Isolation and Characterization of Reticuline N-Methyltransferase Involved in Biosynthesis of the Aporphine Alkaloid Magnoflorine in Opium Poppy
Notice bibliographique
Résumé
Benzylisoquinoline alkaloids are a large group of plant-specialized metabolites displaying an array of biological and pharmacological properties associated with numerous structural scaffolds and diverse functional group modification. N-Methylation is one of the most common tailoring reactions, yielding tertiary and quaternary pathway intermediates and products. Two N-methyltransferases accepting (i) early 1-benzylisoquinoline intermediates possessing a secondary amine and leading to the key branch-point intermediate (S)-reticuline and (ii) downstream protoberberines containing a tertiary amine and forming quaternary intermediates destined for phthalideisoquinolines and antimicrobial benzo[c]phenanthridines were previously characterized. We report the isolation and characterization of a phylogenetically related yet functionally distinct N-methyltransferase (NMT) from opium poppy (Papaver somniferum) that primarily accepts 1-benzylisoquinoline and aporphine substrates possessing a tertiary amine. The preferred substrates were the R and S conformers of reticuline and the aporphine (S)-corytuberine, which are proposed intermediates in the biosynthesis of magnoflorine, a quaternary aporphine alkaloid common in plants. Suppression of the gene encoding reticuline N-methyltransferase (RNMT) using virus-induced gene silencing in opium poppy resulted in a significant decrease in magnoflorine accumulation and a concomitant increase in corytuberine levels in roots. RNMT transcript levels were also most abundant in roots, in contrast to the distribution of transcripts encoding other NMTs, which occur predominantly in aerial plant organs. The characterization of a third functionally unique NMT involved in benzylisoquinoline alkaloid metabolism will facilitate the establishment of structure-function relationships among a large group of related enzymes. Benzylisoquinoline alkaloids are a large group of plant-specialized metabolites displaying an array of biological and pharmacological properties associated with numerous structural scaffolds and diverse functional group modification. N-Methylation is one of the most common tailoring reactions, yielding tertiary and quaternary pathway intermediates and products. Two N-methyltransferases accepting (i) early 1-benzylisoquinoline intermediates possessing a secondary amine and leading to the key branch-point intermediate (S)-reticuline and (ii) downstream protoberberines containing a tertiary amine and forming quaternary intermediates destined for phthalideisoquinolines and antimicrobial benzo[c]phenanthridines were previously characterized. We report the isolation and characterization of a phylogenetically related yet functionally distinct N-methyltransferase (NMT) from opium poppy (Papaver somniferum) that primarily accepts 1-benzylisoquinoline and aporphine substrates possessing a tertiary amine. The preferred substrates were the R and S conformers of reticuline and the aporphine (S)-corytuberine, which are proposed intermediates in the biosynthesis of magnoflorine, a quaternary aporphine alkaloid common in plants. Suppression of the gene encoding reticuline N-methyltransferase (RNMT) using virus-induced gene silencing in opium poppy resulted in a significant decrease in magnoflorine accumulation and a concomitant increase in corytuberine levels in roots. RNMT transcript levels were also most abundant in roots, in contrast to the distribution of transcripts encoding other NMTs, which occur predominantly in aerial plant organs. The characterization of a third functionally unique NMT involved in benzylisoquinoline alkaloid metabolism will facilitate the establishment of structure-function relationships among a large group of related enzymes.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».