FIG. 1.

In the absence of lipoate ligases, L. monocytogenes can grow in nutrient-rich conditions. (A) The WT and the AlA2⁻ mutant were grown in BHI medium or IMM to stationary phase (OD₆₀₀ of 0.6 for the A1A2⁻ mutant in BHI medium or 1.2 for the WT in BHI medium and IMM). Lysates containing equivalent bacterial numbers were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotted with an anti-lipoic acid (α-LA) antibody. The blot was exposed for 5 s (5 sec. exp.) or 1 min (1 min. exp.). The results of anti-LA immunoblotting after 1 min of exposure are shown to illustrate the lack of detectable lipoylation in the A1A2⁻ mutant. The E2 subunit of bacterial PDH corresponds to the 75-kDa band. The blot was stripped and reprobed with polyclonal anti-L. monocytogenes (α-L.m.) antibody to confirm equivalent levels of protein loading. (B) Bacterial growth was determined by measuring OD₆₀₀ values over time for the WT and the AlA2⁻ mutant inoculated in BHI medium and grown at 37°C with aeration in a Bioscreen growth curve analyzer. Error bars represent standard deviations.