A Bacterial Mutant with Impaired Potassium Transport

Abstract

THE transport of substances across cell membranes against electrochemical potential gradients is attributed to the operation of energy-dependent pumps in the cell membrane. However, the exact chemical nature of these pumps and their link to metabolic energy sources remain unknown. The purpose of the present communication is to report the isolation of a genetic variant of the bacterium Escherichia coli (strain K-12) which differs from the original strain (prototroph) with respect to the accumulation and metabolism of intracellular potassium. (Since this communication was submitted, M. Lubin and D. Kessel, Biochem. and Biophys. Res. Comm., 2, 249 (1960), have discussed a similar topic.) Preliminary evidence demonstrates that, whereas the prototroph transports potassium into the cell with a half-time of 3½ min., the potassium mutant transports potassium at a rate so slow as to be scarcely detectable.