蛹虫草磷酸甲羟戊酸激酶和焦磷酸甲羟戊酸脱羧酶基因的功能分析

Functions of genes encoding phosphomevalonate kinase and mevalonate diphosphate decarboxylase in Cordyceps militaris

摘要:

【目的】确定蛹虫草甲羟戊酸途径中的2个关键酶——磷酸甲羟戊酸激酶（CmErg8）和焦磷酸甲羟戊酸脱羧酶（CmErg19）的功能及其对麦角甾醇和虫草素含量的影响。【方法】通过生物信息学分析鉴定蛹虫草中CmErg8和CmErg19，并采用酵母互补确定其功能是否保守；以蛹虫草尿嘧啶营养缺陷型CmΔpyrG为背景菌株，利用农杆菌介导的转化方法对CmErg8和CmErg19进行过表达，观察其对麦角甾醇和虫草素含量的影响。【结果】CmErg8和CmErg19不能互补酵母erg8和erg19突变体的温度敏感表型；CmErg8和CmErg19过表达菌株中麦角甾醇和虫草素含量均有所增加，特别是CmErg19基因过表达可以使虫草素含量提升5倍左右。【结论】本研究揭示了蛹虫草CmErg8和CmErg19的功能，并且发现蛹虫草麦角甾醇合成通路基因可能会影响虫草素含量。

关键词:蛹虫草;磷酸甲羟戊酸激酶;焦磷酸甲羟戊酸脱羧酶;麦角甾醇;虫草素

Abstract:

[Objective] To determine the functions of two key enzymes of the mevalonate pathway, phosphomevalonate kinase (CmErg8) and mevalonate diphosphate decarboxylase (CmErg19), in Cordyceps militaris and their effects on the content of ergosterol and cordycepin. [Methods] Bioinformatics analysis was conducted to identify CmErg8 and CmErg19 in C. militaris, and yeast complementation was employed to determine whether their functions were conserved. Furthermore, we employed Agrobacterium tumefaciens-mediated transformation to overexpress CmErg8 and CmErg19 in the auxotrophic mutant CmΔpyrG of C. militaris, so as to observe the effects of CmErg8 and CmErg19 on the content of ergosterol and cordycepin. [Results] CmErg8 and CmErg19 could not complement the temperature sensitivity of the erg8 and erg19 mutants of yeast. The strains overexpressing CmErg8 and CmErg19 showed increased content of ergosterol and cordycepin. Particularly, the cordycepin content increased by about 5 times in the strain overexpressing CmErg19 compared with that in the control. [Conclusion] This study revealed the functions of CmErg8 and CmErg19 in C. militaris and reported that the genes in the ergosterol synthesis pathway of C. militaris affected the content of cordycepin for the first time.

Key words:Cordyceps militaris;phosphomevalonate kinase;mevalonate diphosphate decarboxylase;ergosterol;cordycepin