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Atomic Structures of Peptide Self-Assembly Mimics
Koki Makabe, Dan McEIheny, Valentia Tereshko, Aaron Hilyard, Grzegorz Gawlak, Shude Yan, Akiko Koide and Shohei Koide
Proceedings of the National Academy of Sciences of the United States of America
Vol. 103, No. 47 (Nov. 21, 2006), pp. 17753-17758
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/30052535
Page Count: 6
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Although the β-rich self-assemblies are a major structural class for polypeptides and the focus of intense research, little is known about their atomic structures and dynamics due to their insoluble and noncrystalline nature. We developed a protein engineering strategy that captures a self-assembly segment in a water-soluble molecule. A predefined number of self-assembling peptide units are linked, and the β-sheet ends are capped to prevent aggregation, which yields a mono-dispersed soluble protein. We tested this strategy by using Borrelia outer surface protein (OspA) whose single-layer β-sheet located between two globular domains consists of two β-hairpin units and thus can be considered as a prototype of self-assembly. We constructed self-assembly mimics of different sizes and determined their atomic structures using x-ray crystallography and NMR spectroscopy. Highly regular β-sheet geometries were maintained in these structures, and peptide units had a nearly identical conformation, supporting the concept that a peptide in the regular β-geometry is primed for self-assembly. However, we found small but significant differences in the relative orientation between adjacent peptide units in terms of β-sheet twist and bend, suggesting their inherent flexibility. Modeling shows how this conformational diversity, when propagated over a large number of peptide units, can lead to a substantial degree of nanoscale polymorphism of self-assemblies.
Proceedings of the National Academy of Sciences of the United States of America © 2006 National Academy of Sciences