Evaluating β-turn mimics as β-sheet folding nucleators
Document Type
Article
Publication Date
7-2009
Publisher
National Academy of Sciences
Abstract
β-Turns are common conformations that enable proteins to adopt globular structures, and their formation is often rate limiting for folding. β-Turn mimics, molecules that replace the i + 1 and i + 2 amino acid residues of a β-turn, are envisioned to act as folding nucleators by preorganizing the pendant polypeptide chains, thereby lowering the activation barrier for β-sheet formation. However, the crucial kinetic experiments to demonstrate that β-turn mimics can act as strong nucleators in the context of a cooperatively folding protein have not been reported. We have incorporated 6 β-turn mimics simulating varied β-turn types in place of 2 residues in an engineered β-turn 1 or β-bulge turn 1 of the Pin 1 WW domain, a three-stranded β-sheet protein. We present 2 lines of kinetic evidence that the inclusion of β-turn mimics alters β-sheet folding rates, enabling us to classify β-turn mimics into 3 categories: those that are weak nucleators but permit Pin WW folding, native-like nucleators, and strong nucleators. Strong nucleators accelerate folding relative to WW domains incorporating all α-amino acid sequences. A solution NMR structure reveals that the native Pin WW β-sheet structure is retained upon incorporating a strong E-olefin nucleator. These β-turn mimics can now be used to interrogate protein folding transition state structures and the 2 kinetic analyses presented can be used to assess the nucleation capacity of other β-turn mimics.
Recommended Citation
Fuller, A. A., Du, D., Liu, F., Davoren, J. E., Bhabha, G., Kroon, G., Case, D. A., Dyson, H. J., Powers, E. T., Wipf, P., Gruebele, M., & Kelly, J. W. (2009). Evaluating β-turn mimics as β-sheet folding nucleators. Proceedings of the National Academy of Sciences, 106(27), 11067–11072. https://doi.org/10.1073/pnas.0813012106
