Cations Regulate Membrane Attachment and Functionality of DNA Nanostructures.

Diana Morzy,Roger Rubio-Sánchez,Himanshu Joshi,Ulrich F Keyser,Lorenzo Di Michele,Aleksei Aksimentiev

doi:10.1021/jacs.1c00166

Abstract

The interplay between nucleic acids and lipids underpins several key processes in molecular biology, synthetic biotechnology, vaccine technology, and nanomedicine. These interactions are often electrostatic in nature, and much of their rich phenomenology remains unexplored in view of the chemical diversity of lipids, the heterogeneity of their phases, and the broad range of relevant solvent conditions. Here we unravel the electrostatic interactions between zwitterionic lipid membranes and DNA nanostructures in the presence of physiologically relevant cations, with the purpose of identifying new routes to program DNA–lipid complexation and membrane-active nanodevices. We demonstrate that this interplay is influenced by both the phase of the lipid membranes and the valency of the ions and observe divalent cation bridging between nucleic acids and gel-phase bilayers. Furthermore, even in the presence of hydrophobic modifications on the DNA, we find that cations are still required to enable DNA adhesion to liquid-phase membranes. We show that the latter mechanism can be exploited to control the degree of attachment of cholesterol-modified DNA nanostructures by modifying their overall hydrophobicity and charge. Besides their biological relevance, the interaction mechanisms we explored hold great practical potential in the design of biomimetic nanodevices, as we show by constructing an ion-regulated DNA-based synthetic enzyme.

Highlights

Understanding the interplay between nucleic acids (NA) and lipids is crucial for unravelling various biological processes as well as for the development of techniques and devices in bioengineering and nanomedicine
Adding to this already intricate picture is the fact that these nanosystems exist in complex solvent conditions, where ions of different valency and size are present at varying concentrations, and can screen or enhance Coulomb interactions.[26−29] Accounting for the effect of ions is critical to inform the design of both NA−lipid formulations and membrane-active DNA nanodevices
We incubated Giant unilamellar vesicles (GUVs) prepared from DPPC lipids with short, fluorescently labeled 36 bp DNA duplexes (Figure S1, oligonucleotides sequences in Table S1) using buffers with and without added salt

Summary

Introduction

Understanding the interplay between nucleic acids (NA) and lipids is crucial for unravelling various biological processes as well as for the development of techniques and devices in bioengineering and nanomedicine. Electrostatic forces are key to NA−lipid interactions, in view of the strong negative charge of nucleic acid backbones[24] and the diverse charge architectures found in lipid headgroups.[25] Adding to this already intricate picture is the fact that these nanosystems exist in complex solvent conditions, where ions of different valency and size are present at varying concentrations, and can screen or enhance Coulomb interactions.[26−29] Accounting for the effect of (physiological) ions is critical to inform the design of both NA−lipid formulations and membrane-active DNA nanodevices The latter, in particular, often feature complex and programmable morphologies, charge distributions, and chemical modifications,[9,13,30] whose coupling with the electrostatic effects mediated by cations could unlock novel functionalities

Results

Discussion

Conclusion