FIGURE 2.

ΔubiI cells have a decreased Q₈ content in aerobic conditions and accumulate 4-HP₈. A, quantification of cellular Q₈ content (n = 6–8) in lipid extracts from WT and ΔubiI cells containing an empty vector pBAD (vec) or pBAD-ubiI. Error bars are S.D. B, HPLC-ECD of lipid extracts from 2 mg of the same cells as in A. The peaks corresponding to Q₈, compound X, demethylmenaquinone (DMK₈), MK₈, and to the Q₁₀ standard are marked. C, HPLC-ECD of lipid extracts from 2 mg of ΔubiI cells (in black) or ΔubiH cells (in gray) grown in aerobic (dashed lines) or anaerobic conditions (solid lines). D, quantification of cellular Q₈ content of cells described in A (n = 3). Error bars are S.D. E, superimposition of the aromatic region of the ¹H NMR spectra of compound X and of commercial 2-methyl-4-hydroxyphenol (2M4HP) in D₆-ethanol. F, Chemical structure of 4-HP₈.