RNA-Seq of A375 cells treated with tetracycline-based crosslinking probes to identify binding sites for the tetracycline analogs Col-3 and doxycycline on the human ribosome

Following the identification of the 80S ribosome as a putative target of the tetracycline analogs Col3 and doxycycline, we next sought to identify the precise binding sites for these tetracyclines within the ribonucleoprotein complex. We incorporated dual bioorthogonal handles into tetracycline-based probes, containing both a photoactive diazirine to enable direct probe crosslinking to the human ribosome and an azide handle to allow selective enrichment of crosslinked biomolecules via copper-free click chemistry. The Col-3 and doxycycline probes were each incubated with A375 cells, followed by irradiation at 365 nm to induce photolysis of the diazirine moiety and subsequent crosslinking to adjacent ribosomal components. Pulldown and RNA-Seq of the crosslinked RNAs from our experiments were used to identify enrichment of reverse transcription (RT) stops at ribosomal RNA sites caused by local crosslinking of our probes. This RNA-Seq based RT stop enrichment analysis was compared to results using an non-specific aniline control probe and untreated controls.