh1 mutant E. coli and M. smegmatis. Succinate dehydrogenase activities in IMVs of WT and Δsdh1 mutant E. coli and M. smegmatis strains were measured with the PES-DCIP assay (A) or a Clark O₂ electrode-based method (B). IMVs of E. coli were prepared from cells grown aerobically in LB medium at 37°C. MG1655, E. coli WT; RP437, E. coli ΔfrdABCD ΔsdhABCD double mutant; pFAS, E. coli overexpressing the sdhABCD operon; pH3, E. coli overexpressing the frdABCD operon. (C and D) Rates of succinate oxidation by WT and Δsdh1 mutant M. smegmatis IMVs prepared from cells grown under normoxic (C) and hypoxic (D) conditions in HdB minimal medium supplemented with 30 mM succinate. Data were analyzed by nonlinear least-squares regression of the Michaelis-Menten equation with GraphPad Prism 6, and V_max and K_m data are summarized in Table S3 in the supplemental material. WT, solid squares; SDH2 (Δsdh1 deletion mutant strain), solid triangles. Error bars indicate the standard error of a biological triplicate.