HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplemental Research Data All Versions of this Article: ps.062486907v1 16/1/110    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Williamson, J. A. Articles by Miranker, A. D. Search for Related Content PubMed PubMed Citation Articles by Williamson, J. A. Articles by Miranker, A. D. Social Bookmarking                   What's this?

Direct detection of transient -helical states in islet amyloid polypeptide

Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA

(RECEIVED August 7, 2006; FINAL REVISION October 11, 2006; ACCEPTED October 16, 2006)

The protein islet amyloid polypeptide (IAPP) is a glucose metabolism associated hormone cosecreted with insulin by the -cells of the pancreas. In humans with type 2 diabetes, IAPP deposits as amyloid fibers. The assembly intermediates of this process are associated with -cell death. Here, we examine the rat IAPP sequence variant under physiological solution conditions. Rat IAPP is mechanistically informative for fibrillogenesis, as it samples intermediate-like states but does not progress to form amyloid. A central challenge was the development of a bacterial expression system to generate isotopically labeled IAPP without terminal tags, but which does include a eukaryotic post-translational modification. While optical spectroscopy shows IAPP to be natively unfolded, NMR chemical shifts of backbone and -carbon resonances reveal the sampling of -helical states across a continuous stretch comprising 40% of the protein. In addition, the manifestation of nonrandom coil chemical shifts is confirmed by the relative insensitivity of the amide proton chemical shifts to alterations in temperature. Intriguingly, the residues displaying helical propensity are conserved with the human sequence, suggesting a functional role for this conformational bias. The inability of rat IAPP to self assemble can be ascribed, in part, to several slowly exchanging conformations evident as multiple chemical shift assignments in the immediate vicinity of three proline residues residing outside of this helical region.

Keywords: amylin; amyloid; IAPP; NMR; -helix; type 2 diabetes; protein folding; intrinsic disorder

CiteULike

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				J. D. Knight, J. A. Williamson, and A. D. Miranker Interaction of membrane-bound islet amyloid polypeptide with soluble and crystalline insulin Protein Sci., October 1, 2008; 17(10): 1850 - 1856. [Abstract] [Full Text] [PDF]

				M. Apostolidou, S. A. Jayasinghe, and R. Langen Structure of {alpha}-Helical Membrane-bound Human Islet Amyloid Polypeptide and Its Implications for Membrane-mediated Misfolding J. Biol. Chem., June 20, 2008; 283(25): 17205 - 17210. [Abstract] [Full Text] [PDF]

				B. W. Koo, J. A. Hebda, and A. D. Miranker Amide inequivalence in the fibrillar assembly of islet amyloid polypeptide Protein Eng. Des. Sel., March 1, 2008; 21(3): 147 - 154. [Abstract] [Full Text] [PDF]