FIGURE 4.

Effect of metabolic engineering of the cysteine synthetic pathway on SeMet sensitivity. TKY3030 (open circles), TKY3035 (open squares), and TKY4175 (closed squares) were grown at 30 °C for 24 h in SC-Met/Leu/Ura containing various concentrations of SeMet, and cell density was then monitored as in Fig. 2. A, comparison of TKY3030 with TKY3035 at concentrations of SeMet ranging from 0 to 4 μm. B, comparison of TKY3035 with TKY4175 at concentrations of SeMet ranging from 0 to 64 μm. C, intracellular levels of thiol compounds extracted from SeMet-treated cells. SeMet was added to the resting cultures of Fig. 3C to give a final concentration of 0.25 mm followed by incubation for 30 min. Extraction and quantification of thiol compounds were performed using the same procedures described in Fig. 3C. Data represent means ± S.E. (vertical lines) for three experiments.