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Cloning and characterization of norbelladine synthase catalyzing the first committed reaction in Amaryllidaceae alkaloid biosynthesis

Singh, Aparna, Massicotte, Marie-Ange, Garand, Ariane, Tousignant, Laurence, Ouellette, Vincent, Bérubé, Gervais, Desgagné-Penix, Isabel
BMC plant biology 2018 v.18 no.1 pp. 338
(S)-norcoclaurine synthase, Escherichia coli, Narcissus pseudonarcissus, Papaver somniferum, alkaloids, amino acids, biosynthesis, catalytic activity, complementary DNA, databases, dopamine, medicinal properties, metabolic engineering, metabolites, nucleotide sequences, phylogeny, proteins, synthetic biology, tandem mass spectrometry, transcriptomics, tyramine
BACKGROUND: Amaryllidaceae alkaloids (AAs) are a large group of plant-specialized metabolites displaying an array of biological and pharmacological properties. Previous investigations on AA biosynthesis have revealed that all AAs share a common precursor, norbelladine, presumably synthesized by an enzyme catalyzing a Mannich reaction involving the condensation of tyramine and 3,4-dihydroxybenzaldehyde. Similar reactions have been reported. Specifically, norcoclaurine synthase (NCS) which catalyzes the condensation of dopamine and 4-hydroxyphenylacetaldehyde as the first step in benzylisoquinoline alkaloid biosynthesis. RESULTS: With the availability of wild daffodil (Narcissus pseudonarcissus) database, a transcriptome-mining search was performed for NCS orthologs. A candidate gene sequence was identified and named norbelladine synthase (NBS). NpNBS encodes for a small protein of 19 kDa with an anticipated pI of 5.5. Phylogenetic analysis showed that NpNBS belongs to a unique clade of PR10/Bet v1 proteins and shared 41% amino acid identity to opium poppy NCS1. Expression of NpNBS cDNA in Escherichia coli produced a recombinant enzyme able to condense tyramine and 3,4-DHBA into norbelladine as determined by high-resolution tandem mass spectrometry. CONCLUSIONS: Here, we describe a novel enzyme catalyzing the first committed step of AA biosynthesis, which will facilitate the establishment of metabolic engineering and synthetic biology platforms for the production of AAs.