基于代谢组学的蛹虫草菌株虫草素合成途径研究

Biosynthesis pathway of cordycepin in Cordyceps militaris based on metabonomics

通过对蛹虫草菌株代谢组数据分析研究虫草素合成途径,以蛹虫草出发菌株CM08、经过辐射诱变获得的高产虫草素正突变菌株CM09和低产虫草素负突变菌株CM10为研究对象,采用超高效液相色谱-串联飞行时间质谱联用技术测定3个菌株菌丝体的非靶向代谢组数据,并对所得数据进行多元统计分析。主成分分析(principal component analysis,PCA)结果表明,CM08、CM09和CM10的代谢物之间存在显著差异;根据正交偏最小二乘法判别分析(orthogonal partial least squares discrimination analysis,OPLS-DA)模型得到的变量权重值(variable importance for the projection,VIP)区分差异代谢物(VIP﹥1且P﹤0.05),其中CM09 vs CM08差异代谢物64种,CM10 vs CM08差异代谢物147种,主要为氨基酸、糖类与核苷类化合物;KEGG(Kyoto Encyclopedia of Genes and Genomes)代谢通路富集分析发现差异代谢物显著富集到嘌呤代谢途径、磷酸戊糖途径和ABC转运蛋白途径等;差异代谢物腺苷、二磷酸腺苷(adenosine diphosphate,ADP)-核糖、2′-脱氧腺苷、一磷酸腺苷(adenosine monophosphate,AMP)、3′-一磷酸腺苷(adenosine 3′-monophosphate,3′-AMP)和虫草素在正负突变菌株中相对含量上下调相反,说明这些差异代谢物与虫草素产量密切相关,结合已有文献报道完善虫草素合成途径为:ADP-核糖→核糖-5-磷酸→5-磷酸核糖-1-焦磷酸→次黄嘌呤核苷酸→腺苷酸琥珀酸→AMP→腺苷→3′-AMP→2′-羰基-3′-脱氧腺苷→虫草素。该研究为虫草素合成途径的研究提供重要依据。

In this study,the cordycepin biosynthesis pathway was studied by analyzing the metabolome data of Cordyceps militaris strains.The starting strain CM08,the high-yield cordycepin positive mutant strain CM09 and the low-yield cordycepin negative mutant strain CM10 obtained by radiation mutagenesis were studied.The untargeted metabolomics data of CM08,CM09,and CM10 were determine by ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry(UPLC-Q-TOF/MS),and multivariate statistical analysis was conducted.The results of principal component analysis showed that there were significant differences among metabolites of CM08,CM09,and CM10.Differential metabolites were distinguished by variable importance for the projection(VIP)obtained by orthogonal partial least squares discrimination analysis model(VIP>1 and P<0.05),and there were 64 differential metabolites of CM09 vs CM08 and 147 differential metabolites of CM10 vs CM08,including amino acids,saccharides and nucleoside compounds.Enrichment analysis of Kyoto Encyclopedia of Genes and Genomes(KEGG)metabolic pathways showed that differential metabolites were significantly enriched in purine metabolic pathway,pentose phosphate pathway and ABC transporter pathway.The relative contents down-regulated and up-regulated of enriched differential metabolites adenosine,ADP-ribose,2′-deoxyadenosine,adenosine monophosphate(AMP),3′-AMP and cordycepin were reversed in positive and negative mutant strains,which showed that these differential metabolites were closely related to the yield of cordycepin,Combined with literature reports and the results of this study,the biosynthesis pathway of cordycepin is speculated as follows:ADP-Ribose→Ribose-5-P→PRPP→IMP→Adenylosuccinate→AMP→Adenosine→3′-AMP→2′-C-3′-dA→cordycepin,which provides important basis for the study of cordycepin biosynthesis pathway.