Role of Glutathione in the Accumulation of Potassium Ions in Escherichia coli under Osmotic Stress

Abstract

When Escherichia coli cells were stressed by NaCl, cellular levels of glutathione (GSH) increased, and potassium ions (K⁺) accumulated. To identify the role of the stress-induced synthesis of GSH in the accumulation of K⁺ a GSH-deficient mutant of E.coli was used. The mutant grew even in a medium with a low concentration of K⁺ after a lag of about 32 hr. In such cells grown under osmotic stress in this medium, K⁺ did not accumulate in the lag phase. In the logarithmic phase, however, intracellular levels of K⁺ increased in spite of the lack of intracellular GSH. In a medium with the usual K⁺ concentration, K⁺ accumulated in a pattern similar to that of the parent strain in both phases. These results showed that GSH participates in the accumulation of K⁺ in cells under osmotic stress only in the lag phase in medium with little K⁺.