Nicotine is the primary alkaloid found in tobacco plants. Nearly everyone knows that it causes the addictive nature of cigarettes, cigars and snuff - some still experience this first hand. Less known is that nicotine, under the names Nico-Fume, Black Leaf 40 (a 40% solution of nicotine), Tendust and others, can be used as an insecticide. This practice is rare within the United States yet much is still sold outside the US for this purpose.
In Arthrobacter nicotinovorans (Grether-Beck et al., 1994) and Arthrobacter oxydans (Gherna et al., 1965), nicotine is converted to both (S)-6-Hydroxynicotine and (R)-6-Hydroxynicotine by nicotine dehydrogenase. Stereospecific enzymes (S)-6-hydroxynicotine oxygenase and (R)-6-hydroxynicotine oxygenase catalyze the formation of 6-hydroxypseudooxynicotine which is degraded through 2,6-dihydroxypyridine (Grether-Beck et al., 1994).
Pseudomonas sp. strains P-34 and JTS-006 convert 6-hydroxypseudooxynicotine to 6-hydroxy-3-succinoylpyridine, which forms 2,5- (rather than 2,6-) dihydroxypyridine (Gherna et al., 1965). Pseudomonas putida biotype A strain S16 uses a varient of this pathway. It delays 6-hydroxylation of the aromatic ring until the formation of 3-succinoylpyridine. This is hydroxylated to form 6-hydroxy-3-succinoylpyridine, and the remaining pathway for that is as shown here (Wang et al., 2007).
The three end products of this degradation as shown here are Maleamate, 4-Methylaminobutyrate, and 2,6-Dihydroxy-N-methylmyosmine. The metabolism of Maleamate continues through the regular microbial channels. 4-Methylaminobutyrate does not accumulate in the medium, yet its degradation pathway has not yet been determined. 2,6-Dihydroxy-N-methylmyosmine formed spontaneously from 2,6-Dihydroxypseudooxynicotine is reported as metabolically inactive in this species.
Organisms which can initiate the pathway are given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in a graphic (15k) format.
(RS)-Nicotine
Arthrobacter nicotinovorans
plasmid pAO1
Arthrobacter oxydans
|
|
+-------+-------+
| |
nicotine | | nicotine
dehydrogenase | | dehydrogenase
| |
v v
(S)-6-Hydroxy- (R)-6-Hydroxy-
nicotine nicotine
| |
(S)-6-hydroxynicotine | | (R)-6-hydroxynicotine
oxygenase | | oxygenase
| |
v v
6-Hydroxypseudooxynicotine ------------+
| | Pseudomonas sp. P-34 and JTS-0006
| 6-hydroxypseudo- |
| oxynicotine | 6-hydroxy-
| monooxygenase v pseudooxynicotine
| | dehydrogenase
spontaneous v |
2,6-Dihydroxy- <-------------- 2,6-Dihydroxypseudooxynicotine |
N-methylmyosmine | |
| 2,6-dihydroxy- v
| pseudo- 6-Hydroxy-
| oxynicotine 3-succinoylpyridine
| hydrolase |
| |
+-------------------------------+ | 6-hydroxy-
| | | 3-succinoyl-
| | | pyridine
v v | hydrolase
4-Methylaminobutyrate 2,6-Dihydroxypyridine |
| | |
| 2,6-dihydroxy- | v
A v pyridine oxidase | 2,5-Dihydroxypyridine + Succinic semialdehyde
| | | |
| v | |
v 2,3,6-Trihydroxypyridine | | succinic semialdehyde
Carbon Dioxide | | 2,5-dihydroxy- | dehydrogenase
| | pyridine |
B v | 5,6-dioxygenase v
| | Succinate
| | |
v | |
Maleamate <-------------------+ |
| v
| Intermediary
v Metabolism
Intermediary (KEGG)
Metabolism
(KEGG)
Page Author(s): Ben Vickers, Meaghan Fitzgerald, Sean Anderson and Michael Turnbull
April 25, 2008 Contact Us
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