Regulation of reversible conformational change, size switching, and immunomodulation of RNA nanocubes.

In biological systems, conformational changes and allosteric modulation play pivotal roles in regulating biological functions, such as the dynamic change of protein molecules, in response to binding or interacting with other factors such as pH, voltage, salt, light, or ligand. RNA can be manipulated and tuned with a level of simplicity that is characteristic of DNA or polymers, while displaying versatility in structure, diversity in function, and adaptability in a configuration similar to proteins. In the past, the work on the investigation of conformational change mainly focused on protein. The induced-fit and conformational capture in RNA have also been explored, such as in the study of riboswitches. Herein, we report the engineering of three-dimensional RNA nanocubes and demonstrated the operation and regulation for its configuration. We demonstrate the operation of reconfigurable RNA nanocubes whose shapes change precisely and reversibly in response to a specific trigger strand. The shape, size, and conformation can be regulated precisely and reversibly in response to the specific triggering signals. The shape and conformational conversion were observed by cryo-EM and gel electrophoresis, respectively. Harnessing the size, shape, conformation, and self-assembly capabilities of the RNA nanocube can provide a new potential use of this technology as nanocarriers for the treatment of various diseases.