8a3n
Geissoschizine synthase from Catharanthus roseus - binary complex with NADP+Geissoschizine synthase from Catharanthus roseus - binary complex with NADP+
Structural highlights
FunctionGS_CATRO Component of the seco-iridoid and derivatives monoterpenoid indole alkaloids (MIAs, e.g. catharanthine, tabersonine, vincadifformine, vindoline, vincristine, quinine and strychnine) biosynthesis pathway. Catalyzes iminium reduction on 4,21-dehydrogeissoschizine to produce 19E-geissoschizine, precursor of catharanthine and tabersonine derivatives (PubMed:29147812, PubMed:30256480). May also catalyze the production of reactive intermediate used by the HL1, HL2, HL3 and HL4 to form catharanthine, vincadifformine and tabersonine (PubMed:30256480).[1] [2] Publication Abstract from PubMedMedium-chain alcohol dehydrogenases (ADHs) comprise a highly conserved enzyme family that catalyse the reversible reduction of aldehydes. However, recent discoveries in plant natural product biosynthesis suggest that the catalytic repertoire of ADHs has been expanded. Here we report the crystal structure of dihydroprecondylocarpine acetate synthase (DPAS), an ADH that catalyses the non-canonical 1,4-reduction of an alpha,beta -unsaturated iminium moiety. Comparison with structures of plant-derived ADHs suggest the 1,4-iminium reduction does not require a proton relay or the presence of a catalytic zinc ion in contrast to canonical 1,2-aldehyde reducing ADHs that require the catalytic zinc and a proton relay. Furthermore, ADHs that catalysed 1,2-iminium reduction required the presence of the catalytic zinc and the loss of the proton relay. This suggests how the ADH active site can be modified to perform atypical carbonyl reductions, providing insight into how chemical reactions are diversified in plant metabolism. Expansion of the Catalytic Repertoire of Alcohol Dehydrogenases in Plant Metabolism.,Langley C, Tatsis E, Hong B, Nakamura Y, Paetz C, Stevenson CE, Basquin J, Lawson DM, Caputi L, O'Connor SE Angew Chem Int Ed Engl. 2022 Oct 5. doi: 10.1002/anie.202210934. PMID:36198083[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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