Unusual and Highly Bioactive Sesterterpenes Synthesized by Pleurotus ostreatus during Coculture with Trametes robiniophila Murr
Unusual and Highly Bioactive Sesterterpenes Synthesized by Pleurotus ostreatus during Coculture with Trametes robiniophila Murr
复制标题
平菇与栓菌共培养期间合成的异常且高生物活性的二萜
DOI：
10.1128/aem.00293-19
复制
发表时间：
2019
影响因子：
4.4
通讯作者：
Song Yang
中科院分区：
文献类型：
--
作者：
Xiao-Ting Shen;Xu-Hua Mo;Li-Ping Zhu;Ling-Ling Tan;Feng-Yu Du;Qian-Wen Wang;Yuan-Ming Zhou;Xiao-Jie Yuan;Bin Qiao;Song Yang
许多参与次生代谢物生物合成的基因簇在标准实验室培养条件下可能是沉默的或以低水平表达，导致所发现的代谢物库与基因组能力之间存在很大差距。本工作通过构建人工共培养的担子菌真菌来模拟天然存在的竞争，以鉴定具有新型支架和优异生物活性的次级代谢产物。糙皮侧耳合成的不寻常的postrediene A到C的线性二倍半萜不仅是有希望的抗人类病原真菌的先导药物，而且还突出了担子菌中二倍半萜生物合成的独特途径。目前的工作提供了一个重要的基础，揭示新的基因功能参与二倍半萜合成和获得洞察沉默基因激活机制的真菌防御。摘要白色念珠菌和新型隐球菌是世界范围内常见的人类致病真菌，由于其在免疫功能低下患者中的高发病率和高死亡率而受到越来越多的关注。通过对16种木材腐朽菌进行共培养，构建了110个真菌对，其中槐栓菌（Trametes robiniophila）穆尔（Murr）与糙皮侧耳（Pleumatostreatus）共培养对木材腐朽菌具有较强的抑制作用。代谢组学和分子网络分析的组合显示，44个特征是新合成的或在该共培养系统中以高水平产生的，并且其中6个特征属于新颖且不寻常的线性二倍半萜家族，其对病原真菌的MIC为1至32 μg/ml。此外，动态13 C-标记分析揭示了诱导功能和相应的真菌之间的关联。在共培养刺激后的一个时间过程中，不寻常的二萜类化合物仅在糙皮侧耳中被13 C标记，表明这些二萜类化合物是由糙皮侧耳合成的，而不是由T.槐属穆尔二倍半萜化合物1至3被重新命名为后二烯A至C。实时逆转录-定量PCR（RT-qPCR）分析显示，编码萜烯合酶、法呢基-二磷酸法呢基转移酶和氧化酶的三个基因的转录水平在共培养物中分别比在单培养物中高8.2倍、88.7倍和21.6倍，表明生物合成基因簇10最可能负责这些二倍半萜的合成。基于二倍半萜的结构和分子网络分析，提出了一条推测的后二烯A到后二烯C的生物合成途径。重要性在标准实验室培养条件下，参与次级代谢物生物合成的许多基因簇可能是沉默的或以低水平表达，导致发现的代谢物库与基因组能力之间存在很大差距。本工作通过构建人工共培养的担子菌真菌来模拟天然存在的竞争，以鉴定具有新型支架和优异生物活性的次级代谢产物。糙皮侧耳合成的不寻常的postrediene A到C的线性二倍半萜不仅是有希望的抗人类病原真菌的先导药物，而且还突出了担子菌中二倍半萜生物合成的独特途径。目前的工作提供了一个重要的基础，揭示新的基因功能参与二倍半萜合成和获得洞察沉默基因激活机制的真菌防御。
A number of gene clusters involved in biosynthesis of secondary metabolites are presumably silent or expressed at low levels under conditions of standard laboratory cultivation, resulting in a large gap between the pool of discovered metabolites and genome capability. This work mimicked naturally occurring competition by construction of an artificial coculture of basidiomycete fungi for the identification of secondary metabolites with novel scaffolds and excellent bioactivity. Unusual linear sesterterpenes of postrediene A to C synthesized by P. ostreatus not only were promising lead drugs against human-pathogenic fungi but also highlighted a distinct pathway for sesterterpene biosynthesis in basidiomycetes. The current work provides an important basis for uncovering novel gene functions involved in sesterterpene synthesis and for gaining insights into the mechanism of silent gene activation in fungal defense. ABSTRACT Candida albicans and Cryptococcus neoformans, human-pathogenic fungi found worldwide, are receiving increasing attention due to high morbidity and mortality in immunocompromised patients. In the present work, 110 fungus pairs were constructed by coculturing 16 wood-decaying basidiomycetes, among which coculture of Trametes robiniophila Murr and Pleurotus ostreatus was found to strongly inhibit pathogenic fungi through bioactivity-guided assays. A combination of metabolomics and molecular network analysis revealed that 44 features were either newly synthesized or produced at high levels in this coculture system and that 6 of the features that belonged to a family of novel and unusual linear sesterterpenes contributed to high activity with MICs of 1 to 32 μg/ml against pathogenic fungi. Furthermore, dynamic 13C-labeling analysis revealed an association between induced features and the corresponding fungi. Unusual sesterterpenes were 13C labeled only in P. ostreatus in a time course after stimulation by the coculture, suggesting that these sesterterpenes were synthesized by P. ostreatus instead of T. robiniophila Murr. Sesterterpene compounds 1 to 3 were renamed postrediene A to C. Real-time reverse transcription-quantitative PCR (RT-qPCR) analysis revealed that transcriptional levels of three genes encoding terpene synthase, farnesyl-diphosphate farnesyltransferase, and oxidase were found to be 8.2-fold, 88.7-fold, and 21.6-fold higher, respectively, in the coculture than in the monoculture, indicating that biosynthetic gene cluster 10 was most likely responsible for the synthesis of these sesterterpenes. A putative biosynthetic pathway of postrediene A to postrediene C was then proposed based on structures of sesterterpenes and molecular network analysis. IMPORTANCE A number of gene clusters involved in biosynthesis of secondary metabolites are presumably silent or expressed at low levels under conditions of standard laboratory cultivation, resulting in a large gap between the pool of discovered metabolites and genome capability. This work mimicked naturally occurring competition by construction of an artificial coculture of basidiomycete fungi for the identification of secondary metabolites with novel scaffolds and excellent bioactivity. Unusual linear sesterterpenes of postrediene A to C synthesized by P. ostreatus not only were promising lead drugs against human-pathogenic fungi but also highlighted a distinct pathway for sesterterpene biosynthesis in basidiomycetes. The current work provides an important basis for uncovering novel gene functions involved in sesterterpene synthesis and for gaining insights into the mechanism of silent gene activation in fungal defense.