The application of helix fusion methods in structural biology

Design of multi-scale protein complexes by hierarchical building block fusion

“…Our general rigid helix-fusion-based pipeline fulfills the promise of early proposals 14,34 in providing a robust and accurate procedure for generating large protein assemblies by fusing symmetric building blocks and avoiding interface design, and should streamline assembly design for applications in vaccine development, drug delivery, and biomaterials more generally. The set of structures generated here goes considerably beyond previous work with rigid helical fusions 14,16,35 , and the "WORMS" software introduced here is quite general and readily configurable to different nanomaterial design challenges. WORMS can be easily extended to other symmetric assemblies including 2D arrays and 3D crystals, and should be broadly useful for generating a wide range of protein assemblies.…”

“…In recent years, a wide range of macromolecular assemblies have been created by using metal-mediated interactions 36,37 , designed non-covalent interactions [8][9][10]38 , and fusion approaches 14,16,35 . These materials have a wide range of remarkable structures and material properties.…”

Advances in methods for atomic resolution macromolecular structure determination

“…Problems, especially attachment flexibility between the scaffold and cargo, hindered much prior work. Recent advances have been made by adapting an alpha helical fusion approach, developed earlier in the area of protein design 59 , 60 , to achieve more rigid connections between components 61 – 63 . The use of a modular adaptor system based on DARPins, as introduced by Liu et al 62 , has allowed the display and cryo-EM visualization of cargo proteins bound non-covalently to scaffolds built from symmetric protein assemblies 63 , 64 .…”

Chimeric single α-helical domains as rigid fusion protein connections for protein nanotechnology and structural biology

“…Flexible, rigid, and cleavable linkers are important components of recombinant proteins (reviewed in Chen et al, 2013). However, they often require extensive optimization or chemical crosslinking (Jeong et al, 2016) to achieve the desired rigidity between the connected domains, unless a stable secondary structure of the linker-domain transition can be predicted, as in chimeric helices (reviewed in Kwon et al, 2020).…”

“…Such a connection, when introduced as a seamless extension of an Nor C-terminal helix, or of a helix near an accessible loop, only contacts the protein of interest at a single site. Unlike in direct chimeric helix fusions between two proteins (Kwon et al, 2020), an SAH helix provides an additional spacer that separates the two connected proteins sufficiently to avoid direct contacts between them (Figure S1A), without requiring chemical crosslinking.…”