Tetracyclines Modify Translation by Targeting Key Human rRNA Substructures

Apart from their antimicrobial properties, tetracyclines demonstrate clinically validated effects in the amelioration of pathological inflammation and human cancer. Delineation of the target(s) and mechanism(s) responsible for these effects, however, has remained elusive. Here, employing quantitative mass spectrometry-based proteomics, we identified human 80S ribosomes as targets of the tetracyclines Col-3 and doxycycline. We then developed in-cell click selective crosslinking with RNA sequence profiling (icCL-seq) to map binding sites for these tetracyclines on key human rRNA substructures at nucleotide resolution. Importantly, we found that structurally and phenotypically variant tetracycline analogs could chemically discriminate these rRNA binding sites. We also found that tetracyclines both subtly modify human ribosomal translation and selectively activate the cellular integrated stress response (ISR). Together, the data reveal that targeting of specific rRNA substructures, activation of the ISR, and inhibition of translation are correlated with the anti-proliferative properties of tetracyclines in human cancer cell lines. [Display omitted] •Tetracycline analogs Col-3 and doxycycline target the human ribosome•Tetracyclines' human ribosomal binding sites map to unique rRNA substructures•Ribosomal targeting strongly correlates with tetracyclines' anti-proliferative activity•Col-3 and doxycycline directly inhibit human ribosomal translation Mortison et al. identified the human ribosome as a target of the tetracycline analogs Col-3 and doxycycline and mapped the binding sites for these tetracyclines to unique rRNA substructures. The authors show that Col-3 and doxycycline inhibit human ribosomal translation and activate the cellular integrated stress response.