NaQPT2_candidate_QPT_1 Notes

• UniProt curates A0A1J6IKI8 as nicotinate-nucleotide diphosphorylase (carboxylating), the quinolinate phosphoribosyltransferase/NadC chemistry that links quinolinate to NAD and nicotine pathway annotations. [file:NICAT/NaQPT2_candidate_QPT_1/NaQPT2_candidate_QPT_1-uniprot.txt "DE RecName: Full=nicotinate-nucleotide diphosphorylase (carboxylating)"; "CC -!- CATALYTIC ACTIVITY: Reaction=nicotinate beta-D-ribonucleotide + CO2 + diphosphate = quinolinate + 5-phospho-alpha-D-ribose 1-diphosphate + 2 H(+)"; "CC -!- PATHWAY: Alkaloid biosynthesis; nicotine biosynthesis."; "CC -!- PATHWAY: Cofactor biosynthesis; NAD(+) biosynthesis; nicotinate D-ribonucleotide from quinolinate: step 1/1."]
• UniProt assigns QPT_1 to the NadC/ModD family and to both NAD+ biosynthetic process and nicotine biosynthetic process, so it is also a credible pathway candidate rather than a generic unrelated transferase. [file:NICAT/NaQPT2_candidate_QPT_1/NaQPT2_candidate_QPT_1-uniprot.txt "CC -!- SIMILARITY: Belongs to the NadC/ModD family."; "DR GO; GO:0009435; P:NAD+ biosynthetic process; IEA:UniProtKB-UniPathway."; "DR GO; GO:0042179; P:nicotine biosynthetic process; IEA:UniProtKB-UniPathway."]
• The N. attenuata genome paper attributes nicotine-pathway evolution in part to duplications within the NAD pathway, which is why both QPT_0 and QPT_1 deserve explicit paralog resolution. PMID:28536194
• The full glucosylation preprint keeps QPT2 inside the coordinated nicotine gene set by placing it among the stronger tobacco genes correlated with UGT1, which supports continued QPT paralog review without resolving the NICAT split. [file:projects/NICOTINE_BIOSYNTHESIS/biorxiv-nicotine-glucosylation-notes.md "genes most correlated with UGT1 include BBLa, QPT2, beta-GD1, A622, PMT1, PMT2, PMT3, and MATE1"; "QPT2 and AO2 are supported at the level of coordinated pathway expression and pathway framing, but this paper does not directly assay their enzymatic roles."]
• QPT_1 remains a plausible NaQPT2 candidate, but the public annotations alone do not resolve whether it is the pathway-specialized copy versus QPT_0. [file:NICAT/NaQPT2_candidate_QPT_1/NaQPT2_candidate_QPT_1-uniprot.txt "GN Name=QPT_1"; "CC -!- PATHWAY: Alkaloid biosynthesis; nicotine biosynthesis."]