Fig 6. CoQ₁₀ production by the human COQ2-expressing ∆ppt1 strain after treatment with 10 μg/mL Bz or 4-NB.

For the pre-culture, KH2 (Δppt1) yeast cells harboring pREP1-1stM-HsCOQ2 (A) or pREP1-4thM-HsCOQ2 (B) [10] were cultivated in 55 mL PMU medium containing 0.32 mg/mL cysteine and 0.15 μg/mL thiamine for 2 days. Cells were washed three times with distilled water and inoculated into 55 mL PMU medium containing 0.32 mg/mL cysteine (initial cell density ~1×10⁶ cells/mL) and cultivated for 2 days with rotation at 30°C. Next, 2 μg/mL PABA, 2 μg/mL PHB, 10 μg/mL Bz, or 100 μg/mL 4-NB was added to the media to test their effects. Gray bars show the CoQ₁₀ content per 50 mL of medium, and white bars show CoQ₁₀ normalized against cell number. Diamonds show cell number. Five micrograms of CoQ₆ was used as an internal standard. Data are represented as the mean ± SD of two (A) or three (B) measurements. Asterisks on bars denote statistically significant differences (**p<0.01, *p<0.05) relative to PMU + cysteine (Student’s t-test).