FIG. 1.

Cysteine 645 prolongs the lag phase induced by diamide in medium lacking methionine. Exponentially growing cultures of pEM14/MTD23 (wild type [WT]) and pEM15/MTD23 (C645A) were inoculated into glucose minimal morpholinepropanesulfonic acid (MOPS) medium either containing or lacking 0.2 mM l-methionine (+ Met or − Met, respectively) (17). When the cultures reached an OD at 600 nm (OD₆₀₀) of 0.2, diamide was added to a concentration of 0.9 mM. A representative trace monitoring growth by OD₆₀₀ reveals the impact that the mutation of cysteine 645 has upon the resumption of growth following diamide treatment.