Characterization of 10-Hydroxygeraniol Dehydrogenase from Catharanthus roseus Reveals Cascaded Enzymatic Activity in Iridoid Biosynthesis
Characterization of 10-Hydroxygeraniol Dehydrogenase from Catharanthus roseus Reveals Cascaded Enzymatic Activity in Iridoid Biosynthesis
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DOI：
10.1038/srep08258
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发表时间：
2015-02-05
影响因子：
4.6
通讯作者：
Thulasiram, Hirekodathakallu V.
中科院分区：
文献类型：
--
作者：
Krithika, Ramakrishnan;Srivastava, Prabhakar Lal;Thulasiram, Hirekodathakallu V.
长春花[L.]是单萜吲哚生物碱（MIA）的主要来源，MIA由于其治疗价值而受到显著关注。这些分子通过中间体顺式-反式-荆芥内酯醇（10-oxogeranial的环化产物）形成。参与MIA生物合成的关键酶之一是NAD（P）（+）依赖性氧化还原酶系统，10-羟基香叶醇脱氢酶（Cr 10 HGO），其催化10-羟基香叶醇经由10-氧代香叶醇或10-羟基香叶醛形成10-氧代香叶醛。本工作描述了从C. roseus及其在环烯醚萜生物合成中的作用。底物特异性研究表明，Cr 10 HGO对底物如10-羟基香叶醇、10-氧代香叶醇或10-羟基香叶醛的活性优于单羟基线性萜烯衍生物。进一步观察到，在NADP（+）存在下，10-羟基香叶醇与Cr 10 HGO和环烯醚萜合酶（CrIDS）孵育产生主要代谢物，通过比较其保留时间、质量裂解模式和与合成化合物的共注射研究，其特征在于（1 R，4aS，7S，7aR）-荆芥内酯醇。这些结果表明，Cr 10 HGO与环烯醚萜合成酶在环烯醚萜生物合成的重要中间体（1 R，4aS，7S，7aR）-荆芥内酯醇的合成中具有协同活性。
Catharanthus roseus [L.] is a major source of the monoterpene indole alkaloids (MIAs), which are of significant interest due to their therapeutic value. These molecules are formed through an intermediate, cis-trans-nepetalactol, a cyclized product of 10-oxogeranial. One of the key enzymes involved in the biosynthesis of MIAs is an NAD(P)(+) dependent oxidoreductase system, 10-hydroxygeraniol dehydrogenase (Cr10HGO), which catalyses the formation of 10-oxogeranial from 10-hydroxygeraniol via 10-oxogeraniol or 10-hydroxygeranial. This work describes the cloning and functional characterization of Cr10HGO from C. roseus and its role in the iridoid biosynthesis. Substrate specificity studies indicated that, Cr10HGO has good activity on substrates such as 10-hydroxygeraniol, 10-oxogeraniol or 10-hydroxygeranial over monohydroxy linear terpene derivatives. Further it was observed that incubation of 10-hydroxygeraniol with Cr10HGO and iridoid synthase (CrIDS) in the presence of NADP(+) yielded a major metabolite, which was characterized as (1R, 4aS, 7S, 7aR)-nepetalactol by comparing its retention time, mass fragmentation pattern, and co-injection studies with that of the synthesized compound. These results indicate that there is concerted activity of Cr10HGO with iridoid synthase in the formation of (1R, 4aS, 7S, 7aR)-nepetalactol, an important intermediate in iridoid biosynthesis.