Minimalist design of water-soluble cross-beta architecture.
Demonstrated successes of protein design and engineering suggest significant potential to produce diverse protein architectures and assemblies beyond those found in nature. Here, we describe a new class of synthetic protein architecture through the successful design and atomic structures of water-soluble cross-beta proteins. The cross-beta motif is formed from the lamination of successive beta-sheet layers, and it is abundantly observed in the core of insoluble amyloid fibrils associated with protein-misfolding diseases. Despite its prominence, cross-beta has been designed only in the context of insoluble aggregates of peptides or proteins. Cross-beta's recalcitrance to protein engineering and conspicuous absence among the known atomic structures of natural proteins thus makes it a challenging target for design in a water-soluble form. Through comparative analysis of the cross-beta structures of fibril-forming peptides, we identified rows of hydrophobic residues ("ladders") running across beta-strands of each beta-sheet layer as a minimal component of the cross-beta motif. Grafting a single ladder of hydrophobic residues designed from the Alzheimer's amyloid-beta peptide onto a large beta-sheet protein formed a dimeric protein with a cross-beta architecture that remained water-soluble, as revealed by solution analysis and x-ray crystal structures. These results demonstrate that the cross-beta motif is a stable architecture in water-soluble polypeptides and can be readily designed. Our results provide a new route for accessing the cross-beta structure and expanding the scope of protein design.
Biancalana
Matthew
M
Department of Biochemistry and Molecular Biology, The University of Chicago, IL 60637, USA.
Makabe
Koki
K
Koide
Shohei
S
D016229:Amyloid beta-Peptides / Q000737:chemistry; D018360:Crystallography, X-Ray; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D015202:Protein Engineering / Q000379:methods*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012995:Solubility; D014867:Water / Q000737:chemistry*
D016229:Amyloid beta-Peptides; D010455:Peptides; D014867:Water