Induction of the manganese-containing superoxide dismutase in Escherichia coli by nalidixic acid and by iron chelators (original) (raw)

Abstract Nalidixic acid caused a significant increase in the Mn-containing superoxide dismutase (MnSOD) of Escherichia coli. The maximum stimulatory effect of nalidixic acid on MnSOD biosynthesis was observed at 0.1 mM. The stimulatory effect of nalidixic acid was not due to increases in the intracellular flux of O−2, but rather to its ability to chelate Fe2+. Furthermore, 2,2′-dipyridyl and 1,10-phenanthroline were shown to cause a 7- to 20-fold increase in the MnSOD of E. coli. It is proposed that the repressor for MnSOD is an iron-containing protein.