De novo design of selective, functional channels

Channels and transporters facilitate the precise movement of ions and water across cellular membranes, driving many of life's most critical processes. Achieving function requires the translocation of defined numbers of ions or molecules: transport must therefore be highly selective and efficient. Selectivity, or the ability to allow permeation of specific ions and molecules over others, is a hallmark of channels and transporters. However, the precise molecular mechanisms that govern selectivity, particularly for protons, water, and ions, remain poorly understood. Uncovering the molecular determinants of selectivity is essential to our fundamental understanding of channel and transporter function and can inform the development of novel biomimetic membranes and transformative technologies that require precise control of ion and molecule transport. Here, we describe how we use de novo protein design methodologies to dissect contributions of pore geometry and pore chemistry to engineer novel channels with selectivity for different ions and water. Using a combination of computational and experimental biophysical techniques, including molecular dynamics (MD) simulations to electrophysiology, we are able to link protein and water dynamics to the function of these channels to better define the molecular determinants of selectivity. Despite the challenging nature of this work, we have designed functional proton channels and are actively engineering new channels with tailored selectivity for specific ions and water. This work advances our ability to design selective channels from first principles, providing insights into the fundamental mechanisms of ion and water transport.