An Extended Polyanion Activation Surface in Insulin Degrading Enzyme

Authors

Eun Suk Song, University of KentuckyFollow
Mehmet Ozbil, University of Miami
Tingting Zhang, University of Miami
Michael Sheetz, University of KentuckyFollow
David Lee, University of California - San Diego
Danny Tran, University of California - San Diego
Sheng Li, University of California - San Diego
Rajeev Prabhakar, University of Miami
Louis B. Hersh, University of KentuckyFollow
David W. Rodgers, University of KentuckyFollow

Abstract

Insulin degrading enzyme (IDE) is believed to be the major enzyme that metabolizes insulin and has been implicated in the degradation of a number of other bioactive peptides, including amyloid beta peptide (Aβ), glucagon, amylin, and atrial natriuretic peptide. IDE is activated toward some substrates by both peptides and polyanions/anions, possibly representing an important control mechanism and a potential therapeutic target. A binding site for the polyanion ATP has previously been defined crystallographically, but mutagenesis studies suggest that other polyanion binding modes likely exist on the same extended surface that forms one wall of the substrate-binding chamber. Here we use a computational approach to define three potential ATP binding sites and mutagenesis and kinetic studies to confirm the relevance of these sites. Mutations were made at four positively charged residues (Arg 429, Arg 431, Arg 847, Lys 898) within the polyanion-binding region, converting them to polar or hydrophobic residues. We find that mutations in all three ATP binding sites strongly decrease the degree of activation by ATP and can lower basal activity and cooperativity. Computational analysis suggests conformational changes that result from polyanion binding as well as from mutating residues involved in polyanion binding. These findings indicate the presence of multiple polyanion binding modes and suggest the anion-binding surface plays an important conformational role in controlling IDE activity.

Document Type

Article

Publication Date

7-17-2015

Notes/Citation Information

Published in PLOS One, v. 10, no. 7, article e0133114, p. 1-19.

© 2015 Song et al.

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Digital Object Identifier (DOI)

http://dx.doi.org/10.1371/journal.pone.0133114

Funding Information

This work was supported by United States Department of Health and Human Services, National Institutes of Health grants NS38041 (DWR); DA02243, DA016176, and GM110787 (LBH); and AI081982, GM020501, and AI101436 (SL). RP gratefully acknowledges support from the National Science Foundation (CHE1152846). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Repository Citation

Song, Eun Suk; Ozbil, Mehmet; Zhang, Tingting; Sheetz, Michael; Lee, David; Tran, Danny; Li, Sheng; Prabhakar, Rajeev; Hersh, Louis B.; and Rodgers, David W., "An Extended Polyanion Activation Surface in Insulin Degrading Enzyme" (2015). Molecular and Cellular Biochemistry Faculty Publications. 84.
https://uknowledge.uky.edu/biochem_facpub/84