Antibody-Templated Assembly of an RNA Mimic of Green Fluorescent Protein

One of the most intriguing ways'. through which nature achieves regulation of biological pathways encompasses the coordination of noncovalent interactions that bring biomolecules to be colocalized in a designated restricted space. Inspired by this mechanism, we have explored the possibility of using antibodies as bivalent biomolecular substrates for the templated assembly of a functional RNA structure. We have developed a biosupramolecular complementation assay by assembling a fluorescent Spinach aptamer, which is a synthetic RNA mimic of the Green Fluorescent Protein, from its split segments. We have employed two antigen-tagged RNA strands that, upon binding to the target antibody, are colocalized in a confined space and can reassemble into the native Spinach conformation, yielding a measurable fluorescence emission as, a function of the templating antibody concentration. We have demonstrated the generality of our approach using two different antigen/antibody systems and found that both platforms show high binding affinity, specificity for the target antibody, and enough selectivity to work in crude cellular extracts. This study highlights the potential of biosupramolecular RNA engineering for the development of innovative biomimetic tools for nanobiotechnology and bioanalytical assays.