Zea mays(maize)is an important agricultural crop that produces a variety of valuable terpenoids,including several triterpenoids.However,no oxidosqualene cyclase(OSC)enzymes,which catalyze the first step in triterpenoi...Zea mays(maize)is an important agricultural crop that produces a variety of valuable terpenoids,including several triterpenoids.However,no oxidosqualene cyclase(OSC)enzymes,which catalyze the first step in triterpenoid biosynthesis,have been identified in maize.Here,we identified a novel OSC(ZmOSC1)in maize using a combination of genomic mining and phylogenetic analyses.To functionally characterize the candidate OSC,we constructed a yeast strain that produced high levels of 2,3-oxidosqualene.When ZmOSC1 was expressed in this strain,three compounds were detected and identified as hop-17(21)-en-3-ol,hopenol B and simiarenol,respectively.For their biosynthesis,we proposed a potential cyclization mechanism catalyzed by ZmOSC1 via the generation of a dammarenyl cation,followed by sequential cationic ring expansion,cyclization,cationic migration and further proton elimination.This study discovered and characterized an OSC from maize for the first time,and laid a foundation to produce three bioactive pentacyclic triterpenes,hop-17(21)-en-3-ol,hopenol B and simiarenol,using synthetic biology approaches.展开更多
基金This work was financially supported by the National Key Research and Development Program of China(Grant Nos.2020YFA0907900&2019YFA0905700)the National Science Resource Investigation Program of China(2019FY100100)+2 种基金the international Partnership Program of Chinese Academy of Sciences(153D31KYSB20170121)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB27020206)the Strategic Biological Resources Service Network Plan of the Chinese Academy of Sciences(Grant No.KFJ-BRP-009&KFJ-BRP-017-60).
文摘Zea mays(maize)is an important agricultural crop that produces a variety of valuable terpenoids,including several triterpenoids.However,no oxidosqualene cyclase(OSC)enzymes,which catalyze the first step in triterpenoid biosynthesis,have been identified in maize.Here,we identified a novel OSC(ZmOSC1)in maize using a combination of genomic mining and phylogenetic analyses.To functionally characterize the candidate OSC,we constructed a yeast strain that produced high levels of 2,3-oxidosqualene.When ZmOSC1 was expressed in this strain,three compounds were detected and identified as hop-17(21)-en-3-ol,hopenol B and simiarenol,respectively.For their biosynthesis,we proposed a potential cyclization mechanism catalyzed by ZmOSC1 via the generation of a dammarenyl cation,followed by sequential cationic ring expansion,cyclization,cationic migration and further proton elimination.This study discovered and characterized an OSC from maize for the first time,and laid a foundation to produce three bioactive pentacyclic triterpenes,hop-17(21)-en-3-ol,hopenol B and simiarenol,using synthetic biology approaches.
