NaPMT1.2 Notes

• UniProt curates Q93XQ4 as Putrescine N-methyltransferase 2 and places it in nicotine biosynthesis with predominant root expression. [file:NICAT/NaPMT1.2/NaPMT1.2-uniprot.txt "DE RecName: Full=Putrescine N-methyltransferase 2"; "CC -!- PATHWAY: Alkaloid biosynthesis; nicotine biosynthesis."; "CC -!- TISSUE SPECIFICITY: Mainly expressed in roots."]
• PMT catalyzes S-adenosylmethionine-dependent methylation of putrescine to N-methylputrescine, the first specific metabolite on the route to nicotine. PMID:19651420
• TreeGrafter assignment to spermidine synthase reflects PMT's evolutionary origin from spermidine synthase rather than its present catalytic activity. PMID:19651420
• In N. attenuata, Winz and Baldwin cloned PMT1 and PMT2 and found that both root PMT transcripts rose after MeJA, wounding, and Manduca sexta herbivory, while ethylene suppressed this induction. PMID:11299398
• The 2017 Nicotiana genome paper places root nicotine biosynthesis in N. attenuata as a duplicated specialization of polyamine and NAD metabolism, consistent with PMT as a root defense-pathway enzyme. PMID:28536194
• The full glucosylation preprint keeps PMT in the completed pathway logic by relying on an ODC-PMT-MPO module to make N-methylpyrrolinium during in planta nicotine reconstruction. [file:projects/NICOTINE_BIOSYNTHESIS/biorxiv-nicotine-glucosylation-notes.md "In N. benthamiana leaves, the in planta reconstruction uses ODC, PMT, and MPO to generate N-methylpyrrolinium, then depends on the glucosylation-late-pathway module to make labelled nicotine"; "ODC, PMT, and MPO remain part of the minimal upstream module needed to feed the completed pathway."]