Design of a single chain polypeptide tetrahedron self-assembled from concatenated coiled-coil-forming segments

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Helena Gradiar, Sabina Boi, Tibor Doles1, Damjan Vengust, Iva Hafner Bratkovi, Ben Webb, Andrej ali, Sandi Klavar and Roman Jerala

Natl inst chem, Slovenia

Proteins are versatile natural nanomachines; yet, artificial polypeptide folds are challenging to create de novo. Here, we present a strategy to design self-assembling polypeptide nanostructures, based on modularization using orthogonal coiled-coil dimer-forming segments. We designed the tetrahedron that self-assembles from a single polypeptide chain comprising 12 concatenated coiled-coil-forming segments separated by flexible peptide hinges. Path of the polypeptide chain through the 4 vertices of a tetrahedron is defined by the precise sequential order of coiled-coil-forming segments that traverse each of its 6 rigid edges twice forming coiled-coil dimer with their corresponding pair segment. Split fluorescent protein, attached to the termini of the recombinant polypeptide, is reconstituted only by the formation of tetrahedral topology, while polypeptides with a deleted or scrambled segment order fail to self-assemble correctly. This technological platform provides the basis for a design of nanostructures that form new topological polypeptide folds for diverse potential biotechnological applications.