A Designed Zn²⁺ Sensor Domain Transmits Binding Information to Transmembrane Histidine Kinases

Generating stimulus-responsive allosteric signaling de novo 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 de novo components. We generated de novo metal-binding sensor domains and substituted them for the native sensor domain of a transmembrane HK, affording chimeras that transduce signals initiated from a de novo sensor. Signaling depended on the designed sensor's stability and the interdomain linker's phase and length. These results show the usefulness of de novo design to elucidate the biochemical mechanisms and principles of transmembrane signaling.