Abstract
The translation of messenger RNA (mRNA) is a fundamental process in gene expression, and control of translation is important to regulate protein synthesis in cells. The primary hallmark of eukaryotic mRNAs is their 5' cap, whose molecular contacts to the eukaryotic translation initiation factor eIF4E govern the initiation of translation. Here we report 5' cap analogues with photo-cleavable groups (FlashCaps) that prohibit binding to eIF4E and resist cleavage by decapping enzymes. These compounds are compatible with the general and efficient production of mRNAs by in vitro transcription. In FlashCap-mRNAs, the single photocaging group abrogates translation in vitro and in mammalian cells without increasing immunogenicity. Irradiation restores the native cap, triggering efficient translation. FlashCaps overcome the problem of remaining sequence or structure changes in mRNA after irradiation that limited previous designs. Together, these results demonstrate that FlashCaps offer a route to regulate the expression of any given mRNA and to dose mRNA therapeutics with spatio-temporal control.