Head-to-tail cyclization of a heptapeptide eliminates its cytotoxicity and significantly increases its inhibition effect on amyloid β-protein fibrillation and cytotoxicity
Amyloid-β (Aβ) protein aggregation is the main hallmark of Alzheimer’s disease (AD). Inhibition of Aβ fibrillation is thus a promising therapeutic approach to the prevention and treatment of AD. Recently, we designed a heptapeptide inhibitor, LVFFARK (LK7). LK7 shows a promising inhibitory capability on Aβ fibrillation, but is prone to self-assembling and displays high cytotoxicity, which would hinder its practical application. Herein, we modified LK7 by a head-to-tail cyclization and obtained a cyclic LK7 (cLK7). cLK7 exhibits a different self-assembly behavior from LK7, and has higher stability against proteolysis than LK7 and little cytotoxicity to SHSY5Y cells. Thermodynamic analysis revealed that both LK7 and cLK7 could bind to Aβ40 by electrostatic interactions, hydrogen bonding and hydrophobic interactions, but the binding affinity of cLK7 for Aβ40 (KD = 4.96 μmol/L) is six times higher than that of LK7 (KD = 32.2 μmol/L). The strong binding enables cLK7 to stabilize the secondary structure of Aβ40 and potently inhibit its nucleation, fibrillation and cytotoxicity at extensive concentration range, whereas LK7 could only moderately inhibit Aβ40 fibrillation and cytotoxicity at low concentrations. The findings indicate that the peptide cyclization is a promising approach to enhance the performance of peptide-based amyloid inhibitors.
KeywordsAlzheimer’s disease amyloid β-protein cyclic peptide inhibition protein aggregation
Unable to display preview. Download preview PDF.
This work was supported by the National Natural Science Foundation of China (Grant Nos. 21376172, 21406160, 21528601 and 21621004) and the Natural Science Foundation of Tianjin from Tianjin Municipal Science and Technology Commission (Contract No. 16JCZDJC32300).
- 13.Fradinger E A, Monien B H, Urbanc B, Lomakin A, Tan M, Li H, Spring S M, Condron M M, Cruz L, Xie C W, Benedek G B, Bitan G. C-terminal peptides coassemble into Aβ 42 oligomers and protect neurons against Aβ 42-induced neurotoxicity. Proceedings of the National Academy of Sciences of the United States of America, 2008, 105(37): 14175–14180CrossRefGoogle Scholar
- 18.Arai T, Araya T, Sasaki D, Taniguchi A, Sato T, Sohma Y, Kanai M. Rational design and identification of a non-peptidic aggregation inhibitor of amyloid-β based on a pharmacophore motif obtained from cyclo [-Lys-Leu-Val-Phe-Phe-]. Angewandte Chemie International Edition, 2014, 53(31): 8236–8239CrossRefGoogle Scholar
- 19.Luo J H, Otero J M, Yu C H, Wärmländer S K, Gräslund A, Overhand M, Abrahams J P. Inhibiting and reversing amyloid-β peptide (1–40) fibril formation with gramicidin S and engineered analogues. Chemistry (Weinheim an der Bergstrasse, Germany), 2013, 19(51): 17338–17348Google Scholar
- 24.Ziehm T, Brener O, Groen T, Kadish I, Frenzel D, Tusche M, Kutzsche J, Reiss K, Gremer L, Nagel-Steger L, et al. Increase of positive net charge and conformational rigidity enhances the efficacy of D-enantiomeric peptides designed to eliminate cytotoxic Aβ species. ACS Chemical Neuroscience, 2016, 7(8): 1088–1096CrossRefGoogle Scholar
- 25.March D R, Abbenante G, Bergman D A, Brinkworth R I, Wickramasinghe W, Begun J, Martin J L, Fairlie D P. Substratebased cyclic peptidomimetics of Phe-Ile-Val that Inhibit HIV-1 protease using a novel enzyme-binding mode. Journal of the American Chemical Society, 1996, 118(14): 3375–3379CrossRefGoogle Scholar
- 42.Cohen S I, Linse S, Luheshi L M, Hellstrand E, White D A, Rajah L, Otzen D E, Vendruscolo M, Dobson C M, Knowles T P. Proliferation of amyloid-β 42 aggregates occurs through a secondary nucleation mechanism. Proceedings of the National Academy of Sciences of the United States of America, 2013, 110(24): 9758–9763CrossRefGoogle Scholar
- 50.Kumar S, Udgaonkar J B. Mechanisms of amyloid fibril formation by proteins. Current Science, 2010, 98(5): 639–656Google Scholar