Reversible Ligand-Gated Ion Channel via the Interconversion between Hollow Single Helix and Intertwined Double Helix.

: Ligand responsiveness is one of the typical mechanisms in biological organizations to trigger the sophisticated channel switch. Here, we reported a new type of helical trimer which could undergo the transition between hollow single helix and intertwined double helix with no cavity via the complexation and decomplexation with Cu ions. In addition, the spontaneously generated 1D hollow helical tubes from single helices via π-π interactions embedded into the lipid bilayers and displayed satisfactory channel stability and efficiency. Interestingly, with the addition of Cu (I) ions and further extraction by ammonia, the disassembly and reassembly of 1D hollow helical tubes gave rise to the reversible switch of channel activity in situ inside the bilayers. The synthetic helical system provides the first model of  reversible ligand-gated ion channel by means of the dynamic transition between single and double helices, which will be available for developing intelligentized artificial nanochannels for potential biological and medicinal applications.