Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy.
European Molecular Biology Laboratory (EMBL), Grenoble Outstation, Grenoble, France.
Biophys J. 2020 Feb 4;118(3):676-687. doi: 10.1016/j.bpj.2019.12.025. Epub 2020 Jan 3.
Prions are pathological isoforms of the cellular prion protein that is responsible for transmissible spongiform encephalopathies (TSE). Cellular prion protein interacts with copper, Cu(II), through octarepeat and nonoctarepeat (non-OR) binding sites. The molecular details of Cu(II) coordination within the non-OR region are not well characterized yet. By the means of small angle x-ray scattering and x-ray absorption spectroscopic methods, we have investigated the effect of Cu(II) on prion protein folding and its coordination geometries when bound to the non-OR region of recombinant prion proteins (recPrP) from mammalian species considered resistant or susceptible to TSE. As the prion resistant model, we used ovine recPrP (OvPrP) carrying the protective polymorphism at residues A136, R154, and R171, whereas as TSE-susceptible models, we employed OvPrP with V136, R154, and Q171 polymorphism and bank vole recPrP. Our analysis reveals that Cu(II) affects the structural plasticity of the non-OR region, leading to a more compacted conformation. We then identified two Cu(II) coordination geometries: in the type 1 coordination observed in OvPrP at residues A136, R154, and R171, the metal is coordinated by four residues; conversely, the type 2 coordination is present in OvPrP with V136, R154, and Q171 and bank vole recPrP, where Cu(II) is coordinated by three residues and by one water molecule, making the non-OR region more exposed to the solvent. These changes in copper coordination affect the recPrP amyloid aggregation. This study may provide new insights into the molecular mechanisms governing the resistance or susceptibility of certain species to TSE.
朊病毒是细胞朊病毒蛋白的病理性异构体,负责传染性海绵状脑病 (TSE)。细胞朊病毒蛋白通过八重复和非八重复(非 OR)结合位点与铜 (Cu(II)) 相互作用。非 OR 区域内 Cu(II) 配位的分子细节尚未得到很好的描述。通过小角度 X 射线散射和 X 射线吸收光谱方法,我们研究了 Cu(II) 对折叠的影响重组朊病毒蛋白 (recPrP) 的非 OR 区域结合时,来自被认为对 TSE 具有抗性或敏感性的哺乳动物物种的朊病毒蛋白的折叠及其配位几何形状。作为朊病毒抗性模型,我们使用携带在残基 A136、R154 和 R171 处具有保护多态性的绵羊 recPrP (OvPrP),而作为 TSE 敏感性模型,我们使用携带 V136、R154 和 Q171 多态性的 OvPrP 和 bank vole recPrP。我们的分析表明,Cu(II) 会影响非 OR 区域的结构可塑性,导致更紧凑的构象。然后,我们确定了两种 Cu(II) 配位几何形状:在 OvPrP 中在残基 A136、R154 和 R171 处观察到的 1 型配位中,金属由四个残基配位;相反,在 OvPrP 中具有 V136、R154 和 Q171 和 bank vole recPrP 中存在 2 型配位,其中 Cu(II) 由三个残基和一个水分子配位,使非 OR 区域更暴露于溶剂。这些铜配位的变化会影响 recPrP 淀粉样蛋白的聚集。这项研究可能为某些物种对 TSE 的抗性或敏感性的分子机制提供新的见解。