Cs+ induces the kdp operon of Escherichia coli by lowering the intracellular K+ concentration

Cs+ mas found to induce expression of the kdpFABC operon, encoding a high-a ffinity K+ uptake system of Escherichia coli. Quantitative expression analy ses at the transcriptional and translational levels reveal that CsCI causes much higher induction of kdpFABC than does NaCl. A decrease of the intrace llular K+ concentration is found in cells exposed to CsCI. The results indi cate that kdpFABC expression is induced when the intracellular K+ concentra tion is lowered. Moreover, the results imply that the signal transduction c ascade mediated by KdpD and KdpE is able to integrate multiple signals.