Heteromeric and Homomeric Geranyl Diphosphate Synthases from Catharanthus roseus and Their Role in Monoterpene Indole Alkaloid Biosynthesis

作     者：Avanish Rai Shachi S. Smita Anup Kumar Singh Karuna Shanker Dinesh A. Nagegowda 

作者机构：CSIR-Central Institute of Medicinal and Aromatic Plants Research Centre Bangalore 560065 India CSIR-Central Institute of Medicinal and Aromatic Plants Lucknow 226015 India 

出 版 物：《Molecular Plant》 (分子植物（英文版）)

年 卷 期：2013年第6卷第5期

页      面：1531-1549页

核心收录：

学科分类：0710[理学-生物学] 071001[理学-植物学] 1007[医学-药学(可授医学、理学学位)] 100705[医学-微生物与生化药学] 07[理学] 10[医学] 

基　　金：TheDepartmentofBiotechnology GovernmentofIndia fortheRamalingaswamiFellowship(BTIHRDI3512412006) 

主　　题：C. roseus monoterpene indole alkaloids geranyl diphosphate synthase heteromer homomer large subunit small subunit vindoline. 

摘      要：Catharanthus roseus is the sole source of two most important monoterpene indole alkaloid （MIA） anti- cancer agents： vinblastine and vincristine. MIAs possess a terpene and an indole moiety derived from terpenoid and shikimate pathways, respectively. Geranyl diphosphate （GPP）, the entry point to the formation of terpene moiety, is a product of the condensation of isopentenyl diphosphate （IPP） and dimethylallyl diphosphate （DMAPP） by GPP synthase （GPPS）. Here, we report three genes encoding proteins with sequence similarity to large subunit （***） and small subunit （***） of heteromeric GPPSs, and a homomeric GPPSs. *** is a bifunctional enzyme producing both GPP and geranyl geranyl diphosphate （GGPP）, *** is inactive, whereas CrGPPS is a homomeric enzyme forming GPP. Co-expression of both subunits in Escherichia coil resulted in heteromeric enzyme with enhanced activity producing only GPR While *** and CrGPPS showed higher expression in older and younger leaves, respectively, *** showed an increasing trend and decreased gradually. Methyl jasmonate （MelA） treatment of leaves sig- nificantly induced the expression of only ***. GFP localization indicated that *** is plastidial whereas CrGPPS is mitochondrial. Transient overexpression of *** in C. roseus leaves resulted in increased vindoline, immediate monomeric precursor of vinblastine and vincristine. Although C. roseus has both heteromeric and homomeric GPPS enzymes, our results implicate the involvement of only heteromeric GPPS with *** regulating the GPP flux for MIA biosynthesis.