Multienzyme-Mediated Atypical Mode of Dehydration in Anthracycline Biosynthesis

作者：Yi Shuang Wang, Hongwei Chen, Zi Kang Meng, Chen Jia, Jiaqi Han, Yun Xia Jin, Xiuxiu Ma, Nanxi Wang, Jiapeng Zhu, Yong Liang, Ren Xiang Tan · 发表于：ACS Catalysis · 年份：2025 · DOI：10.1021/acscatal.5c06208 · 被引用次数：2 · 研究领域：Microbial Natural Products and Biosynthesis、Enzyme Structure and Function、DNA Repair Mechanisms

Anthracyclines featuring a tetracyclic (A–D rings) scaffold, such as clinically approved doxorubicin and aclarubicin, are essential natural products. The D-ring presents an intriguing structural puzzle: while predominantly nonaromatic and typically decorated with one or two α-oriented oxygenated substituents, its aromatization constitutes a critical biosynthetic prerequisite for the conversion of resomycin C into chartreusin, a promising antitumor drug candidate. Given the intriguing and biologically significant nature of the “D-ring state”, we elucidate here the mechanism of D-ring aromatization during resomycin C biosynthesis. This process features an unprecedented dehydration pattern mediated by the collaborative catalysis of two enzymes, ChaU and ChaX. Combining gene inactivation, biochemical assays, isotope labeling, protein crystallography, and site-directed mutagenesis, we demonstrated that ChaU facilitates the stereoselective C2–C19 cyclization and plays a critical role in prompting the attack of water on C17 from the pro-R face, followed by the 17-dehydroxylation mediated by ChaX, thereby triggering the aromatization of the D-ring. Furthermore, molecular dynamics simulations and density functional theory calculations elucidated the stepwise catalytic mechanism of the ChaU/ChaX-mediated cascade reactions that drive D-ring aromatization, uncovering a previously unrecognized dehydration pathway. Collectively, this work reveals sophisticated enzymatic strategies for anth...