Structural highlights
FunctionIAPP_HUMAN Selectively inhibits insulin-stimulated glucose utilization and glycogen deposition in muscle, while not affecting adipocyte glucose metabolism. Publication Abstract from PubMedhIAPP 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 beta-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 beta-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 beta-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. Atomic structures of fibrillar segments of hIAPP suggest tightly mated beta-sheets are important for cytotoxicity.,Krotee P, Rodriguez JA, Sawaya MR, Cascio D, Reyes FE, Shi D, Hattne J, Nannenga BL, Oskarsson ME, Philipp S, Griner S, Jiang L, Glabe CG, Westermark GT, Gonen T, Eisenberg DS Elife. 2017 Jan 3;6. doi: 10.7554/eLife.19273. PMID:28045370[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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