Molecular Biotechnology, Leiden University, PO Box 9505, 2300RA Leiden, The Netherlands.
State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, Shandong 266237, P. R. China.
ACS Chem Biol. 2020 Sep 18;15(9):2529-2538. doi: 10.1021/acschembio.0c00564. Epub 2020 Sep 8.
Angucyclines are a structurally diverse class of actinobacterial natural products defined by their varied polycyclic ring systems, which display a wide range of biological activities. We recently discovered lugdunomycin (), a highly rearranged polyketide antibiotic derived from the angucycline backbone that is synthesized via several yet unexplained enzymatic reactions. Here, we show via , , and structural analysis that the promiscuous reductase LugOII catalyzes both a C6 and an unprecedented C1 ketoreduction. This then sets the stage for the subsequent C-ring cleavage that is key to the rearranged scaffolds of . The 1.1 Å structures of LugOII in complex with either ligand 8--Methylrabelomycin () or 8--Methyltetrangomycin () and of apoenzyme were resolved, which revealed a canonical Rossman fold and a remarkable conformational change during substrate capture and release. Mutational analysis uncovered key residues for substrate access, position, and catalysis as well as specific determinants that control its dual functionality. The insights obtained in this work hold promise for the discovery and engineering of other promiscuous reductases that may be harnessed for the generation of novel biocatalysts for chemoenzymatic applications.
安格鲁霉素是一类结构多样的放线菌天然产物，其特征为多变的多环体系，具有广泛的生物活性。我们最近发现了 lugdunomycin（），这是一种高度重排的聚酮类抗生素，来源于 angucycline 骨架，通过几个尚未解释的酶促反应合成。在这里，我们通过 X 射线晶体学、化学和结构分析表明，多功能还原酶 LugOII 催化 C6 和前所未有的 C1 酮还原。这为随后的 C 环裂解奠定了基础，C 环裂解是重排支架的关键。解析了 LugOII 与配体 8--Methylrabelomycin（）或 8--Methyltetrangomycin（）复合物和apoenzyme 的 1.1 Å 结构，揭示了一个典型的 Rossman 折叠和在底物捕获和释放过程中的显著构象变化。突变分析揭示了关键的底物进入、定位和催化残基以及控制其双重功能的特定决定因素。这项工作中的见解为发现和工程化其他多功能还原酶提供了希望，这些还原酶可能被用于生成用于化学酶应用的新型生物催化剂。
