Biophysical characterization of p53 core domain aggregates
Biophysical characterization of p53 core domain aggregates
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DOI：
10.1042/bcj20190778
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发表时间：
2020-01-01
影响因子：
4.1
通讯作者：
Cino, Elio A.
中科院分区：
文献类型：
--
作者：
Lima, Igor;Navalkar, Ambuja;Cino, Elio A.
聚集是许多蛋白质构象疾病的原因。这些疾病的一个共同点是蛋白质从其功能性天然状态转变为更高级的形式，如寡聚体和淀粉样纤维。p53是一种基本的肿瘤抑制因子，其易于发生这种构象转变，导致其避免癌症的能力受损。这项工作探讨了早期，中期和晚期阶段的p53核心结构域（p53 C）聚集体的生物物理特性。原子和粗粒度的分子动力学（MD）模拟表明，早期和中期的p53 C聚集体具有反平行和平行的β-片层，本地化的核心淀粉样蛋白序列的多态性拓扑结构。这两种拓扑结构涉及类似程度的链间主链氢键，而侧链相互作用可以发挥作用，在调节链的方向。反平行态和平行态之间的自由能差在统计不确定性范围内。负染电子显微镜的成熟原纤维显示了广泛的分布的纤维宽度，表明多态性可能延伸到四级结构水平。原纤维的圆二色性表明非典型构象中富含β-折叠结构。聚集的p53 C的拉曼光谱与排列的β折叠和异质结构元件的混合物一致，这与两侧为无序结构的有序β折叠核的MD发现一致。结构多态性是淀粉样蛋白的共同特性;然而，由于相同蛋白质的某些多态性可能比其他多晶型更有害，因此今后将有必要建立p53 C聚集体结构与病理学之间的相关性。
Aggregation is the cause of numerous protein conformation diseases. A common facet of these maladies is the transition of a protein from its functional native state into higher order forms, such as oligomers and amyloid fibrils. p53 is an essential tumor suppressor that is prone to such conformational transitions, resulting in its compromised ability to avert cancer. This work explores the biophysical properties of early-, mid-, and late-stage p53 core domain (p53C) aggregates. Atomistic and coarse-grained molecular dynamics (MD) simulations suggest that early- and mid-stage p53C aggregates have a polymorphic topology of antiparallel and parallel beta-sheets that localize to the core amyloidogenic sequence. Both topologies involve similar extents of interstrand mainchain hydrogen bonding, while sidechain interactions could play a role in regulating strand orientation. The free energy difference between the antiparallel and parallel states was within statistical uncertainty. Negative stain electron microscopy of mature fibrils shows a wide distribution of fiber widths, indicating that polymorphism may extend to the quaternary structure level. Circular dichroism of the fibrils was indicative of beta-sheet rich structures in atypical conformations. The Raman spectrum of aggregated p53C was consistent with a mixture of arranged beta-sheets and heterogeneous structural elements, which is compatible with the MD findings of an ordered beta-sheet nucleus flanked by disordered structure. Structural polymorphism is a common property of amyloids; however, because certain polymorphs of the same protein can be more harmful than others, going forward it will be pertinent to establish correlations between p53C aggregate structure and pathology.