Degradation of Alzheimer's Amyloid-β by a Catalytically Inactive Insulin-Degrading Enzyme. Issue 13 (25th June 2021)

• Record Type: Journal Article
• Authors: Sahoo, Bikash R.; Panda, Pritam Kumar; Liang, Wenguang; Tang, Wei-Jen; Ahuja, Rajeev; Ramamoorthy, Ayyalusamy
• Is Part Of: Journal of molecular biology. Volume 433:Issue 13(2021)
• Publication Date: 2021-06-25
• Subjects: Amyloid-beta -- Insulin degrading enzyme -- Amyloid degradation -- Aβ(1–40) -- Alzheimer's disease; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2021.166993
• Languages: English
• ISSNs: 0022-2836

Abstract

Graphical abstract: Highlights: Degradation of Aβ by E111Q-IDE via a non-chaperonin mechanism is demonstrated. Zinc binding to Aβ was found to form aggregates that do not fit to the IDE's catalytic cavity. Zinc binding to Aβ inactivates E111Q-IDE's catalytic function, whereas zinc removal restores its function. E111Q-IDE presented a reduced activity on Aβ aggregation kinetics when compared with the wild-type IDE. Abstract: 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.