珊瑚来源真菌Parengyodontium album SCSIO SX7W11中聚酮化合物的发现及其生物合成途径分析

Discovery of polyketide natural products from corals derived fungi Parengyodontium album SCSIO SX7W11 and their biosynthetic pathway analysis

摘要:

海洋来源真菌的天然产物因其独特的结构与生物学活性而备受关注，而利用基因组信息对其代谢产物进行深入挖掘也成为研究策略之一。[目的] 本文以一株南海珊瑚来源的真菌Parengyodontium album SCSIO SX7W11为目标菌株，挖掘其生产聚酮类化合物的潜能。[方法] 本研究利用Illumina Miseq技术对SX7W11菌株进行全基因组扫描测序，运用生物信息学手段对其基因组的生物合成基因簇进行预测和基因功能注释，挖掘可能产生新颖聚酮化合物的基因簇。对SX7W11进行放大发酵后，利用正相色谱、中压反相色谱、Sephadex LH-20凝胶色谱、HPLC半制备等分离手段分离纯化出单体化合物。再利用高分辨质谱（HR-ESI-MS）、¹H NMR、¹³C NMR、X-ray单晶衍射等波谱手段确定化合物的结构，并根据生物合成基因簇对化合物的生物合成途径进行推导。[结果] 全基因组扫描测序结果显示，P.album SCSIO SX7W11基因组大小为34.0 Mb，含有24个生物合成基因簇，包括6个聚酮合酶基因簇以及3个萜烯合酶基因簇。从发酵产物中分离鉴定到3个聚酮类化合物：emodin（1）、alternaphenol B（2）和sydowinin A（3），其中化合物3获得了单晶结构数据。通过生物信息学方法从菌株基因组中定位到了sydowinin A的生物合成基因簇。结合文献对emodin（1）、alternaphenol B（2）和sydowinin A（3）的生物合成途径进行了分析。[结论] 本研究通过基因组挖掘及培养基优化，发现1株珊瑚来源的真菌P.album SCSIO SX7W11具有生产sydowinins类聚酮类化合物的能力，为该类化合物生物合成机制深入研究奠定了基础。

Abstract:

Natural products from marine fungi have been attracting attention for their unique structures and biological activities. Genome mining has become an emerging strategy to explore their metabolites. [Objective] In this study, we investigated Parengyodontium album SCSIO SX7W11, a marine fungus derived from South China Sea corals for the potential of producing polyketides. [Methods] We sequenced the whole genome of strain SX7W11 using Illumina Miseq. The polyketide biosynthetic gene clusters were then predicted and the functions of open reading frames (ORFs) were annotated. Normal phase chromatography, reversed-phase chromatography, Sephadex LH-20 chromatography, and High Performance Liquid Chromatography (HPLC) were conducted for the isolation and purification of natural products. The purified compounds were characterized by high resolution mass spectrometry (HR-ESI-MS), ¹H NMR, ¹³C NMR and X-ray data and the biosynthetic pathways were deduced. [Results] The whole genome scanning and sequencing results showed that the genome length of SX7W11 is 34.0 Mb, containing 24 biosynthetic gene clusters. Three polyketides were identified as emodin (1), alternaphenol B (2), and sydowinin A (3). The crystal data of sydowinin A was obtained. The biosynthetic gene cluster of sydowinin A was localized from SX7W11 genome by bioinformatics analysis. The biosynthetic pathway was then proposed. [Conclusion] Through genome mining and medium optimization, P. album SCSIO SX7W11, a coral derived fungus, has shown the potential to produce sydowinin type polyketides. This work laid a foundation for the biosynthesis study of sydowinin.