Department of Microbiology and Molecular Genetics, University of California, Davis, California, United States of America.
Department of Chemical Engineering, University of California, Davis, California, United States of America.
PLoS Pathog. 2021 Nov 19;17(11):e1010100. doi: 10.1371/journal.ppat.1010100. eCollection 2021 Nov.
Dengue virus (DENV) disruption of the innate immune response is critical to establish infection. DENV non-structural protein 5 (NS5) plays a central role in this disruption, such as antagonism of STAT2. We recently found that DENV serotype 2 (DENV2) NS5 interacts with Polymerase associated factor 1 complex (PAF1C). The primary members of PAF1C are PAF1, LEO1, CTR9, and CDC73. This nuclear complex is an emerging player in the immune response. It promotes the expression of many genes, including genes related to the antiviral, antimicrobial and inflammatory responses, through close association with the chromatin of these genes. Our previous work demonstrated that NS5 antagonizes PAF1C recruitment to immune response genes. However, it remains unknown if NS5 antagonism of PAF1C is complementary to its antagonism of STAT2. Here, we show that knockout of PAF1 enhances DENV2 infectious virion production. By comparing gene expression profiles in PAF1 and STAT2 knockout cells, we find that PAF1 is necessary to express immune response genes that are STAT2-independent. Finally, we mapped the viral determinants for the NS5-PAF1C protein interaction. We found that NS5 nuclear localization and the C-terminal region of the methyltransferase domain are required for its interaction with PAF1C. Mutation of these regions rescued the expression of PAF1-dependent immune response genes that are antagonized by NS5. In sum, our results support a role for PAF1C in restricting DENV2 replication that NS5 antagonizes through its protein interaction with PAF1C.
登革热病毒（DENV）破坏先天免疫反应对于建立感染至关重要。DENV 非结构蛋白 5（NS5）在这种破坏中发挥核心作用，例如拮抗 STAT2。我们最近发现，DENV 血清型 2（DENV2）NS5 与聚合酶相关因子 1 复合物（PAF1C）相互作用。PAF1C 的主要成员是 PAF1、LEO1、CTR9 和 CDC73。这个核复合物是免疫反应中的新兴参与者。它通过与这些基因的染色质密切结合，促进许多基因的表达，包括与抗病毒、抗菌和炎症反应相关的基因。我们之前的工作表明，NS5 拮抗 PAF1C 募集到免疫反应基因。然而，NS5 对 PAF1C 的拮抗作用是否与其对 STAT2 的拮抗作用互补仍不清楚。在这里，我们显示敲除 PAF1 可增强 DENV2 感染性病毒粒子的产生。通过比较 PAF1 和 STAT2 敲除细胞中的基因表达谱，我们发现 PAF1 是表达与 STAT2 无关的免疫反应基因所必需的。最后，我们绘制了 NS5-PAF1C 蛋白相互作用的病毒决定因素图谱。我们发现 NS5 的核定位和甲基转移酶结构域的 C 末端区域是其与 PAF1C 相互作用所必需的。这些区域的突变挽救了 NS5 拮抗的依赖于 PAF1C 的免疫反应基因的表达。总之，我们的结果支持 PAF1C 在限制 DENV2 复制中的作用，而 NS5 通过与 PAF1C 的蛋白相互作用拮抗该作用。
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