Figure 2. Methionine Limitation during Oxidative Stress Induced by Diamide and H₂O₂ .

(A) Cells of wild-type E. coli strain W3110 growing exponentially in glucose-minimal medium were diluted into the same medium with (filled circles) or without (open circles) 0.2 mM L-methionine. Cultures were allowed to grow to an OD₆₀₀ of approximately 0.5, and then diamide was added to a final concentration of 2 mM (red) or 3 mM (blue), and growth was monitored.

(B) Cultures were grown as in (A), except that they were diluted into medium with (filled circles) or without (open circles) 0.2 mM L-homocysteine. At an OD₆₀₀ of approximately 0.5, diamide (final concentration, 2 mM) was added to one set of cultures (red).

(C) Cells of wild-type E. coli strain W3110 were grown in the presence or absence of L-methionine as described in (A). At an OD₆₀₀ of approximately 0.2, H₂O₂ was added to one set of cultures (green) to a final concentration of 3 mM (a concentration found to be high enough to induce a significant slowing of growth).

(D) Cultures were grown as in (C) except that they were diluted into medium with (filled circles) or without (open circles) 0.2 mM L-homocysteine.

Note the different time scales between (A,B) and (C,D).