title: Design of a single-chain polypeptide tetrahedron assembled from coiled-coil segments.
abstract: Protein structures evolved through a complex interplay of cooperative interactions, and it is still very challenging to design new protein folds de novo. Here we present a strategy to design self-assembling polypeptide nanostructured polyhedra based on modularization using orthogonal dimerizing segments. We designed and experimentally demonstrated the formation of the tetrahedron that self-assembles from a single polypeptide chain comprising 12 concatenated coiled coil-forming segments separated by flexible peptide hinges. The path of the polypeptide chain is guided by a defined order of segments that traverse each of the six edges of the tetrahedron exactly twice, forming coiled-coil dimers with their corresponding partners. The coincidence of the polypeptide termini in the same vertex is demonstrated by reconstituting a split fluorescent protein in the polypeptide with the correct tetrahedral topology. Polypeptides with a deleted or scrambled segment order fail to self-assemble correctly. This design platform provides a foundation for constructing new topological polypeptide folds based on the set of orthogonal interacting polypeptide segments.
authors.affiliation: Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia.
authors.forename: Helena
authors.initials: H
authors.lastname: Gradišar
authors.forename: Sabina
authors.initials: S
authors.lastname: Božič
authors.forename: Tibor
authors.initials: T
authors.lastname: Doles
authors.forename: Damjan
authors.initials: D
authors.lastname: Vengust
authors.forename: Iva
authors.initials: I
authors.lastname: Hafner-Bratkovič
authors.forename: Alenka
authors.initials: A
authors.lastname: Mertelj
authors.forename: Ben
authors.initials: B
authors.lastname: Webb
authors.forename: Andrej
authors.initials: A
authors.lastname: Šali
authors.forename: Sandi
authors.initials: S
authors.lastname: Klavžar
authors.forename: Roman
authors.initials: R
authors.lastname: Jerala
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry; D019281:Dimerization; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D015202:Protein Engineering / Q000379:methods*
chemical_list: D010455:Peptides; D004247:DNA