SRA

Small molecule compounds that sense the nucleic acid sequences, promise the attractive venue for drug development. Such an unusual effect has been observed in the natural product Rocaglamide A (RocA) from Aglaia plant, proving to exhibit anti-tumor effects by clamping eukaryotic initiation factor (eIF) 4A onto mRNA polypurine sequences. Although eIF4A has been speculated the unique target of RocA, the insensitization of eIF4A in human cells only partially rescued the translation repression from RocA, suggesting another alternative target of this compound. Here, we revealed that DDX3 is an alternative target of RocA. Developing a RocA derivative with an O-nitrobenzoxadiazole unit (RocA-O-NBD), which can covalently bind to proximate proteins and provide fluorescence to them, we identified DDX3 bound to RocA. As observed in eIF4A, RocA locked the DDX3 protein onto polypurine sequences of RNA in an ATP-independent manner. De novo assembled Aglaia plant transcriptome uncovered the natural amino acid substitutions in Aglaia DDX3 to protect itself from RocA toxicity. Because of the dominant negative effect of RocA, we also proved the protein abundance of eIF4A and DDX3 in cancer cells determines their sensitivity to RocA. Overall, this study discovered DDX3 as another target of RocA and suggests the probability to predict tumor toxicity of RocA by the target abundance. Overall design: Ribosome profiling