J Biol Chem, Vol. 273, Issue 46, 30232-30238, November 13, 1998

Reversible Induction of ATP Synthesis by DNA Damage and Repair in Escherichia coli
IN VIVO NMR STUDIES

Esther Dahan-Grobgeld, Zvi Livneh^§, Antonio F. Maretzek, Sylvie Polak-Charcon^¶, Zehava Eichenbaum^§, and Hadassa Degani

From the Departments of  Biological Regulation and ^§ Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel and ^¶ Department of Pathology, Sheba Medical Center, Tel Hashomer 52621, Israel

Early metabolic events in Escherichia coli exposed to nalidixic acid, a topoisomerase II inhibitor and an inducer of the SOS system, were investigated by in vivo NMR spectroscopy, a technique that permits monitoring of bacteria under controlled physiological conditions. The energetics of AB1157 (wild type) and of its isogenic, SOS-defective mutants, recBC, lexA, and recA, were studied by ³¹P and ¹⁹F NMR before, during, and after exposure to nalidixic acid. The content of the NTP in E. coli embedded in agarose beads and perfused at 36 °C was found to be 4.3 ± 1.1 × 10¹⁸ mol/cell, yielding a concentration of ~2.7 ± 0.7 mM. Nalidixic acid induced in the wild type and mutants a rapid 2-fold increase in the content of the NTP, predominantly ATP. This induction did not involve synthesis of uracil derivatives or breakdown of RNA and caused cell proliferation to stop. Removal of nalidixic acid after 40 min of treatment rescued the cells and resulted in a decrease of ATP to control levels and resumption of proliferation. However, in recA cells, which were more sensitive to the activity of the drug, ATP elevation could not be reversed, and ATP content continued to increase faster than in control cells. The results ruled out association between the elevation of ATP and the induction of the SOS system and suggested involvement of a process reminiscent of apoptosis in the stimulation of ATP synthesis. Thus, the presence of the RecA protein was found to be essential for reversing the ATP increase and cell rescue, possibly by its function in repair of DNA damage.