Atomic structures of fibrillar segments of hIAPP suggest tightly mated β-sheets are important for cytotoxicity

Pascal Krotee; Jose A Rodriguez; Michael R Sawaya; Duilio Cascio; Francis E Reyes; Dan Shi; Johan Hattne; Brent L Nannenga; Marie E Oskarsson; Stephan Philipp; Sarah Griner; Lin Jiang; Charles G Glabe; Gunilla T Westermark; Tamir Gonen; David S Eisenberg

doi:10.7554/eLife.19273

Atomic structures of fibrillar segments of hIAPP suggest tightly mated β-sheets are important for cytotoxicity

Elife. 2017 Jan 3:6:e19273. doi: 10.7554/eLife.19273.

Authors

Pascal Krotee^{1

2

3

4}, Jose A Rodriguez^{1

2

4}, Michael R Sawaya^{1

2

4}, Duilio Cascio^{1

2

4}, Francis E Reyes⁵, Dan Shi⁵, Johan Hattne⁵, Brent L Nannenga⁵, Marie E Oskarsson⁶, Stephan Philipp⁷, Sarah Griner^{1

2

4}, Lin Jiang^{3

8

9}, Charles G Glabe^{7

10}, Gunilla T Westermark⁶, Tamir Gonen⁵, David S Eisenberg^{1

2

3

4}

Affiliations

¹ Department of Biological Chemistry, Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, United States.
² Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, United States.
³ Molecular Biology Institute, University of California, Los Angeles, Los Angeles, United States.
⁴ UCLA-DOE Institute, University of California, Los Angeles, Los Angeles, United States.
⁵ Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States.
⁶ Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
⁷ Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, United States.
⁸ Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States.
⁹ Brain Research Institute (BRI), University of California, Los Angeles, Los Angeles, United States.
¹⁰ Biochemistry Department, Faculty of Science and Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.

Abstract

hIAPP fibrils are associated with Type-II Diabetes, but the link of hIAPP structure to islet cell death remains elusive. Here we observe that hIAPP fibrils are cytotoxic to cultured pancreatic β-cells, leading us to determine the structure and cytotoxicity of protein segments composing the amyloid spine of hIAPP. Using the cryoEM method MicroED, we discover that one segment, 19-29 S20G, forms pairs of β-sheets mated by a dry interface that share structural features with and are similarly cytotoxic to full-length hIAPP fibrils. In contrast, a second segment, 15-25 WT, forms non-toxic labile β-sheets. These segments possess different structures and cytotoxic effects, however, both can seed full-length hIAPP, and cause hIAPP to take on the cytotoxic and structural features of that segment. These results suggest that protein segment structures represent polymorphs of their parent protein and that segment 19-29 S20G may serve as a model for the toxic spine of hIAPP.

Keywords: MicroED; Type-II Diabetes; amyloid fibril; biochemistry; biophysics; cytotoxicity; human; islet amyloid polypeptide; structural biology.

Publication types

Research Support, Non-U.S. Gov't
Research Support, N.I.H., Extramural

MeSH terms

Amyloid / chemistry*
Amyloid / toxicity*
Cell Survival / drug effects
Cells, Cultured
Cryoelectron Microscopy
Humans
Insulin-Secreting Cells / drug effects*
Insulin-Secreting Cells / physiology*
Islet Amyloid Polypeptide / chemistry*
Islet Amyloid Polypeptide / toxicity*
Protein Conformation, beta-Strand

Substances

Amyloid
Islet Amyloid Polypeptide

Abstract

Publication types

MeSH terms

Substances

Grants and funding