Zika virus (ZIKV) infection remains a worldwide concern, and currently, no effective treatments or vaccines are available. Novel therapeutics are an avenue of interest that could probe viral RNA-human protein communication to stop viral replication. One specific RNA structure, G-quadruplexes (G4s), possess various roles in viruses and all domains of life, including transcription and translation regulation, genome stability, and serving as nucleation points for RNA liquid-liquid phase separation. Previous G4 studies on ZIKV using a Quadruplex forming G-Rich Sequences (QGRS) Mapper located a potential G-quadruplex sequence (PQS) in the 3' terminal region (TR) and was validated structurally using a 25-mer oligo. It is currently unknown if this structure is conserved and maintained in a large ZIKV RNA transcript, and its specific roles in viral replication. Using bioinformatic analysis and biochemical assays, we demonstrate that the ZIKV 3' TR G4 is conserved across all ZIKV isolates and maintains its structure in a 3' TR full-length transcript. We further established the G4 formation using Pyridostatin (PDS) and the BG4 G4-recognizing antibody binding assays. Our work also demonstrates that the human DEAD-box helicases, DDX3X132-607 and DDX17135-555, bind to the 3' TR, and that DDX17135-555 unfolds the G4 present in the 3' TR. These findings provide a path forward in potential therapeutic targeting of DDX3X or DDX17's binding to the 3' TR G4 region for novel treatments against ZIKV.

中文翻译：

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寨卡病毒 RNA 的 3' 末端区域包含保守的 G-四链体，并由人 DDX17 解折叠。

寨卡病毒（ZIKV）感染仍然是全世界关注的问题，目前尚无有效的治疗方法或疫苗。新型疗法是一种令人感兴趣的途径，可以探测病毒 RNA 与人类蛋白质的通讯，从而阻止病毒复制。G-四链体 (G4) 是一种特定的 RNA 结构，在病毒和生命的所有领域中具有多种作用，包括转录和翻译调节、基因组稳定性以及作为 RNA 液-液相分离的成核点。之前使用四链体形成 G 丰富序列 (QGRS) 映射器对 ZIKV 进行的 G4 研究在 3' 末端区域 (TR) 定位了潜在的 G 四链体序列 (PQS)，并使用 25 聚体寡核苷酸进行了结构验证。目前尚不清楚该结构是否在 ZIKV RNA 转录本中保守并维持，以及它在病毒复制中的具体作用。通过生物信息学分析和生化测定，我们证明 ZIKV 3'TR G4 在所有 ZIKV 分离株中都是保守的，并在 3'TR 全长转录物中保持其结构。我们使用吡啶抑素 (PDS) 和 BG4 G4 识别抗体结合测定进一步确定了 G4 形成。我们的工作还表明，人类 DEAD-box 解旋酶 DDX3X132-607 和 DDX17135-555 与 3' TR 结合，并且 DDX17135-555 解折叠 3' TR 中存在的 G4。这些发现为 DDX3X 或 DDX17 与 3' TR G4 区域结合的潜在治疗靶向提供了一条针对 ZIKV 的新型治疗方法。