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

Cs(+) was found to induce expression of the kdpFABC operon, encoding a high-affinity K(+) uptake system of Escherichia coli. Quantitative expression analyses at the transcriptional and translational levels reveal that CsCl causes much higher induction of kdpFABC than does NaCl. A decrease of the intracellular K(+) concentration is found in cells exposed to CsCl. The results indicate that kdpFABC expression is induced when the intracellular K(+) concentration is lowered. Moreover, the results imply that the signal transduction cascade mediated by KdpD and KdpE is able to integrate multiple signals.