FIG 6.

Effect of 3A4HB on UQ₈ biosynthesis and growth of F. novicida. (A) HPLC-ECD analysis of lipid extracts from 1 mg of F. novicida cells grown aerobically in Chamberlain medium with 0.4% (wt/vol) glucose as the sole carbon source and in the presence of different concentrations of 3A4HB solubilized in DMSO (a, DMSO; b, 0.01 mM; c, 0.1 mM; d, 0.25 mM; e, 0.5 mM; f, 1 mM; g, 1 mM 3A4HB plus 1 mM 4HB). The chromatograms are representative of results from three independent experiments. The peaks corresponding to UQ₈ and the UQ₁₀ standard are indicated. Compound X eluting at 6.5 min is marked. (B and C) Growth curves for F. novicida cultured under aerobic conditions in Chamberlain medium with 0.4% (wt/vol) succinate (B) or glucose (C) as the sole carbon source and in the presence of either DMSO (control), 1 mM 3A4HB, or 1 mM 3A4HB plus 100 μM 4HB. The growth under each condition (average from sextuplicate growth curves) was monitored as the change in the absorbance at 600 nm in a Tecan plate reader. (D) Mass spectrum of compound X eluting from extracts of F. novicida grown in the Chamberlain medium with 1 mM 3A4HB. H⁺ and Na⁺ adducts corresponding to this molecule are indicated. (E) Proposed structure of compound X in its oxidized form.