Ensemble cryoEM elucidates the mechanism of insulin capture and degradation by human insulin degrading enzyme
Abstract
Insulin degrading enzyme (IDE) plays key roles in degrading peptides vital in type 2 diabetes, Alzheimer's, inflammation, and other human diseases. However, the process through which IDE recognizes peptides that tend to form amyloid fibrils remained unsolved. We used cryoEM to understand both the apo- and insulin-bound dimeric IDE states, revealing that IDE displays a large opening between the homologous ~55 kDa N- and C-terminal halves to allow selective substrate capture based on size and charge complementarity. We also used cryoEM, X-ray crystallography, SAXS, and HDX-MS to elucidate the molecular basis of how amyloidogenic peptides stabilize the disordered IDE catalytic cleft, thereby inducing selective degradation by substrate-assisted catalysis. Furthermore, our insulin-bound IDE structures explain how IDE processively degrades insulin by stochastically cutting either chain without breaking disulfide bonds. Together, our studies provide a mechanism for how IDE selectively degrades amyloidogenic peptides and offers structural insights for developing IDE-based therapies.
Data availability
Article and author information
Author details
Funding
National Institutes of Health (GM81539)
- Wei-Jen Tang
Defense Advanced Research Projects Agency (N66001-14-2-4053)
- David R Liu
Simons Foundation (349247)
- Bridget Carragher
- Clinton S Potter
National Institutes of Health (GM121964)
- Wei-Jen Tang
National Institutes of Health (GM103310)
- Bridget Carragher
- Clinton S Potter
National Institutes of Health (R35 GM118062)
- David R Liu
Howard Hughes Medical Institute
- David R Liu
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Sriram Subramaniam, National Cancer Institute, United States
Version history
- Received: November 15, 2017
- Accepted: March 28, 2018
- Accepted Manuscript published: March 29, 2018 (version 1)
- Version of Record published: April 20, 2018 (version 2)
Copyright
© 2018, Zhang et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 4,854
- views
-
- 735
- downloads
-
- 47
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.