The increase in multi-drug resistant pathogenic bacteria is making our current arsenal of clinically used antibiotics obsolete, highlighting the urgent need for new lead compounds with distinct target binding sites to avoid cross-resistance. Here we report that the aromatic polyketide antibiotic tetracenomycin (TcmX) is a potent inhibitor of protein synthesis, and does not induce DNA damage as previously thought. Despite the structural similarity to the well-known translation inhibitor tetracycline, we show that TcmX does not interact with the small ribosomal subunit, but rather binds to the large subunit, within the polypeptide exit tunnel. This previously unappreciated binding site is located adjacent to the macrolide-binding site, where TcmX stacks on the noncanonical basepair formed by U1782 and U2586 of the 23S ribosomal RNA. Although the binding site is distinct from the macrolide antibiotics, our results indicate that like macrolides, TcmX allows translation of short oligopeptides before further translation is blocked.

多重耐药病原菌的增加正在使我们目前临床使用的抗生素库过时，突出表明迫切需要具有不同靶标结合位点的新型先导化合物以避免交叉耐药性。在这里，我们报告芳香族聚酮化合物抗生素四尾霉素 (TcmX) 是一种有效的蛋白质合成抑制剂，并且不会像以前认为的那样诱导 DNA 损伤。尽管与众所周知的翻译抑制剂四环素具有结构相似性，但我们表明 TcmX 不与核糖体小亚基相互作用，而是与多肽出口隧道内的大亚基结合。这个以前未被重视的结合位点位于大环内酯结合位点附近，其中 TcmX 堆叠在由 23S 核糖体 RNA 的 U1782 和 U2586 形成的非规范碱基对上。