(511i) Insights into the Binding of ?-Wrapins to Amyloidogenic Proteins Using Simulations and Experiments

Amyloidogenic proteins aggregate into β-sheet-rich amyloid states associated with several diseases. Pancreatic islet amyloids formed by islet amyloid polypeptide (IAPP), senile plaques formed by amyloid-β (Aβ), and Lewy bodies formed by α-synuclein (α-syn) are pathological features of types II diabetes, Alzheimer’s disease, and Parkinson’s disease, respectively. Increasing evidence suggests possible molecular links between the three amyloid peptides in the aforementioned diseases [1-3], and thus, the discovery of molecules inhibiting amyloid formation of one or combinations of the amyloid proteins may be a promising therapeutic approach. β-wrapins (β-wrap proteins) are a class of proteins that bind, sequester, and thus inhibit amyloid formation by the three amyloidogenic proteins. Subtle changes of one to four mutations at the sequence level of β-wrapins can considerably change their potencies and inhibitory activities for Aβ, α-syn, or IAPP, and specific engineered β-wrapin variants bind one or combinations of the aforementioned protein monomers with submicromolar affinities [4,5,6].

In our studies, we combine computational and experimental methods to gain biophysical insights into the binding and specificity of a series of β-wrapins in complex with the three disease-associated amyloidogenic proteins Aβ, α-syn, and IAPP. In our investigation of β-wrapins in complex with both Aβ and α-syn, we identify the presence of common interactions between the current most promising dual, Aβ and α-syn, binding β-wrapin AS10 and corresponding Aβ / α-syn residues leading to dual-targeted properties, we depict the interactions which potentially act as switches diminishing the potency of β-wrapins for Aβ or α-syn, and we provide insights into the binding of the current most active β-wrapin (ZSYM73 [7]) in complex with Aβ [8], as well as the key role of polar electrostatic interactions contributing to an enhanced binding of β-wrapins to amyloidogenic proteins. We are currently investigating the interaction of β-wrapins with IAPP, and our preliminary results confirm our previous findings, and overall suggest that the use of computational association free energy calculations can be introduced to differentiate between active versus inactive engineered β-wrapins, as well as to identify the most active β-wrapins. We suggest that our studies can constitute the basis for the computational design of novel highly potent single or multi-targeted β-wrapin variants as potential therapeutics.

1. K. Jackson, G. A. Barisone, E. Diaz, L. W. Jin, C. DeCarli, F. Despa. Amylin deposition in the brain: A second amyloid in Alzheimer disease? Ann Neurol. 2013; 74(4) : 517-526.

2. I. Horvath, P. Wittung-Stafshede. Cross-talk between amyloidogenic proteins in type-2 diabetes and Parkinson’s disease. Proc. Natl. Acad. Sci. U. S. A. 2016; 113(44) : 12473-12477.

3. L. K. Clinton, M. Blurton-Jones, K. Myczek, J. Q. Trojanowski, F. M. LaFerla. Synergistic Interactions between Abeta, tau, and alpha-synuclein: acceleration of neuropathology and cognitive decline. J Neurosci. 2010; 30(21) : 7281-9.

4. W. Hoyer, C. Grönwall, A. Jonsson, S. Ståhl, T. Härd. Stabilization of a β-hairpin in monomeric Alzheimer's amyloid-β peptide inhibits amyloid formation Proc. Natl. Acad. Sci. U. S. A. 2008,;105(13) : 5099-5104.

5. E. A. Mirecka, H. Shaykhalishahi, A. Gauhar, Ş. Akgül, J. Lecher, D. Willbold, M. Stoldt, W. Hoyer. Sequestration of a β-hairpin for control of α-synuclein aggregation. Angew. Chem. Int. Ed. Engl. 2014; 53(16) : 4227-4230.

6. E. A. Mirecka, L. Gremer, S. Schiefer, F. Oesterhelt, M. Stoldt, D. Willbold, W. Hoyer. Structural Characterization of Fibrils from Recombinant Human Islet Amyloid Polypeptide by Solid-State NMR: The Central FGAILS Segment Is Part of the β-Sheet Core. J. Biotechnol. 2014; 191 : 221–227.

7. H. Lindberg, T. Härd, J. Löfblom, S. Ståhl. A truncated and dimeric format of an Affibody library on bacteria enables FACS-mediated isolation of amyloid-beta aggregation inhibitors with subnanomolar affinity. Biotechnol J. 2015; 10(11) : 1707-18.

8. A. A. Orr, M. M. Wördehoff, W. Hoyer, P. Tamamis. Uncovering the Binding and Specificity of β-Wrapins for Amyloid-β and α-Synuclein. J Phys Chem B. 2016; 120(50) : 12781-12794.