Supramolecular Structural Constraints on Alzheimer's -Amyloid Fibrils from Electron Microscopy and Solid-State Nuclea
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- 作者：Oleg N. Antzutkin ; Richard D. Leapman ; John J. Balbach ; and Robert Tycko
- 刊名：Biochemistry
- 出版年：2002
- 出版时间：December 24, 2002
- 年：2002
- 卷：41
- 期：51
- 页码：15436 - 15450
- 全文大小：393K
- 年卷期：v.41,no.51(December 24, 2002)
- ISSN：1520-4995
文摘
We describe electron microscopy (EM), scanning transmission electron microscopy (STEM),and solid-state nuclear magnetic resonance (NMR) measurements on amyloid fibrils formed by the 42-residue 
-amyloid peptide associated with Alzheimer's disease (A1-42) and by residues 10-35 of thefull-length peptide (A10-35). These measurements place constraints on the supramolecular structure ofthe amyloid fibrils, especially the type of -sheets present in the characteristic amyloid cross- structuralmotif and the assembly of these -sheets into a fibril. EM images of negatively stained A10-35 fibrilsand measurements of fibril mass per length (MPL) by STEM show a strong dependence of fibril morphologyand MPL on pH. A10-35 fibrils formed at pH 3.7 are single "protofilaments" with MPL equal to twicethe value expected for a single cross- layer. A10-35 fibrils formed at pH 7.4 are apparently pairs ofprotofilaments or higher order bundles. EM and STEM data for A1-42 fibrils indicate that protofilamentswith MPL equal to twice the value expected for a single cross- layer are also formed by A1-42 and thatthese protofilaments exist singly and in pairs at pH 7.4. Solid-state NMR measurements of intermoleculardistances in A10-35 fibrils, using multiple-quantum 13C NMR, 13C-13C dipolar recoupling, and 15N-13Cdipolar recoupling techniques, support the in-register parallel -sheet organization previously establishedby Lynn, Meredith, Botto, and co-workers [Benzinger et al. (1998) Proc. Natl. Acad. Sci. U.S.A. 95,13407-13412; Benzinger et al. (2000) Biochemistry 39, 3491-3499] and show that this -sheetorganization is present at pH 3.7 as well as pH 7.4 despite the differences in fibril morphology and MPL.Solid-state NMR measurements of intermolecular distances in A1-42 fibrils, which represent the firstNMR data on A1-42 fibrils, also indicate an in-register parallel -sheet organization. These results, alongwith previously reported data on A1-40 fibrils, suggest that the supramolecular structures of A10-35,A1-40, and A1-42 fibrils are quite similar. A schematic structural model of these fibrils, consistent withknown experimental EM, STEM, and solid-state NMR data, is presented.
-amyloid peptide associated with Alzheimer's disease (A1-42) and by residues 10-35 of thefull-length peptide (A10-35). These measurements place constraints on the supramolecular structure ofthe amyloid fibrils, especially the type of -sheets present in the characteristic amyloid cross- structuralmotif and the assembly of these -sheets into a fibril. EM images of negatively stained A10-35 fibrilsand measurements of fibril mass per length (MPL) by STEM show a strong dependence of fibril morphologyand MPL on pH. A10-35 fibrils formed at pH 3.7 are single "protofilaments" with MPL equal to twicethe value expected for a single cross- layer. A10-35 fibrils formed at pH 7.4 are apparently pairs ofprotofilaments or higher order bundles. EM and STEM data for A1-42 fibrils indicate that protofilamentswith MPL equal to twice the value expected for a single cross- layer are also formed by A1-42 and thatthese protofilaments exist singly and in pairs at pH 7.4. Solid-state NMR measurements of intermoleculardistances in A10-35 fibrils, using multiple-quantum 13C NMR, 13C-13C dipolar recoupling, and 15N-13Cdipolar recoupling techniques, support the in-register parallel -sheet organization previously establishedby Lynn, Meredith, Botto, and co-workers [Benzinger et al. (1998) Proc. Natl. Acad. Sci. U.S.A. 95,13407-13412; Benzinger et al. (2000) Biochemistry 39, 3491-3499] and show that this -sheetorganization is present at pH 3.7 as well as pH 7.4 despite the differences in fibril morphology and MPL.Solid-state NMR measurements of intermolecular distances in A1-42 fibrils, which represent the firstNMR data on A1-42 fibrils, also indicate an in-register parallel -sheet organization. These results, alongwith previously reported data on A1-40 fibrils, suggest that the supramolecular structures of A10-35,A1-40, and A1-42 fibrils are quite similar. A schematic structural model of these fibrils, consistent withknown experimental EM, STEM, and solid-state NMR data, is presented.