Zhang Kaijin, Sun Jingxian, Song Wencai, Liu Junyu, Ma Chuanteng, Chen Yinghan, Guan Yan, Liu Yuting, Ren Zilin, Che Qian, Zhang Guojian, Liu Yankai, Zhu Tianjiao, Li Dehai
Key Laboratory of Marine Drugs, Ministry of Education, Ocean University of China Qingdao 266003 China
Sanya Oceanographic Institute, School of Medicine and Pharmacy, Ocean University of China Sanya 572025 China.
Chem Sci. 2025 May 10. doi: 10.1039/d4sc07174c.
Penicilactam A (1), a fungal alkaloid featuring a rare 5-oxaindolizidine scaffold, has long eluded biosynthetic characterization despite recent advances in microbial genomics. Through retro-biosynthetic analysis of HDN11-186, we identified the gene cluster governing its production. This pathway ultilizes a hybrid polyketide synthase-nonribosomal peptide synthetase (PKS-NRPS) system to assemble the prolinol-containing precursor scalusamide A (2). The multifunctional cytochrome P450 enzyme PnltC then orchestrates two mechanistically distinct reactions: radical-mediated C-C bond cleavage followed by iminium-driven cyclization. Combined structural and computational analyses unveil PnltC's unprecedented catalytic logic, merging radical oxidation with non-radical cyclization within a single active site, which challenges existing paradigms of P450 enzymology. Our findings expand the functional repertoire of oxygenases in natural products (NPs) biosynthesis, revealing nature's sophisticated strategies for constructing complex nitrogen heterocycles.
青霉内酰胺A（1）是一种具有罕见的5-氧杂吲哚嗪骨架的真菌生物碱，尽管微生物基因组学最近取得了进展，但长期以来一直未能对其进行生物合成表征。通过对HDN11-186进行逆向生物合成分析，我们确定了控制其产生的基因簇。该途径利用混合聚酮合酶-非核糖体肽合成酶（PKS-NRPS）系统来组装含脯氨醇的前体斯卡卢酰胺A（2）。多功能细胞色素P450酶PnltC随后协调两个机制不同的反应：自由基介导的C-C键裂解，然后是亚胺驱动的环化。结合结构和计算分析揭示了PnltC前所未有的催化逻辑，即在单个活性位点内将自由基氧化与非自由基环化相结合，这挑战了现有的P450酶学范式。我们的发现扩展了天然产物（NPs）生物合成中氧化酶的功能范围，揭示了自然界构建复杂氮杂环的复杂策略。
