Inverted stereocontrol of iridoid synthase in snapdragon

© 2017 by The American Society for Biochemistry and Molecular Biology, Inc..

The natural product class of iridoids, found in various species of flowering plants, harbors astonishing chemical complexity. The discovery of iridoid biosynthetic genes in the medicinal plant Catharanthus roseus has provided insight into the biosynthetic origins of this class of natural product. However, not all iridoids share the exact five- to six-bicyclic ring scaffold of the Catharanthus iridoids. For instance, iridoids in the ornamental flower snapdragon (Antirrhinum majus, Plantaginaceae family) are derived from the C7 epimer of this scaffold. Here we have cloned and characterized the iridoid synthase enzyme from A. majus (AmISY), the enzyme that is responsible for converting 8-oxogeranial into the bicyclic iridoid scaffold in a two-step reduction-cyclization sequence. Chiral analysis of the reaction products reveals that AmISY reduces C7 to generate the opposite stereoconfiguration in comparison with the Catharanthus homologue CrISY. The catalytic activity of AmISY thus explains the biosynthesis of 7-epi-iridoids in Antirrhinum and related genera. However, although the stereoselectivity of the reduction step catalyzed by AmISY is clear, in both AmISY and CrISY, the cyclization step produces a diastereomeric mixture. Although the reduction of 8-oxogeranial is clearly enzymatically catalyzed, the cyclization step appears to be subject to less stringent enzyme control.

Medienart:

E-Artikel

Erscheinungsjahr:

2017

Erschienen:

2017

Enthalten in:

Zur Gesamtaufnahme - volume:292

Enthalten in:

The Journal of biological chemistry - 292(2017), 35 vom: 01. Sept., Seite 14659-14667

Sprache:

Englisch

Beteiligte Personen:

Kries, Hajo [VerfasserIn]
Kellner, Franziska [VerfasserIn]
Kamileen, Mohamed Omar [VerfasserIn]
O'Connor, Sarah E [VerfasserIn]

Links:

Volltext

Themen:

53-59-8
Acyclic Monoterpenes
Alcohol dehydrogenase (ADH)
Alkyl and Aryl Transferases
Citral
Comparative Study
Decaprenoic acid
EC 2.5.-
EC 2.5.1.-
Iridoids
Journal Article
Monoterpenes
NADP
Natural product
Natural product biosynthesis
PL902IKN0A
Plant Proteins
Plant biochemistry
Recombinant Fusion Proteins
Recombinant Proteins
T7EU0O9VPP
Terpene synthase
Terpenes
Terpenoid

Anmerkungen:

Date Completed 26.09.2017

Date Revised 16.07.2022

published: Print-Electronic

PDB: 5DF1

Citation Status MEDLINE

doi:

10.1074/jbc.M117.800979

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM273774468