Alferova Vera A, Baranova Anna A, Belozerova Olga A, Gulyak Evgeny L, Mikhaylov Andrey A, Solovev Yaroslav V, Zhitlov Mikhail Y, Sinichich Arseniy A, Tyurin Anton P, Trusova Ekaterina A, Beletsky Alexey V, Mardanov Andrey V, Ravin Nikolai V, Lapchinskaya Olda A, Korshun Vladimir A, Gabibov Alexander G, Terekhov Stanislav S
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, Moscow 117997, Russia.
Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russia.
Antibiotics (Basel). 2024 Dec 3;13(12):1167. doi: 10.3390/antibiotics13121167.
Irumamycin (Iru) is a complex polyketide with pronounced antifungal activity produced by a type I polyketide (PKS) synthase. Iru features a unique hemiketal ring and an epoxide group, making its biosynthesis and the structural diversity of related compounds particularly intriguing. In this study, we performed a detailed analysis of the biosynthetic gene cluster (BGC) to uncover the mechanisms underlying Iru formation. We examined the PKS, including the domain architecture of individual modules and the overall spatial structure of the PKS, and uncovered discrepancies in substrate specificity and iterative chain elongation. Two potential pathways for the formation of the hemiketal ring, involving either an olefin shift or electrocyclization, were proposed and assessed using O-labeling experiments and reaction activation energy calculations. Based on our findings, the hemiketal ring is likely formed by PKS-assisted double bond migration and TE domain-mediated cyclization. Furthermore, putative tailoring enzymes mediating epoxide formation specific to Iru were identified. The revealed Iru biosynthetic machinery provides insight into the complex enzymatic processes involved in Iru production, including macrocycle sculpting and decoration. These mechanistic details open new avenues for a targeted architecture of novel macrolide analogs through synthetic biology and biosynthetic engineering.
伊鲁霉素（Iru）是一种由I型聚酮合酶（PKS）产生的具有显著抗真菌活性的复杂聚酮化合物。Iru具有独特的半缩酮环和环氧基团，这使得其生物合成以及相关化合物的结构多样性特别引人关注。在本研究中，我们对生物合成基因簇（BGC）进行了详细分析，以揭示Iru形成的潜在机制。我们研究了聚酮合酶，包括各个模块的结构域架构以及聚酮合酶的整体空间结构，并发现了底物特异性和迭代链延伸方面的差异。我们提出了两种形成半缩酮环的潜在途径，涉及烯烃迁移或电环化，并通过O标记实验和反应活化能计算进行了评估。基于我们的研究结果，半缩酮环可能是由聚酮合酶辅助的双键迁移和硫酯酶（TE）结构域介导的环化形成的。此外，还鉴定了介导Iru特异性环氧形成的推定修饰酶。所揭示的Iru生物合成机制为深入了解Iru生产过程中涉及的复杂酶促过程提供了线索，包括大环塑造和修饰。这些机制细节为通过合成生物学和生物合成工程有针对性地构建新型大环内酯类似物开辟了新途径。
