The enzyme, found mostly in bacteria (mostly, but not exclusively in Gram-positive bacteria), fungi, and plants, participates in the degradation of quinate and shikimate with a strong preference for NAD+ as a cofactor. While the enzyme can act on both quinate and shikimate, activity is higher with the former. cf. EC 1.1.5.8, quinate/shikimate dehydrogenase (quinone), EC 1.1.1.282, quinate/shikimate dehydrogenase [NAD(P)+], and EC 1.1.1.25, shikimate dehydrogenase (NADP+).
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SYSTEMATIC NAME
IUBMB Comments
L-quinate:NAD+ 3-oxidoreductase
The enzyme, found mostly in bacteria (mostly, but not exclusively in Gram-positive bacteria), fungi, and plants, participates in the degradation of quinate and shikimate with a strong preference for NAD+ as a cofactor. While the enzyme can act on both quinate and shikimate, activity is higher with the former. cf. EC 1.1.5.8, quinate/shikimate dehydrogenase (quinone), EC 1.1.1.282, quinate/shikimate dehydrogenase [NAD(P)+], and EC 1.1.1.25, shikimate dehydrogenase (NADP+).
the enzyme also shows activity with shikimate. Clear substrate preference of the enzyme for quinate compared with shikimate both at the pH optimum and in a physiological pH range. The enzyme is strictly NAD(H) dependent
the enzyme also shows activity with shikimate. Clear substrate preference of the enzyme for quinate compared with shikimate both at the pH optimum and in a physiological pH range. The enzyme is strictly NAD(H) dependent
the enzyme also shows high activity with quinate. Clear substrate preference of the enzyme for quinate compared with shikimate both at the pH optimum and in a physiological pH range. The enzyme is strictly NAD(H) dependent
the enzyme also shows high activity with quinate. Clear substrate preference of the enzyme for quinate compared with shikimate both at the pH optimum and in a physiological pH range. The enzyme is strictly NAD(H) dependent
the bifunctional enzyme shows quinate and shikimate dehydrogenase activities, interconversion of 5-dehydroquinate and 5-dehydroshikimate by dehydroquinase, EC 4.2.1.10, favouring 5-dehydroshikimate formation
structure of the potential binding site of quinate and shikimate includign the the completely conserved residues Lys92 and Asp102, overview. The crystal structure reveals that in contrast to shikimate, quinate forms a hydrogen bond to the NAD+. In addition, the hydroxyl group of a conserved active-site threonine hydrogen binds to quinate more effectively than to shikimate. Also, the hydroxyl group of a conserved tyrosine approaches the carboxylate group of quinate more closely than it does the carboxylate group of shikimate, active site structure, overview
quinate dehydrogenase activity is at a maximum around the time of greatest quinic acid accumulation in the early stages (less than 60 days after anthesis) of fruit development. It declines markedly in late fruit development
quinate dehydrogenase activity is at a maximum around the time of greatest quinic acid accumulation in the early stages (less than 60 days after anthesis) of fruit development. It declines markedly in late fruit development, and is higher in species that accumulate the largest amounts of quinic acid (Actinidia chinensis and Actinidia deliciosa)
quinate dehydrogenase activity is at a maximum around the time of greatest quinic acid accumulation in the early stages (less than 60 days after anthesis) of fruit development. It declines markedly in late fruit development, and is higher in species that accumulate the largest amounts of quinic acid (Actinidia chinensis and Actinidia deliciosa)
comparison of EcDQD/SDH, UGT84A25a/b, and UGT84A26a/b expression patterns in Eucalyptus camaldulensis, relative EcDQD/SDH mRNA levels in the leaves, stems, and roots are plotted against the relative UGT84A25a/b and UGT84A26a/b mRNA levels in the same samples, and determination of concentrations of the metabolites in the different tissues, overview
comparison of EcDQD/SDH, UGT84A25a/b, and UGT84A26a/b expression patterns in Eucalyptus camaldulensis, relative EcDQD/SDH mRNA levels in the leaves, stems, and roots are plotted against the relative UGT84A25a/b and UGT84A26a/b mRNA levels in the same samples, and determination of concentrations of the metabolites in the different tissues, overview
link between reactions catalysed by the shikimate pathway enzyme dehydroquinate dehydratase (DQD)/shikimate dehydrogenase (SDH) and quinate dehydrogenase (QDH) involved in quinate metabolism. Shikimate is produced from dehydroquinate via a two-step reaction and subsequently channelled to downstream reactions in the pathway. Quinate is reversibly formed from a side branch of the shikimate pathway from dehydroquinate and may be converted to more structurally complex secondary metabolites or to dehydroquinate to fuel the shikimate pathway
plant SDH enzymes are fused to dehydroquinate dehydratases (DQDs, EC 4.2.1.10) to form bifunctional DQD/SDH enzymes. The DQD activity is observed for EcDQD/SDH1, 2, and 3, but not for EcDQD/SDH4a. Among the active enzymes, EcDQD/SDH1 exhibits the highest DQD activity, followed by EcDQD/SDH2 (about 50% of the EcDQD/SDH1 activity) and EcDQD/SDH3 (about 5% of the EcDQD/SDH1 activity). For shikimate formation from 3-DHS as well as shikimate oxidation to 3-DHS, measurable catalytic activities are detected for EcDQD/SDH1-3, but the activities of EcDQD/SDH2 and 3 are less than 20% of those of EcDQD/SDH1. Regarding the cofactor, EcDQD/SDH1-3 have a clear preference for NADPH/NADP+ over NADH/ NAD+. In contrast, EcDQD/SDH4a and b lack shikimate formation activity. For the reverse reaction, the conversion of shikimate to 3-DHS, EcDQD/SDH4a and b display low enzymatic activity with a preference for NAD+ as the cofactor. Both EcDQD/SDH2 and 3 exhibit relatively high gallate formation activity, in contrast to the low activity of EcDQD/SDH1. The preferred cofactor in this reaction is NADP+. The reversible quinate formation from 3-DHQ is catalyzed only by EcDQD/SDH4a/b, with NADH/NAD+ as the preferred cofactor. The reaction specificity of EcDQD/SDH4a confirms the sequence-based prediction that EcDQD/SDH4a is a functional QDH enzyme. This enzyme should be renamed EcQDHa and its closest relative, EcDQD/SDH4b, should be renamed EcQDHb. The EcDQD/SDH4a and EcDQD/SDH4b genes may represent allelic variants encoding enzymes with 99.2% amino acid identity
the enzyme belongs to the QDH family, phylogenetic reconstruction of the SDH/QDH gene family across land plants, overview. SDH and QDH belong to the same gene family, which diverged into two phylogenetic clades after a defining gene duplication just prior to the angiosperm/gymnosperm split. Non-seed plants that diverged before this duplication harbour only a single gene of this family. Extant representatives from the chlorophytes (Chlamydomonas reinhardtii), bryophytes (Physcomitrella patens) and lycophytes (Selaginella moellendorfii) encoded almost exclusively SDH activity in vitro. A reconstructed ancestral sequence representing the node just prior to the gene duplication also encoded SDH activity. Quinate dehydrogenase activity was gained only in seed plants following gene duplication. Quinate dehydrogenases of gymnosperms, e.g. Pinus taeda, may be reminiscent of an evolutionary intermediate since they encode equal SDH and QDH activities. The second copy in Pinus taeda maintains specificity for shikimate similar to the activity found in the angiosperm SDH sister clade. The codon for a tyrosine residue within the active site displays a signature of positive selection at the node defining the QDH clade, where it changed to a glycine. Replacing the tyrosine with a glycine in a highly shikimate-specific angiosperm SDH is sufficient to gain some QDH function. Thus, very few mutations are necessary to facilitate the evolution of QDH genes. The two proteins from Pinus taeda are chosen to represent the post-duplication SDH and QDH clades from gymnosperms. The single-copy genes from Selaginella moellendorffii, Physcomitrella patens and Chlamydomonas reinhardtii are selected to represent the pre-duplication lycopod, bryophyte and green algal clades, respectively. Thr381 is conserved in most members across all SDH clades but was replaced under positive selection by Gly in the branch leading into the seed plant QDH clade
transfer of carrot enzyme from dark to light conditions shifts MW from 42000 Da to 110000 Da, probably due to association of a regulatory subunit which may be a calciprotein
seconfdary and tertiary enzyme structures, the enzyme is composed of two alphabetaalpha domains containing two discontinuous segments, Asp22-Asn127 and Gly287-Leu302, overview
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
NAD+-dependent enzyme, X-ray diffraction structure determination and anaylsis at 1.64-8.0 A resolution, molecular replacement method, modelling of the ternary complexes, overview
vapor diffusion sitting-drop method at 20°C. Atomic resolution crystal structures of the enzyme in different functional states: with bound NAD+ (binary complex) and as ternary complexes with NADH plus either shikimate or quinate
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GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
high ionic strength, such as 0.1 M (NH4)2SO4, NaCl or phosphate buffer or the presence of 0.1 M quinate or shikimate protects against thermal inactivation
recombinant GST-tagged enzyme from Escherichia coli strain BL21-CodonPlus(DE3)-RIL by glutathione affinity chromatography and tag cleavage through thrombin
Characterization of the 3-dehydroquinase domain of the pentafunctional AROM protein, and the quinate dehydrogenase from Aspergillus nidulans, and the overproduction of the type II 3-dehydroquinase from Neurospora crassa
Enzyme-substrate complexes of the quinate/shikimate dehydrogenase from Corynebacterium glutamicum enable new insights in substrate and cofactor binding, specificity, and discrimination