Dendrimer-like supramolecular assembly of proteins with a tunable size and valency through stepwise iterative growth

The assembly of proteins in a programmable manner provides insight into the underlying mechanisms of protein self-assembly in nature as well as the creation of novel functional nanomaterials for practical applications. Despite many advances, however, a rational protein assembly with an easy scalability in terms of size and valency remains a challenging task. Here, we present a simple bottom-up approach to the supramolecular protein assembly with a tunable size and valency in a programmable manner. The dendrimer-like protein assembly, called a "prodrimer," was constructed using a total of three monomeric proteins: a core and two building-block proteins. The prodrimer generations were grown by a stepwise and alternate addition of a building block using two pairs of orthogonal protein-peptide interactions, leading to a higher-generation prodrimer with a mega-dalton size and multi-valency. The valency of the prodrimers at the periphery was tunable with the generation, enabling a single-step functionalization. A second-generation prodrimer functionalized with a target-specific protein binder showed a three-order of magnitude increase in binding affinity compared to a monomeric counterpart due to the avidity. The prodrimers functionalized with a targeting moiety and a cytotoxic protein cargo exhibited a highly enhanced cellular cytotoxicity, exemplifying their utility as a protein delivery platform. The present approach can be effectively used in the creation of protein architectures with new functions for biotechnological and medical applications.