Probing water accessibility in HET-s(218-289) amyloid fibrils by solid-state NMR |
| |
Authors: | Van Melckebeke Hélène Schanda Paul Gath Julia Wasmer Christian Verel René Lange Adam Meier Beat H Böckmann Anja |
| |
Institution: | 1 Physical Chemistry, ETH Zürich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland2 Institut de Biologie et Chimie des Protéines, UMR 5086, CNRS/Université de Lyon 1, 7 Passage du Vercors, 69367 Lyon, France |
| |
Abstract: | Despite the importance of protein fibrils in the context of conformational diseases, information on their structure is still sparse. Hydrogen/deuterium exchange measurements of backbone amide protons allow the identification hydrogen-bonding patterns and reveal pertinent information on the amyloid β-sheet architecture. However, they provide only little information on the identity of residues exposed to solvent or buried inside the fibril core. NMR spectroscopy is a potent method for identifying solvent-accessible residues in proteins via observation of polarization transfer between chemically exchanging side-chain protons and water protons. We show here that the combined use of highly deuterated samples and fast magic-angle spinning greatly attenuates unwanted spin diffusion and allows identification of polarization exchange with the solvent in a site-specific manner. We apply this measurement protocol to HET-s(218-289) prion fibrils under different conditions (including physiological pH, where protofibrils assemble together into thicker fibrils) and demonstrate that each protofibril of HET-s(218-289), is surrounded by water, thus excluding the existence of extended dry interfibril contacts. We also show that exchangeable side-chain protons inside the hydrophobic core of HET-s(218-289) do not exchange over time intervals of weeks to months. The experiments proposed in this study can provide insight into the detailed structural features of amyloid fibrils in general. |
| |
Keywords: | H/D hydrogen/deuterium 3D three-dimensional 2D two-dimensional MAS magic-angle spinning CP cross-polarization HETCOR heteronuclear correlation spectroscopy |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|