How Glycosaminoglycans Promote Fibrillation of Salmon Calcitonin

TY - JOUR

T1 - How Glycosaminoglycans Promote Fibrillation of Salmon Calcitonin

AU - Malmos, Kirsten G

AU - Bjerring, Morten

AU - Jessen, Christian Moestrup

AU - Nielsen, Erik Holm Toustrup

AU - Poulsen, Ebbe Toftgaard

AU - Christiansen, Gunna

AU - Vosegaard, Thomas

AU - Skrydstrup, Troels

AU - Enghild, Jan J

AU - Pedersen, Jan Skov

AU - Otzen, Daniel E

N1 - Copyright © 2016, The American Society for Biochemistry and Molecular Biology.

PY - 2016/8/5

Y1 - 2016/8/5

N2 - Glycosaminoglycans (GAGs) bind all known amyloid plaques and help store protein hormones in (acidic) granular vesicles, but the molecular mechanisms underlying these important effects are unclear. Here we investigate GAG interactions with the peptide hormone salmon calcitonin (sCT). GAGs induce fast sCT fibrillation at acidic pH and only bind monomeric sCT at acidic pH, inducing sCT helicity. Increasing GAG sulfation expands the pH range for binding. Heparin, the most highly sulfated GAG, binds sCT in the pH interval 3-7. Small angle x-ray scattering indicates that sCT monomers densely decorate and pack single heparin chains, possibly via hydrophobic patches on helical sCT. sCT fibrillates without GAGs, but heparin binding accelerates the process by decreasing the otherwise long fibrillation lag times at low pH and accelerates fibril growth rates at neutral pH. sCT·heparin complexes form β-sheet-rich heparin-covered fibrils. Solid-state NMR reveals that heparin does not alter the sCT fibrillary core around Lys 11 but makes changes to Val 8 on the exterior side of the β-strand, possibly through contacts to Lys 18. Thus GAGs significantly modulate sCT fibrillation in a pH-dependent manner by interacting with both monomeric and aggregated sCT.

AB - Glycosaminoglycans (GAGs) bind all known amyloid plaques and help store protein hormones in (acidic) granular vesicles, but the molecular mechanisms underlying these important effects are unclear. Here we investigate GAG interactions with the peptide hormone salmon calcitonin (sCT). GAGs induce fast sCT fibrillation at acidic pH and only bind monomeric sCT at acidic pH, inducing sCT helicity. Increasing GAG sulfation expands the pH range for binding. Heparin, the most highly sulfated GAG, binds sCT in the pH interval 3-7. Small angle x-ray scattering indicates that sCT monomers densely decorate and pack single heparin chains, possibly via hydrophobic patches on helical sCT. sCT fibrillates without GAGs, but heparin binding accelerates the process by decreasing the otherwise long fibrillation lag times at low pH and accelerates fibril growth rates at neutral pH. sCT·heparin complexes form β-sheet-rich heparin-covered fibrils. Solid-state NMR reveals that heparin does not alter the sCT fibrillary core around Lys 11 but makes changes to Val 8 on the exterior side of the β-strand, possibly through contacts to Lys 18. Thus GAGs significantly modulate sCT fibrillation in a pH-dependent manner by interacting with both monomeric and aggregated sCT.

UR - http://www.scopus.com/inward/record.url?scp=84982801332&partnerID=8YFLogxK

U2 - 10.1074/jbc.M116.715466

DO - 10.1074/jbc.M116.715466

M3 - Journal article

C2 - 27281819

SN - 0021-9258

VL - 291

SP - 16849

EP - 16862

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

IS - 32

ER -