From Ion-Channels to Porins: Engineering DNA-Based Synthetic Counterparts

Abstract

DNA nanotechnology allows for the creation of membrane-spanning channels with customized shape and functionality. We present three novel designs with channel diameters spanning an order of magnitude from 0.8 nm to 8 nm. We utilize DNA tile assembly and scaffolded origami with two different scaffold lengths to create channels of variable size and architectural complexity. Bifunctional porphyrin- and cholesterol-tags serve as membrane anchors to facilitate insertion into the lipid membrane (J. R. Burns, K. Gopfrich et al., Angewandte Chemie, 2015). We compare the conductance of the channels and confirm the correspondence between engineered design and single-channel behaviour. Our channels span two orders of magnitude in conductance, comparable to protein pores encompassing small ion channels as well as large porins. Conductance states are dependent on transmembrane voltage (K. Gopfrich, A. Seifert, et al., ACS Nano, 2014). We demonstrate that self-assembly and membrane attachment of simple DNA channels can be achieved within a minute, making their creation scalable for applications in biology (K. Gopfrich et al., Nanoletters, 2015). Confocal imaging with ion-sensitive dyes serves as an independent proof of the cation-selective ion transport capabilities of our DNA channels. Our work showcases the versatility of artificial DNA-based pores inspired by the rich structural and functional diversity of natural membrane components.