The Biosynthesis of Nicotine from Isotopically Labeled Nicotinic Acids<sup>1</sup>

Dawson, Ray F.; Christman, David R.; D’Adamo, Amedeo F.; Solt, Marie L.; Wolf, Alfred P.

doi:10.1021/ja01495a059

Cited by 76 publications

(34 citation statements)

References 4 publications

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“…6-Hydroxynicotinic acid and its C-3 derivatives have a hydroxyl group at analogous positions. Although 6-hydroxynicotinic acid was identified as a metabolite of nicotinic acid in tobacco roots, it was not incorporated into nicotine when administered to the tobacco roots (Dawson et al 1960;Mizusaki et al 1970). The identity of the true A622 substrate is a matter of speculation but its structure may be suited to the formation of a presumed quinonemethide intermediate.…”

Section: A622 As a Pip-family Reductasementioning

confidence: 99%

A PIP-family protein is required for biosynthesis of tobacco alkaloids

2008

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Plants in the Nicotiana genus produce nicotine and related pyridine alkaloids as a part of their chemical defense against insect herbivores. These alkaloids are formed by condensation of a derivative of nicotinic acid, but the enzyme(s) involved in the final condensation step remains elusive. In Nicotiana tabacum, an orphan reductase A622 and its close homolog A622L are coordinately expressed in the root, upregulated by methyl jasmonate treatment, and controlled by the NIC regulatory loci specific to the biosynthesis of tobacco alkaloids. Conditional suppression of A622 and A622L by RNA interference inhibited cell growth, severely decreased the formation of all tobacco alkaloids, and concomitantly induced an accumulation of nicotinic acid beta-N-glucoside, a probable detoxification metabolite of nicotinic acid, in both hairy roots and methyl jasmonate-elicited cultured cells of tobacco. N-methylpyrrolinium cation, a precursor of the pyrrolidine moiety of nicotine, also accumulated in the A622(L)-knockdown hairy roots. We propose that the tobacco A622-like reductases of the PIP family are involved in either the formation of a nicotinic acid-derived precursor or the final condensation reaction of tobacco alkaloids.

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Section: A622 As a Pip-family Reductasementioning

confidence: 99%

A PIP-family protein is required for biosynthesis of tobacco alkaloids

2008

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“…When isotopically labeled nicotinic acids were fed to tobacco plants, the isotope labels were incorporated into the pyridine ring of nicotine (Dawson et al, 1956). Interestingly, the tritium label at C-6 of nicotinic acid was specifically lost in isolated nicotine (Dawson et al, 1960; Leete and Liu, 1973), suggesting that the C-6 position is first oxidized and subsequently reduced during the incorporation of nicotinic acid into nicotine. The putative oxidoreductases involved in the activation of nicotinic acid and the mechanisms behind the nicotine-forming condensation reactions between a nicotinic acidderived intermediate and the N-methylpyrrolinium cation are yet to be clarified.…”

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confidence: 99%

Vacuole-Localized Berberine Bridge Enzyme-Like Proteins Are Required for a Late Step of Nicotine Biosynthesis in Tobacco1

et al. 2011

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Tobacco (Nicotiana tabacum) plants synthesize nicotine and related pyridine-type alkaloids, such as anatabine, in their roots and accumulate them in their aerial parts as chemical defenses against herbivores. Herbivory-induced jasmonate signaling activates structural genes for nicotine biosynthesis and transport by way of the NICOTINE (NIC) regulatory loci. The biosynthesis of tobacco alkaloids involves the condensation of an unidentified nicotinic acid-derived metabolite with the N-methylpyrrolinium cation or with itself, but the exact enzymatic reactions and enzymes involved remain unclear. Here, we report that jasmonate-inducible tobacco genes encoding flavin-containing oxidases of the berberine bridge enzyme family (BBLs) are expressed in the roots and regulated by the NIC loci. When expression of the BBL genes was suppressed in tobacco hairy roots or in tobacco plants, nicotine production was highly reduced, with a gradual accumulation of a novel nicotine metabolite, dihydromethanicotine. In the jasmonate-elicited cultured tobacco cells, suppression of BBL expression efficiently inhibited the formation of anatabine and other pyridine alkaloids. Subcellular fractionation and localization of green fluorescent protein-tagged BBLs showed that BBLs are localized in the vacuoles. These results indicate that BBLs are involved in a late oxidation step subsequent to the pyridine ring condensation reaction in the biosynthesis of tobacco alkaloids.

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“…Elsewhere, we report the fact (9) that supplying precursors of nicotine to excised root cultures of N. tabacum does not increase nicotine yields. The present svstem might be used to learn whether nicotine production could be diverted to anabasine production, or vice versa, by supplying the corresponding precursor in excess.…”

Section: Investigations Of Nicotiana Alkaloid Biogenesismentioning

confidence: 78%

“…Nicotinic acid labeled with tritium in position 2 was prepared from 2-bromo-3-picoline by methods described elsewhere (9). Two preparations were employed with specific activities 2.25 X 105 and 2.57 X 105 dpm/mg, respectively.…”

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confidence: 99%