Changes in ATP concentration in Escherichia coli during induction of the SOS system by mitomycin C and bleomycin.

Treatment of Escherichia coli with bleomycin induced a dramatic increase in ATP concentration in the first 30 min. Afterwards, in RecA+ strains, ATP dropped quickly to values similar to those of untreated cells. Mutants of E. coli defective in either RecA protein or RecA protease activity did not show this decrease, indicating that it was due to the action of RecA protease. The increase in ATP in the first 30 min was dependent on RecBC exonuclease activity and must have been due to substrate level phosphorylation, since an uncoupler such as dinitrophenol did not affect it. Nevertheless, mitomycin C did not induce any change in ATP pools of RecA+ strains, at least during 120 min following treatment. The implications of these findings are discussed in relation to the possible pathways of activation of RecA protease.