Sugar Nucleotide Transformations in Plants

Feingold, David S.; Avigad, Gad

doi:10.1016/b978-0-12-675403-2.50010-7

Cited by 81 publications

(76 citation statements)

References 397 publications

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“…2.7.1.4; FK) catalyze the initial step in the metabolism of plant hexoses, which is phosphorylation by ATP. HEX is thought to be responsible for the phosphorylation of glucose and mannose, while FK primarily phosphorylates fructose (Feingold and Avigad 1980;Turner et al 1977 a, b;Turner and Copeland 1981).…”

Section: Introductionmentioning

confidence: 99%

Duplicated chromosome segments in maize (Zea mays L.): further evidence from hexokinase isozymes

Wendel

Stuber

Edwards

et al. 1986

Theoret. Appl. Genetics

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The genetic control of hexokinase isozymes (ATP: d-hexose-6-phosphotransferase, E.C. 2.7.7.1, HEX) in maize (Zea mays L.) was studied by starch gel electrophoresis. Genetic analysis of a large number of inbred lines and crosses indicates that the major isozymes observed are encoded by two nuclear loci, designated Hexl and Hex2. Five active allozymes and one null variant are associated with Hexl, while Hex2 has nine active alleles in addition to a null variant. Alleles at both loci govern the presence of single bands, with no intragenic or intergenic heteromers visible, suggesting that maize HEX's are active as monomers. Organelle preparations demonstrate that the products of both loci are cytosolic. All alleles, including the nulls, segregate normally in crosses. Vigorous and fertile plants were synthesized that were homozygous for null alleles at both loci, suggesting that other hexosephosphorylating enzymes exist in maize that are undetected with our assay conditions. Linkage analyses and crosses with B-A translocation stocks place Hexl on the short arm of chromosome 3, 27 centimorgans from Pgd2 (phosphogluconate dehydrogenase) and Hex2 on the long arm of chromosome 6, approximately 45 centimorgans from Pgdl. It is suggested that the parallel linkages among these two pairs of duplicated genes reflects an evolutionary history involving chromosome segment duplication or polyploidy. d-hexose-6-phosphotransferase, E.C. 2.7.7.1, flEX) in maize (Zea mays L.) was studied by starch gel electrophoresis. Genetic analysis of a large number of inbred lines and crosses indicates that the major isozymes observed are encoded by two nuclear loci, designated Hexl and Hex2. Five active allozymes and one null variant are associated with Hexl, while Hex2 has nine active alleles in addition to a null variant. Alleles at both loci govern the presence of single bands, with no intragenic or intergenic heteromers visible, suggesting that maize HEX's are active as monomers. Organelle preparations demonstrate that the products of both loci are cytosolic. All alleles, including the nulls, segregate normally in crosses. Vigorous and fertile plants were synthesized that were homozygous for null alleles at both loci, suggesting that other hexosephosphorylating enzymes exist in maize that are undetected with our assay conditions. Linkage analyses and crosses with B-A translocation stocks place Hexl on the short arm of chromosome 3, 27 centimorgans from Pgd2 (phosphogluconate dehydrogenase) and Hex2 on the long arm of chromosome 6, approximately 45 centimorgans from Pgdl. It is suggested that the parallel linkages among these two pairs of duplicated genes reflects an evolutionary history involving chromosome segment duplication or polyploidy.

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Section: Introductionmentioning

confidence: 99%

Duplicated chromosome segments in maize (Zea mays L.): further evidence from hexokinase isozymes

Wendel

Stuber

Edwards

et al. 1986

Theoret. Appl. Genetics

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“…The reversible interconversion of UDP-Xyl and UDP-Ara is catalyzed by UDP-D-xylose 4-epimerase (UXE; Feingold and Avigad, 1980). Epimerases of this type are believed to require a noncovalently bound NAD + cofactor (Schutzbach and Feingold, 1970).…”

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confidence: 99%

“…UDPAra is also an important sugar donor for arabinogalactan proteins and pectic polysaccharides (Feingold and Avigad, 1980;Reiter and Vanzin, 2001). The UDPXyl and UDP-Ara substrates are drawn from a pool of sugar nucleotides that originate primarily from UDP-D-Glc (UDP-Glc), although there are a number of pathways involved (Sharples and Fry, 2007).…”

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confidence: 99%

The Genetics, Transcriptional Profiles, and Catalytic Properties of UDP-α-d-Xylose 4-Epimerases from Barley

et al. 2010

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Cell walls in the grasses contain relatively high levels of heteroxylans and, in particular, arabinoxylans. Enzymes and corresponding genes that are involved in the provision of sugar nucleotide substrates represent potential control points for arabinoxylan biosynthesis. Following expressed sequence tag database analyses, three genes encoding barley (Hordeum vulgare) UDP-D-xylose 4-epimerases (UXE; EC 5.1.3.5), designated HvUXE1, HvUXE2, and HvUXE3, were cloned and their positions on genetic maps defined. To confirm the identity of the genes, a cDNA construct encoding HvUXE1 was expressed in Pichia pastoris. The purified, recombinant HvUXE1 catalyzed the freely reversible interconversion of UDP-a-D-xylopyranose and UDP-b-L-arabinopyranose, with K m values of 1.8 and 1.4 mM, respectively. At equilibrium, the ratio of substrate to product was approximately 1:1. Each molecule of heterologously expressed HvUXE1 enzyme contained about one molecule of noncovalently bound NAD + . Molecular modeling provided a structural rationale for the substrate specificity of the UDP-D-xylose 4-epimerase and, in particular, explained its tight specificity for UDP-xylose compared with other sugar nucleotide epimerases. Quantitative transcript analyses performed for each of the three genes in a range of organs showed, inter alia, that in developing barley endosperm HvUXE1 and HvUXE3 mRNA levels peaked at a time when UDP-a-D-xylopyranose synthase (UXS) transcripts also reached a maximum and when arabinoxylan biosynthesis was initiated. Furthermore, the data revealed that the transcription of HvUXE and HvUXS gene family members is coordinated with the incorporation of pentose sugars onto cell walls in barley leaves, roots, and developing endosperm.

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“…L-Gal is a relatively rare sugar; it was found as a constituent of structural polysaccharides in some invertebrates (13,14) and in algae (15). On the contrary, in plants, L-Gal seems to be only a minor structural component, if any (9). It is apparently absent from cell-wall polysaccharides (16) as well as from glycoproteins (17) of wild-type Arabidopsis thaliana, but it could be detected as a substituent of L-Fuc in xyloglucans (18) and in a minor portion of N-glycans (17) of Arabidopsis mur1 mutants, which are known to be deficient in the first enzyme of the GDP-L-Fuc pathway, the GDP-Man 4Љ,6Љ-dehydratase (19).…”

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confidence: 99%

“…D-arabinose and D-arabinono-1,4-lactone are 5-carbon homologs of L-Gal and L-galactono-1,4-lactone, respectively. L-Gal was found in algae and plants, and the corresponding sugar nucleotide, GDP-L-Gal, is known to be formed from GDP-Man as a result of the 3Љ,5Љ-epimerization reaction (9). According to this line of evidence, Wheeler et al (10) demonstrated an efficient conversion of exogenous D-[ 14 C]Man and of cold L-Gal into L-AA, and the presence, by analogy with the yeast D-arabinose dehydrogenase, of L-Gal dehydrogenase activity in pea.…”

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confidence: 99%

Partial purification and identification of GDP-mannose 3",5"-epimerase of Arabidopsis thaliana , a key enzyme of the plant vitamin C pathway

Wolucka

Persiau

Doorsselaere

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

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The first step in the biosynthetic pathway of vitamin C in plants is the formation, at the level of sugar nucleotide, of L-galactosyl residues, catalyzed by a largely unknown GDP-D-mannose 3؆,5؆-epimerase. By using combined conventional biochemical and mass spectrometry methods, we obtained a highly purified preparation of GDP-D-mannose 3؆,5؆-epimerase from an Arabidopsis thaliana cell suspension. The native enzyme is an 84-kDa dimer, composed of two apparently identical subunits. In-gel tryptic digestion of the enzyme subunit, followed by peptide sequencing and a BLAST search, led to the identification of the epimerase gene. The closest homolog of the plant epimerase is the BlmG gene product of Streptomyces sp., a putative NDP-D-mannose 5؆-epimerase. The plant GDP-D-mannose 3؆,5؆-epimerase is, to our knowledge, a novel member of the extended short-chain dehydrogenase͞reductase family. The enzyme was cloned and expressed in Escherichia coli cells.

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Sugar Nucleotide Transformations in Plants

Cited by 81 publications

References 397 publications

Duplicated chromosome segments in maize (Zea mays L.): further evidence from hexokinase isozymes

Duplicated chromosome segments in maize (Zea mays L.): further evidence from hexokinase isozymes

The Genetics, Transcriptional Profiles, and Catalytic Properties of UDP-α-d-Xylose 4-Epimerases from Barley

Partial purification and identification of GDP-mannose 3",5"-epimerase of Arabidopsis thaliana , a key enzyme of the plant vitamin C pathway

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