A model for the regulation of expression of the potassium-transport operon, kdp, in Escherichia coli

Abstract

The intracellular concentration of K⁺ in Escherichia coli is known to be determined by osmolarity of the growth medium, and it is believed that the expression of the potassium-transport operon, kdp, is controlled by the turgor pressure differential between the cytoplasm and the extracellular environment. Several lines of evidence, however, argue against a strict turgor-regulation model for kdp expression. Instead, it is proposed here that kdp is controlled by one fraction of intracellular [K⁺], and that the size of this fraction is independent of the osmolarity of the culture medium.