| Structural highlights
Function
[IDE_HUMAN] Plays a role in the cellular breakdown of insulin, IAPP, glucagon, bradykinin, kallidin and other peptides, and thereby plays a role in intercellular peptide signaling. Degrades amyloid formed by APP and IAPP. May play a role in the degradation and clearance of naturally secreted amyloid beta-protein by neurons and microglia.[1] [2] [3]
Publication Abstract from PubMed
Insulin-degrading enzyme (IDE) selectively degrades the monomer of amyloidogenic peptides and contributes to clearance of amyloid beta (Abeta). Thus, IDE retards the progression of Alzheimer's disease. IDE possesses an enclosed catalytic chamber that engulfs and degrades its peptide substrates; however, the molecular mechanism of IDE function, including substrate access to the chamber and recognition, remains elusive. Here, we captured a unique IDE conformation by using a synthetic antibody fragment as a crystallization chaperone. An unexpected displacement of a door subdomain creates an approximately 18-A opening to the chamber. This swinging-door mechanism permits the entry of short peptides into the catalytic chamber and disrupts the catalytic site within IDE door subdomain. Given the propensity of amyloidogenic peptides to convert into beta-strands for their polymerization into amyloid fibrils, they also use such beta-strands to stabilize the disrupted catalytic site resided at IDE door subdomain for their degradation by IDE. Thus, action of the swinging door allows IDE to recognize amyloidogenicity by substrate-induced stabilization of the IDE catalytic cleft. Small angle X-ray scattering (SAXS) analysis revealed that IDE exists as a mixture of closed and open states. These open states, which are distinct from the swinging door state, permit entry of larger substrates (e.g., Abeta, insulin) to the chamber and are preferred in solution. Mutational studies confirmed the critical roles of the door subdomain and hinge loop joining the N- and C-terminal halves of IDE for catalysis. Together, our data provide insights into the conformational changes of IDE that govern the selective destruction of amyloidogenic peptides.
Conformational states and recognition of amyloidogenic peptides of human insulin-degrading enzyme.,McCord LA, Liang WG, Dowdell E, Kalas V, Hoey RJ, Koide A, Koide S, Tang WJ Proc Natl Acad Sci U S A. 2013 Aug 6. PMID:23922390[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Vekrellis K, Ye Z, Qiu WQ, Walsh D, Hartley D, Chesneau V, Rosner MR, Selkoe DJ. Neurons regulate extracellular levels of amyloid beta-protein via proteolysis by insulin-degrading enzyme. J Neurosci. 2000 Mar 1;20(5):1657-65. PMID:10684867
- ↑ Im H, Manolopoulou M, Malito E, Shen Y, Zhao J, Neant-Fery M, Sun CY, Meredith SC, Sisodia SS, Leissring MA, Tang WJ. Structure of substrate-free human insulin-degrading enzyme (IDE) and biophysical analysis of ATP-induced conformational switch of IDE. J Biol Chem. 2007 Aug 31;282(35):25453-63. Epub 2007 Jul 5. PMID:17613531 doi:10.1074/jbc.M701590200
- ↑ Malito E, Ralat LA, Manolopoulou M, Tsay JL, Wadlington NL, Tang WJ. Molecular Bases for the Recognition of Short Peptide Substrates and Cysteine-Directed Modifications of Human Insulin-Degrading Enzyme. Biochemistry. 2008 Nov 6. PMID:18986166 doi:10.1021/bi801192h
- ↑ McCord LA, Liang WG, Dowdell E, Kalas V, Hoey RJ, Koide A, Koide S, Tang WJ. Conformational states and recognition of amyloidogenic peptides of human insulin-degrading enzyme. Proc Natl Acad Sci U S A. 2013 Aug 6. PMID:23922390 doi:10.1073/pnas.1304575110
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