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Characterization of 10-hydroxygeraniol dehydrogenase from Catharanthus roseus reveals cascaded enzymatic activity in iridoid biosynthesis.

Krithika R, Srivastava PL, Rani B, Kolet SP, Chopade M, Soniya M, Thulasiram HV - Sci Rep (2015)

Bottom Line: Catharanthus roseus [L.] is a major source of the monoterpene indole alkaloids (MIAs), which are of significant interest due to their therapeutic value.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.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.

View Article: PubMed Central - PubMed

Affiliation: Chemical Biology Unit, Division of Organic Chemistry, CSIR- National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008.

ABSTRACT
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.

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Iridoid Biosynthetic Pathway cyclizes 10-oxogeranial into equilibrium mixture of cis-trans-nepetalactol and iridodials.The bicyclic compound, cis-trans-nepetalactol is the key intermediate.
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f1: Iridoid Biosynthetic Pathway cyclizes 10-oxogeranial into equilibrium mixture of cis-trans-nepetalactol and iridodials.The bicyclic compound, cis-trans-nepetalactol is the key intermediate.

Mentions: Monoterpene indole alkaloids (MIAs) are a multifarious class of natural products with distinct chemical and biological properties123. To date, over 3000 MIAs are known with diverse structures and biological activities. The Apocynaceae family plant, C. roseus is a rich source of the iridoid-derived MIAs and is known to contain over 200 alkaloids in various tissues. Two MIAs from this plant, vincristine and vinblastine, are widely prescribed as potent anti-cancer agents45. These MIAs were synthesized from the condensation of tryptamine and the iridoid monoterpene, secologanin. The MIAs' biosynthesis diverges from the isoprenoid biosynthetic pathway at the 1′-4 chain elongation intermediate geranyl diphosphate (GPP) formed through head-to-tail condensation of isopentenyl diphosphate (IPP) with dimethylallyl diphsophate (DMAPP) catalyzed by Geranyl diphosphate synthase (CrGDS)6. Geraniol synthase (CrGS)7 hydrolyses GPP into geraniol, which undergoes hydroxylation at C10 to form 10-hydroxygeraniol by the cytochrome P450 system, Geraniol 10-hydroxylase (CrG10H)8 (Fig. 1). Feeding experiments with labelled 10-hydroxygeraniol, 10-hydroxynerol and iridodiol in C. roseus and Lonicera morrowii suspension cultures clearly indicated that 10-hydroxygeraniol is oxidized to 10-oxogeranial by the oxidoreductase system, 10-hydroxygeraniol dehydrogenase (10HGO)9101112 (Fig. 1). Recently, a short chain reductive cyclase, iridoid synthase (CrIDS)13, which cyclises 10-oxogeranial into an equilibrium mixture of cis-trans-nepetalactol and iridodials, has been characterized. The bicyclic compound, cis-trans-nepetalactol, is the key intermediate involved in the biosynthesis of a structurally diverse array of MIAs. Experiments using labelled intermediates indicated that one of the committed steps during the biosynthesis of iridoids is the oxidation of 10-hydroxygeraniol to its dialdehyde cognate, 10-oxogeranial11. Ikeda et al.14 had purified the NADP+ dependent oxidoreductase protein from Rauwolfia serpentina cells which could convert 10-hydroxygeraniol into 10-oxogeraniol, 10-hydroxygeranial and 10-oxogeranial. However, it was found to have better activity on nerol and geraniol. The present work describes the cloning and functional characterization of Cr10HGO and the study on the orchestration of enzyme activity of Cr10HGO with CrIDS in the biosynthesis of desired (1R, 4aS, 7S, 7aR)-nepetalactol (Fig. 1). Also, substrate specificity studies of Cr10HGO indicated that, it has broad substrate specificity with 10-hydroxygeraniol, 10-oxogeraniol or 10-hydroxygeranial over monohydroxy linear terpene derivatives.


Characterization of 10-hydroxygeraniol dehydrogenase from Catharanthus roseus reveals cascaded enzymatic activity in iridoid biosynthesis.

Krithika R, Srivastava PL, Rani B, Kolet SP, Chopade M, Soniya M, Thulasiram HV - Sci Rep (2015)

Iridoid Biosynthetic Pathway cyclizes 10-oxogeranial into equilibrium mixture of cis-trans-nepetalactol and iridodials.The bicyclic compound, cis-trans-nepetalactol is the key intermediate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4317706&req=5

f1: Iridoid Biosynthetic Pathway cyclizes 10-oxogeranial into equilibrium mixture of cis-trans-nepetalactol and iridodials.The bicyclic compound, cis-trans-nepetalactol is the key intermediate.
Mentions: Monoterpene indole alkaloids (MIAs) are a multifarious class of natural products with distinct chemical and biological properties123. To date, over 3000 MIAs are known with diverse structures and biological activities. The Apocynaceae family plant, C. roseus is a rich source of the iridoid-derived MIAs and is known to contain over 200 alkaloids in various tissues. Two MIAs from this plant, vincristine and vinblastine, are widely prescribed as potent anti-cancer agents45. These MIAs were synthesized from the condensation of tryptamine and the iridoid monoterpene, secologanin. The MIAs' biosynthesis diverges from the isoprenoid biosynthetic pathway at the 1′-4 chain elongation intermediate geranyl diphosphate (GPP) formed through head-to-tail condensation of isopentenyl diphosphate (IPP) with dimethylallyl diphsophate (DMAPP) catalyzed by Geranyl diphosphate synthase (CrGDS)6. Geraniol synthase (CrGS)7 hydrolyses GPP into geraniol, which undergoes hydroxylation at C10 to form 10-hydroxygeraniol by the cytochrome P450 system, Geraniol 10-hydroxylase (CrG10H)8 (Fig. 1). Feeding experiments with labelled 10-hydroxygeraniol, 10-hydroxynerol and iridodiol in C. roseus and Lonicera morrowii suspension cultures clearly indicated that 10-hydroxygeraniol is oxidized to 10-oxogeranial by the oxidoreductase system, 10-hydroxygeraniol dehydrogenase (10HGO)9101112 (Fig. 1). Recently, a short chain reductive cyclase, iridoid synthase (CrIDS)13, which cyclises 10-oxogeranial into an equilibrium mixture of cis-trans-nepetalactol and iridodials, has been characterized. The bicyclic compound, cis-trans-nepetalactol, is the key intermediate involved in the biosynthesis of a structurally diverse array of MIAs. Experiments using labelled intermediates indicated that one of the committed steps during the biosynthesis of iridoids is the oxidation of 10-hydroxygeraniol to its dialdehyde cognate, 10-oxogeranial11. Ikeda et al.14 had purified the NADP+ dependent oxidoreductase protein from Rauwolfia serpentina cells which could convert 10-hydroxygeraniol into 10-oxogeraniol, 10-hydroxygeranial and 10-oxogeranial. However, it was found to have better activity on nerol and geraniol. The present work describes the cloning and functional characterization of Cr10HGO and the study on the orchestration of enzyme activity of Cr10HGO with CrIDS in the biosynthesis of desired (1R, 4aS, 7S, 7aR)-nepetalactol (Fig. 1). Also, substrate specificity studies of Cr10HGO indicated that, it has broad substrate specificity with 10-hydroxygeraniol, 10-oxogeraniol or 10-hydroxygeranial over monohydroxy linear terpene derivatives.

Bottom Line: Catharanthus roseus [L.] is a major source of the monoterpene indole alkaloids (MIAs), which are of significant interest due to their therapeutic value.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.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.

View Article: PubMed Central - PubMed

Affiliation: Chemical Biology Unit, Division of Organic Chemistry, CSIR- National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus