PT  - JOURNAL ARTICLE
AU  - Bikash R. Sahoo
AU  - Pritam Kumar Panda
AU  - Wenguang Liang
AU  - Wei-Jen Tang
AU  - Rajeev Ahuja
AU  - Ayyalusamy Ramamoorthy
TI  - Degradation of Alzheimer’s amyloid-β by a catalytically inactive insulin-degrading enzyme
AID  - 10.1101/2020.04.23.057505
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2020.04.23.057505
4099  - http://biorxiv.org/content/early/2021/03/24/2020.04.23.057505.short
4100  - http://biorxiv.org/content/early/2021/03/24/2020.04.23.057505.full
AB  - It is known that insulin-degrading-enzyme (IDE) plays a crucial role in the clearance of Alzheimer’s amyloid-β (Aβ). The cysteine-free IDE mutant (cf-E111Q-IDE) is catalytically inactive against insulin, but its effect on Aβ degradation is unknown that would help in the allosteric modulation of the enzyme activity. Herein, the degradation of Aβ(1-40) by cf-E111Q-IDE via a non-chaperone mechanism is demonstrated by NMR and LC-MS, and the aggregation of fragmented peptides is characterized using fluorescence and electron microscopy. cf-E111Q-IDE presented a reduced effect on the aggregation kinetics of Aβ(1-40) when compared with the wild-type IDE. Whereas LC-MS and diffusion ordered NMR spectroscopy revealed the generation of Aβ fragments by both wild-type and cf-E111Q-IDE. The aggregation propensities and the difference in the morphological phenotype of the full-length Aβ(1-40) and its fragments are explained using multi-microseconds molecular dynamics simulations. Notably, our results reveal that zinc binding to Aβ(1-40) inactivates cf-E111Q-IDE’s catalytic function, whereas zinc removal restores its function as evidenced from high-speed AFM, electron microscopy, chromatography, and NMR results. These findings emphasize the catalytic role of cf-E111Q-IDE on Aβ degradation and urge the development of zinc chelators as an alternative therapeutic strategy that switches on/off IDE’s function.Competing Interest StatementThe authors have declared no competing interest.