Figure 3.

Mtb expresses lldD1, but LldD1 does not oxidize various α-hydroxy acids. (a) To determine whether lldD1 is expressed in Mtb H37Rv growing at aerobic conditions on lactate, mRNA levels were measured by absolute quantification in RT-PCR. (b) To confirm the specific activity of LldD1 towards a selection of α-hydroxy acids, the Mtb H37Rv wild type, the ΔlldD1 mutant and the ΔlldD2 mutant were grown in rich culture medium, and enzyme activity assays were performed with cell extracts using lactate, DL-phenyllactate, α-hydroxybutyrate, glycolate, or malate as substrate. Enzymatic activity was detected in the wild type and the ΔlldD1 mutant. Enzymatic activity was abolished in the ΔlldD2 mutant on lactate, but also on DL-phenyllactate and α-hydroxybutyrate. Data represent the mean of three independent experiments; error bars indicate the SEM.