A Nonfunctional Halogenase Masquerades as an Aromatizing Dehydratase in Biosynthesis of Pyrrolic Polyketides by Type I Polyketide Synthases
A Nonfunctional Halogenase Masquerades as an Aromatizing Dehydratase in Biosynthesis of Pyrrolic Polyketides by Type I Polyketide Synthases
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DOI：
10.1021/acschembio.2c00288
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发表时间：
2022-06-17
影响因子：
4
通讯作者：
Agarwal, Vinayak
中科院分区：
文献类型：
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作者：
Yi, Dongqi;Niroula, Dhirendra;Agarwal, Vinayak
细菌模块 I 型聚酮合酶 (PKS) 通常提供非芳香族内酯和内酰胺天然产物。在这里，通过完整的体外酶促生产聚酮类抗生素幽门螺杆菌素，我们描述了通过 I 型 PKS 构建芳香间苯二酚环的生物合成机制。我们发现，I 型幽门螺杆菌素 PKS 不会产生芳香产物，而是提供脂环族二氢间苯三酚，随后进行酶脱水和芳香化。芳香化脱水酶在幽门螺杆菌素生物合成基因簇 (BGC) 中编码，并且其存在在编码吡咯聚酮化合物生产的其他 BGC 中是保守的。序列相似性和突变分析表明，芳香化脱水酶活性位点的整体结构和位置与黄素依赖性卤化酶相同，尽管失去了进行氧化还原催化的能力。我们证明 PKS 后脱水芳构化对于幽门螺杆菌的抗生素活性至关重要。
The bacterial modular type I polyketide synthases (PKSs) typically furnish nonaromatic lactone and lactam natural products. Here, by the complete in vitro enzymatic production of the polyketide antibiotic pyoluteorin, we describe the biosynthetic mechanism for the construction of an aromatic resorcylic ring by a type I PKS. We find that the pyoluteorin type I PKS does not produce an aromatic product, rather furnishing an alicyclic dihydrophloroglucinol that is later enzymatically dehydrated and aromatized. The aromatizing dehydratase is encoded in the pyoluteorin biosynthetic gene cluster (BGC), and its presence is conserved in other BGCs encoding production of pyrrolic polyketides. Sequence similarity and mutational analysis demonstrates that the overall structure and position of the active site for the aromatizing dehydratase is shared with flavin-dependent halogenases albeit with a loss in ability to perform redox catalysis. We demonstrate that the post-PKS dehydrative aromatization is critical for the antibiotic activity of pyoluteorin.