Chemically Induced Dimerization via Nanobody Binding Facilitates in Situ Ligand Assembly and On-Demand GPCR Activation.

Methods that enable the on-demand synthesis of biologically active molecules offer the potential for a high degree of control over the timing and context of target activation; however, such approaches often require extensive engineering to implement. Tools to restrict the localization of assembly also remain limited. Here we present a new approach for stimulus-induced ligand assembly that helps to address these challenges. This methodology relies on the high affinity and specificity recognition exhibited by antibody fragments (nanobodies, Nbs). By using Nbs that recognize short peptide epitopes to create semisynthetic conjugates, we develop a bioengineering platform termed peptide epitope dimerization (PED) in which the addition of heterodimeric peptide composed of two Nb epitopes stimulates the proximity-induced synthesis of a functional ligand for the parathyroid hormone receptor-1, a G protein-coupled receptor. We further demonstrate that high efficiency assembly can be achieved on the cell surface via Nb-based delivery of template. This approach opens the door for the on-demand generation of bioactive receptor ligands preferentially at a desired biological niche.