Sato Takeshi, Kienlen-Campard Pascal, Ahmed Mahiuddin, Liu Wei, Li Huilin, Elliott James I, Aimoto Saburo, Constantinescu Stefan N, Octave Jean-Noel, Smith Steven O
Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, New York 11794-5215, USA.
Biochemistry. 2006 May 2;45(17):5503-16. doi: 10.1021/bi052485f.
Amyloid fibrils associated with Alzheimer's disease and a wide range of other neurodegenerative diseases have a cross beta-sheet structure, where main chain hydrogen bonding occurs between beta-strands in the direction of the fibril axis. The surface of the beta-sheet has pronounced ridges and grooves when the individual beta-strands have a parallel orientation and the amino acids are in-register with one another. Here we show that in Abeta amyloid fibrils, Met35 packs against Gly33 in the C-terminus of Abeta40 and against Gly37 in the C-terminus of Abeta42. These packing interactions suggest that the protofilament subunits are displaced relative to one another in the Abeta40 and Abeta42 fibril structures. We take advantage of this corrugated structure to design a new class of inhibitors that prevent fibril formation by placing alternating glycine and aromatic residues on one face of a beta-strand. We show that peptide inhibitors based on a GxFxGxF framework disrupt sheet-to-sheet packing and inhibit the formation of mature Abeta fibrils as assayed by thioflavin T fluorescence, electron microscopy, and solid-state NMR spectroscopy. The alternating large and small amino acids in the GxFxGxF sequence are complementary to the corresponding amino acids in the IxGxMxG motif found in the C-terminal sequence of Abeta40 and Abeta42. Importantly, the designed peptide inhibitors significantly reduce the toxicity induced by Abeta42 on cultured rat cortical neurons.
与阿尔茨海默病及多种其他神经退行性疾病相关的淀粉样纤维具有交叉β-折叠结构，其中主链氢键在纤维轴方向的β-链之间形成。当单个β-链呈平行取向且氨基酸彼此对齐时，β-折叠表面有明显的脊和沟。在这里我们表明，在Aβ淀粉样纤维中，Met35在Aβ40的C末端与Gly33堆积，在Aβ42的C末端与Gly37堆积。这些堆积相互作用表明原纤维亚基在Aβ40和Aβ42纤维结构中相对于彼此发生了位移。我们利用这种波纹结构设计了一类新型抑制剂，通过在β-链的一面交替排列甘氨酸和芳香族残基来阻止纤维形成。我们表明，基于GxFxGxF框架的肽抑制剂会破坏片层间的堆积，并如通过硫黄素T荧光、电子显微镜和固态核磁共振光谱所测定的那样抑制成熟Aβ纤维的形成。GxFxGxF序列中交替排列的大氨基酸和小氨基酸与Aβ40和Aβ42 C末端序列中发现的IxGxMxG基序中的相应氨基酸互补。重要的是，设计的肽抑制剂显著降低了Aβ42对培养的大鼠皮质神经元诱导的毒性。
