FIGURE 5.

A, growth of wild type (●) and Δtpk3 (○) cells in the presence of an antioxidant. Cells were grown aerobically in minimal medium containing 0.2% (w/v) dl-lactate and 5 mm N-acetylcysteine. Growth was measured at 600 nm as described under “Experimental Procedures.” B, cytochrome content of wild type (black bars) and Δtpk3 (white bars) cells grown in the presence of an antioxidant. Cytochrome content was determined as described under “Experimental Procedures.” Results are mean ± S.D. of at least three measurements performed on three independent cell cultures. C, respiratory rates of wild type and Δtpk3 cells grown in the presence of an antioxidant. Wild type (black) and Δtpk3 (white) respiratory rates were assessed on cells grown aerobically in minimal medium containing 0.2% (w/v) dl-lactate and 5 mm N-acetylcysteine. Spontaneous respiratory rate was directly assessed on cells from the growth medium. The respiratory rate in the absence of phosphorylation (indicated by triethyltin (TET)) was assessed in the presence of 0.2 mm triethyltin, and the uncoupled respiratory rate was assessed in the presence of 40 μm carbonyl cyanide p-chlorophenylhydrazone (CCCP), as described under “Experimental Procedures.” Results are mean ± S.D. of at least three measurements performed on three independent cell cultures.