DNA Origami Directed Virus Capsid Polymorphism

Most known viruses protect their genome by encapsulating it inside a protein capsid. Viral capsids can adopt various geometries, most iconically characterized by icosahedral or helical symmetries. The assembly process of native capsids is highly cooperative and governed by the protein geometry, protein-protein as well as protein-nucleic acid interactions. Importantly, the high control over the size and shape of virus capsids would have advantages in the development of new vaccines and delivery systems. However, tools to direct the assembly process in a programmable manner are exceedingly elusive or strictly limited to specific structures. Here, we introduce a modular approach by demonstrating DNA origami directed polymorphism of single protein subunit capsids. We achieve control over the capsid shape, size, and topology by employing user-defined DNA origami nanostructures as binding and assembly platforms for the capsid proteins. Binding assays and single-particle cryo-electron microscopy reconstruction show that the DNA origami nanoshapes are efficiently encapsulated within the capsid. Further, we observe that helical arrangement of hexameric capsomers is the preferred mode of packing, while a negative curvature of the origami structure is not well tolerated. The capsid proteins assemble on DNA origami in single- or double-layer configurations depending on the applied stoichiometry. In addition, the obtained viral capsid coatings are able to efficiently shield the encapsulated DNA origami from nuclease degradation. Our approach is, moreover, not limited to a single type of virus capsomers and can also be applied to RNA–DNA origami structures. We have for example demonstrated folded mRNA structures and identified key folding strategies to enable protein translation, without a separate origami unfolding step. Therefore, these findings may in addition find direct implementations in next-generation cargo protection and targeting strategies.<br/><br/>I. Seitz et al. <i>Nature Nanotechnology</i>, 2023, in press. (https://doi.org/10.1038/s41565-023-01443-x)