Mechanisms of Protein Oligomerization: Inhibitor of Functional Amyloids Templates 伪-Synuclein Fibrillation

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• 作者：Istvan Horvath ; Christoph F. Weise ; Emma K. Andersson ; Erik Chorell ; Magnus Sellstedt ; Christoffer Bengtsson ; Anders Olofsson ; Scott J. Hultgren ; Matthew Chapman ; Magnus Wolf-Watz ; Fredrik Almqvist ; Pernilla Wittung-Stafshede
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：February 22, 2012
• 年：2012
• 卷：134
• 期：7
• 页码：3439-3444
• 全文大小：346K
• 年卷期：v.134,no.7(February 22, 2012)
• ISSN：1520-5126

文摘

Small organic molecules that inhibit functional bacterial amyloid fibers, curli, are promising new antibiotics. Here we investigated the mechanism by which the ring-fused 2-pyridone FN075 inhibits fibrillation of the curli protein CsgA. Using a variety of biophysical techniques, we found that FN075 promotes CsgA to form off-pathway, non-amyloidogenic oligomeric species. In light of the generic properties of amyloids, we tested whether FN075 would also affect the fibrillation reaction of human 伪-synuclein, an amyloid-forming protein involved in Parkinson鈥檚 disease. Surprisingly, FN075 stimulates 伪-synuclein amyloid fiber formation as measured by thioflavin T emission, electron microscopy (EM), and atomic force microscopy (AFM). NMR data on ¹⁵N-labeled 伪-synuclein show that upon FN075 addition, 伪-synuclein oligomers with 7 nm radius form in which the C-terminal 40 residues remain disordered and solvent exposed. The polypeptides in these oligomers contain 尾-like secondary structure, and the oligomers are detectable by AFM, EM, and size-exclusion chromatography (SEC). Taken together, FN075 triggers oligomer formation of both proteins: in the case of CsgA, the oligomers do not proceed to fibers, whereas for 伪-synuclein, the oligomers are poised to rapidly form fibers. We conclude that there is a fine balance between small-molecule inhibition and templation that depends on protein chemistry.