Department of Chemistry, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL, USA.
Natural Products Discovery Center, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL, USA.
Nat Chem Biol. 2024 Feb;20(2):243-250. doi: 10.1038/s41589-023-01476-2. Epub 2023 Nov 9.
The anthraquinone-fused enediynes (AFEs) combine an anthraquinone moiety and a ten-membered enediyne core capable of generating a cytotoxic diradical species. AFE cyclization is triggered by opening the F-ring epoxide, which is also the site of the most structural diversity. Previous studies of tiancimycin A, a heavily modified AFE, have revealed a cryptic aldehyde blocking installation of the epoxide, and no unassigned oxidases could be predicted within the tnm biosynthetic gene cluster. Here we identify two consecutively acting cofactorless oxygenases derived from methyltransferase and α/β-hydrolase protein folds, TnmJ and TnmK2, respectively, that are responsible for F-ring tailoring in tiancimycin biosynthesis by comparative genomics. Further biochemical and structural characterizations reveal that the electron-rich AFE anthraquinone moiety assists in catalyzing deformylation, epoxidation and oxidative ring cleavage without exogenous cofactors. These enzymes therefore fill important knowledge gaps for the biosynthesis of this class of molecules and the underappreciated family of cofactorless oxygenases.
蒽醌融合烯二炔（AFE）结合了蒽醌部分和一个十元烯二炔核心，能够产生细胞毒性双自由基物种。AFE 环化是通过打开 F 环环氧化物引发的，这也是结构多样性最大的部位。对天蚕霉素 A 的研究，一种经过大量修饰的 AFE，揭示了隐藏的醛基阻断环氧化物的安装，并且在 tnm 生物合成基因簇中无法预测未分配的氧化酶。在这里，我们通过比较基因组学分别鉴定出两个连续作用的辅因子非依赖性加氧酶，它们分别来自甲基转移酶和 α/β-水解酶蛋白折叠，即 TnmJ 和 TnmK2，负责天蚕霉素生物合成中的 F 环修饰。进一步的生化和结构特征表明，富含电子的 AFE 蒽醌部分有助于在没有外源辅因子的情况下催化脱甲酰基、环氧化和氧化环裂解。这些酶因此填补了此类分子生物合成和未被充分认识的辅因子非依赖性氧化酶家族的重要知识空白。
