Synthetic RNA-based gene circuits enable sophisticated gene regulation without the risk of insertional mutagenesis. While various RNA binding proteins have been used for translational repression in gene circuits, the direct translational activation of synthetic mRNAs has not been achieved. Here we develop Caliciviral VPg-based Translational activator (CaVT), which activates the translation of synthetic mRNAs without the canonical 5′-cap. The level of translation can be modulated by changing the locations, sequences, and modified nucleosides of CaVT-binding motifs in the target mRNAs, enabling the simultaneous translational activation and repression of different mRNAs with RNA-only delivery. We demonstrate the efficient regulation of apoptosis and genome editing by tuning translation levels with CaVT. In addition, we design programmable CaVT that responds to endogenous microRNAs or small molecules, achieving both cell-state-specific and conditional translational activation from synthetic mRNAs. CaVT will become an important tool in synthetic biology for both biological studies and future therapeutic applications.

基于合成RNA的基因电路可进行复杂的基因调节，而不会发生插入诱变的风险。尽管各种RNA结合蛋白已用于基因回路中的翻译抑制，但合成mRNA的直接翻译激活尚未实现。在这里，我们开发了基于杯状病毒VPg的翻译激活剂（CaVT），该激活剂可激活合成的mRNA的翻译而无需规范的5'-cap。可以通过改变目标mRNA中CaVT结合基序的位置，序列和修饰的核苷来调节翻译水平，从而能够通过仅RNA递送同时翻译激活和抑制不同的mRNA。我们展示了通过调节CaVT的翻译水平来有效调控细胞凋亡和基因组编辑。此外，我们设计了可编程的CaVT，可响应内源性microRNA或小分子，从合成的mRNA中实现细胞状态特异性和条件翻译激活。CaVT将成为生物学研究和未来治疗应用中合成生物学的重要工具。