MolCraft: a hierarchical approach to the synthesis of artificial proteins

The modular structures of extant proteins and genes suggest that modern genes developed hierarchically from combinatorial assemblages of smaller primordial genetic units (microgenes). The MolCraft system described in this review is the new type of in vitro protein evolution system whose underlying concept is the hierarchical evolution of genes. In MolCraft, a microgene is initially evolved in silico and then tandemly polymerized with insertion or deletion mutations at the junctions between microgene units. Because of the junctional perturbations, proteins translated from a single microgene polymer are molecularly diverse, originating from the combinatorics of three reading frames, and are thus combinatorial polymers of three peptides. Notably, repetitiousness retained in the overall structure of proteins contributes to the formation of ordered structures, and enhances the chances of reconstituting biological activity rationally encrypted in the microgene unit. Applications of this new technology are discussed.