Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 90187, Sweden.
Department of Chemistry, Umeå University, 90187 Umeå, Sweden.
ACS Appl Mater Interfaces. 2021 Jun 16;13(23):26721-26734. doi: 10.1021/acsami.1c04163. Epub 2021 Jun 3.
Pro-inflammatory and amyloidogenic S100A9 protein is central to the amyloid-neuroinflammatory cascade in neurodegenerative diseases. Polyoxometalates (POMs) constitute a diverse group of nanomaterials, which showed potency in amyloid inhibition. Here, we have demonstrated that two selected nanosized niobium POMs, Nb and TiNb, can act as potent inhibitors of S100A9 amyloid assembly. Kinetics analysis based on ThT fluorescence experiments showed that addition of either Nb or TiNb reduces the S100A9 amyloid formation rate and amyloid quantity. Atomic force microscopy imaging demonstrated the complete absence of long S100A9 amyloid fibrils at increasing concentrations of either POM and the presence of only round-shaped and slightly elongated aggregates. Molecular dynamics simulation revealed that both Nb and TiNb bind to native S100A9 homo-dimer by forming ionic interactions with the positively charged Lys residue-rich patches on the protein surface. The acrylamide quenching of intrinsic fluorescence showed that POM binding does not perturb the Trp 88 environment. The far and near UV circular dichroism revealed no large-scale perturbation of S100A9 secondary and tertiary structures upon POM binding. These indicate that POM binding involves only local conformational changes in the binding sites. By using intrinsic and 8-anilino-1-naphthalene sulfonate fluorescence titration experiments, we found that POMs bind to S100A9 with a of ca. 2.5 μM. We suggest that the region, including Lys 50 to Lys 54 and characterized by high amyloid propensity, could be the key sequences involved in S1009 amyloid self-assembly. The inhibition and complete hindering of S100A9 amyloid pathways may be used in the therapeutic applications targeting the amyloid-neuroinflammatory cascade in neurodegenerative diseases.
促炎和淀粉样的 S100A9 蛋白是神经退行性疾病中淀粉样神经炎症级联反应的核心。多金属氧酸盐 (POM) 是一组多样化的纳米材料，具有抑制淀粉样蛋白的能力。在这里，我们已经证明了两种选定的纳米铌 POM，Nb 和 TiNb，可以作为 S100A9 淀粉样蛋白聚集的有效抑制剂。基于 ThT 荧光实验的动力学分析表明，添加 Nb 或 TiNb 均可降低 S100A9 淀粉样形成速率和淀粉样蛋白数量。原子力显微镜成像表明，在增加的 POM 浓度下，完全不存在长 S100A9 淀粉样纤维，只有圆形和略微拉长的聚集物。分子动力学模拟表明，Nb 和 TiNb 通过与蛋白质表面带正电荷的 Lys 残基丰富区域形成离子相互作用，结合到天然的 S100A9 同源二聚体上。POM 结合不会干扰 Trp 88 环境，这是通过对固有荧光的丙烯酰胺猝灭来证明的。远和近紫外圆二色性表明，POM 结合不会对 S100A9 的二级和三级结构产生大的扰动。这表明 POM 结合仅涉及结合部位的局部构象变化。通过使用固有和 8-苯胺-1-萘磺酸盐荧光滴定实验，我们发现 POM 与 S100A9 的结合常数约为 2.5 μM。我们认为，包括 Lys 50 到 Lys 54 的区域，具有高淀粉样倾向，可能是涉及 S1009 淀粉样自组装的关键序列。抑制和完全阻止 S100A9 淀粉样途径可用于针对神经退行性疾病中淀粉样神经炎症级联反应的治疗应用。
