FIGURE 5.

Conditional expression of the glucose-6-phosphate dehydrogenase zwf gene boosts reductive power and increases resistance to H₂O₂. A, diagram of the suicide expression vector pTX containing the tetracycline promoter/operator is shown. The position of R6K origin, gentamicin resistance cassette (GM^r), tetracycline repressor (tetR), FRT, tetracycline promoter elements (tet^p/o), and multiple cloning site are shown. B, pTX empty vector and pTZWF integrated into a neutral site downstream of putP were transduced into wild-type and dksA mutant bacteria. The bacteria were treated with 0.2 μg/ml anhydrotetracycline at the time of challenge with H₂O₂ in PBS. The data represent the mean percent survival ± S.E. (error bars) of three independent observations. C, NADP⁺ and NADPH pyridine nucleotides were measured at the indicated times after the addition of anhydrotetracycline to bacteria cultured in PBS. The data are the mean NADPH/NADP⁺ ratio of four independent observations collected in 3 separate days. *, p < 0.05.