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Abstract：
Viruses form extensive interfaces with host proteins to modulate the biology of the infected cell, frequently via multifunctional viral proteins. These proteins are conventionally considered as assemblies of independent functional modules, where the presence or absence of modules determines the overall composite phenotype. However, this model cannot account for functions observed in specific viral proteins. For example, rabies virus (RABV) P3 protein is a truncated form of the pathogenicity factor P protein, but displays a unique phenotype with functions not seen in longer isoforms, indicating that changes beyond the simple complement of functional modules define the functions of P3. Here, we report structural and cellular analyses of P3 derived from the pathogenic RABV strain Nishigahara (Nish) and an attenuated derivative strain (Ni-CE). We identify a network of intraprotomer interactions involving the globular C-terminal domain and intrinsically disordered regions (IDRs) of the N-terminal region that characterize the fully functional Nish P3 to fluctuate between open and closed states, whereas the defective Ni-CE P3 is predominantly open. This conformational difference appears to be due to the single mutation N226H in Ni-CE P3. We find that Nish P3, but not Ni-CE or N226H P3, undergoes liquid-liquid phase separation and this property correlates with the capacity of P3 to interact with different cellular membrane-less organelles, including those associated with immune evasion and pathogenesis. Our analyses propose that discrete functions of a critical multifunctional viral protein depend on the conformational arrangements of distant individual domains and IDRs, in addition to their independent functions.
摘要：
病毒与宿主蛋白形成广泛的界面来调节被感染细胞的生物学，经常通过多功能病毒蛋白。这些蛋白质通常被认为是独立的功能模块的集合。其中模块的存在或不存在决定了整体复合表型。然而,该模型不能解释在特定病毒蛋白中观察到的功能。例如,狂犬病病毒(RABV)P3蛋白是致病因子P蛋白的截短形式,但表现出一种独特的表型，其功能在较长的同种型中看不到，表明超出功能模块简单补充的变化定义了P3的功能。这里,我们报告了来自致病性RABV菌株Nishigahara（Nish）和减毒衍生菌株（Ni-CE）的P3的结构和细胞分析。我们确定了涉及球形C末端结构域和N末端区域的固有无序区域（IDR）的内质子相互作用网络，这些区域表征了全功能NishP3在开放状态和封闭状态之间波动，而有缺陷的Ni-CEP3主要是开放的。这种构象差异似乎是由于Ni-CEP3中的单突变N226H。我们发现NishP3，而不是Ni-CE或N226HP3，经历液-液相分离，这种性质与P3与不同的无细胞膜细胞器相互作用的能力相关，包括与免疫逃避和发病机制有关的那些。我们的分析表明，关键的多功能病毒蛋白的离散功能取决于远处的单个结构域和IDR的构象排列，除了它们的独立功能。
