Department of Biochemical Sciences, University of Florence, Florence, Italy.
Nat Chem Biol. 2010 Feb;6(2):140-7. doi: 10.1038/nchembio.283. Epub 2010 Jan 10.
The aberrant assembly of peptides and proteins into fibrillar aggregates proceeds through oligomeric intermediates that are thought to be the primary pathogenic species in many protein deposition diseases. We describe two types of oligomers formed by the HypF-N protein that are morphologically and tinctorially similar, as detected with atomic force microscopy and thioflavin T assays, though one is benign when added to cell cultures whereas the other is toxic. Structural investigation at a residue-specific level using site-directed labeling with pyrene indicated differences in the packing of the hydrophobic interactions between adjacent protein molecules in the oligomers. The lower degree of hydrophobic packing was found to correlate with a higher ability to penetrate the cell membrane and cause an influx of Ca(2+) ions. Our findings suggest that structural flexibility and hydrophobic exposure are primary determinants of the ability of oligomeric assemblies to cause cellular dysfunction and its consequences, such as neurodegeneration.
异常聚集的肽和蛋白质形成纤维状聚集物，通过寡聚中间体进行，这些寡聚中间体被认为是许多蛋白质沉积疾病的主要致病物质。我们描述了由 HypF-N 蛋白形成的两种形态和染色相似的寡聚体，这是通过原子力显微镜和硫黄素 T 检测到的，尽管一种添加到细胞培养物中时是良性的，而另一种是有毒的。使用带有芘的定点标记进行的残基特异性结构研究表明，寡聚体中相邻蛋白质分子之间的疏水相互作用的包装方式存在差异。发现较低的疏水性包装程度与更高的穿透细胞膜并导致钙离子流入的能力相关。我们的发现表明，结构灵活性和疏水性暴露是寡聚体组装引起细胞功能障碍及其后果（如神经退行性变）的主要决定因素。
