A Designed Zn Sensor Domain Transmits Binding Information to Transmembrane Histidine Kinases.

Generating stimulus-responsive allosteric signaling is a significant challenge in protein design. In natural systems like bacterial histidine kinases (HKs), signal transduction occurs when ligand binding initiates a signal that is amplified across biological membranes over long distances to induce large-scale rearrangements and phosphorylation relays. Here, we ask whether our understanding of protein design and multidomain, intramolecular signaling has progressed sufficiently to enable engineering of a HK with tunable components. We generated metal-binding sensor domains and substituted them for the native sensor domain of a transmembrane HK, affording chimeras that transduce signals initiated from a sensor. Signaling depended on the designed sensor's stability and the interdomain linker's phase and length. These results show the usefulness of design to elucidate the biochemical mechanisms and principles of transmembrane signaling.