scholarly journals Changes in enzymic activities of nucleoside diphosphate sugar interconversions during differentiation of cambium to xylem in pine and fir

1977 ◽  
Vol 162 (2) ◽  
pp. 281-288 ◽  
Author(s):  
G Dalessandro ◽  
D H Northcote
Keyword(s):  
Cell Wall ◽  
Protein Fraction ◽  
Glucuronic Acid ◽  
Glucose Dehydrogenase ◽  
Preceding Paper ◽  
Polysaccharide Synthesis ◽  
Cell Wall Development ◽  
Specific Activities ◽  
Cambial Cells

A protein fraction [precipitate obtained between 40 and 65% (NH4)2SO4 satn.] prepared from cambial cells, differentiating xylem cells and differentiated xylem cells of pine and fir trees contained all the enzymes required for the nucleoside diphosphate sugar interconversions. By using UDP-D-[U-14C]glucose or UDP-D-[U-14C]galactose, UDP-D-[U-14C-]glucuronic acid and UDP-D-[U-14C]xylose as substrates, the activities of UDP-D-galactose 4-epimerase (DC 5.1.3.2), UDP-D-xylose 4-epimerase(EC 5.1.3.5), UDP-D-glucose dehydrogenase (EC 1.1.1.22) and UDP-D-glucuronate 4-epimerase (EC5.1.3.6), UDP-d-glucuronate decarboxylase (EC 4.1.1.35) were measured at different stages of cell-wall development. The specific activities and the activities per cell of these enzymes varied during differentiation of cambium to xylem according to the type polysaccharide synthesized. Variations were also found between the two species investigated. These data, compared with those obtained in out previous work on angiosperms [see the preceding paper, Dalessandro & Northcote (1977) Biochem. J. 162, 267-279], suggest that some control of polysaccharide synthesis operates at the level of the formation of the precursors of pectin and hemicellulose syntheses.

scholarly journals UDP-glucose dehydrogenases of maize: a role in cell wall pentose biosynthesis

2005 ◽  
Vol 391 (2) ◽  
pp. 409-415 ◽  
Author(s):  
Anna Kärkönen ◽  
Alain Murigneux ◽  
Jean-Pierre Martinant ◽  
Elodie Pepey ◽  
Christophe Tatout ◽  
...  
Keyword(s):  
Cell Wall ◽  
Sequence Similarity ◽  
Glucose Dehydrogenase ◽  
Soya Bean ◽  
Amino Acid Sequences ◽  
Cell Wall Polysaccharide ◽  
Polysaccharide Biosynthesis ◽  
Polysaccharide Synthesis ◽  
Ethanol Dehydrogenase ◽  
Adh Activity

UDPGDH (UDP-D-glucose dehydrogenase) oxidizes UDP-Glc (UDP-D-glucose) to UDP-GlcA (UDP-D-glucuronate), the precursor of UDP-D-xylose and UDP-L-arabinose, major cell wall polysaccharide precursors. Maize (Zea mays L.) has at least two putative UDPGDH genes (A and B), according to sequence similarity to a soya bean UDPGDH gene. The predicted maize amino acid sequences have 95% similarity to that of soya bean. Maize mutants with a Mu-element insertion in UDPGDH-A or UDPGDH-B were isolated (udpgdh-A1 and udpgdh-B1 respectively) and studied for changes in wall polysaccharide biosynthesis. The udpgdh-A1 and udpgdh-B1 homozygotes showed no visible phenotype but exhibited 90 and 60–70% less UDPGDH activity respectively than wild-types in a radiochemical assay with 30 μM UDP-glucose. Ethanol dehydrogenase (ADH) activity varied independently of UDPGDH activity, supporting the hypothesis that ADH and UDPGDH activities are due to different enzymes in maize. When extracts from wild-types and udpgdh-A1 homozygotes were assayed with increasing concentrations of UDP-Glc, at least two isoforms of UDPGDH were detected, having Km values of approx. 380 and 950 μM for UDP-Glc. Leaf and stem non-cellulosic polysaccharides had lower Ara/Gal and Xyl/Gal ratios in udpgdh-A1 homozygotes than in wild-types, whereas udpgdh-B1 homozygotes exhibited more variability among individual plants, suggesting that UDPGDH-A activity has a more important role than UDPGDH-B in UDP-GlcA synthesis. The fact that mutation of a UDPGDH gene interferes with polysaccharide synthesis suggests a greater importance for the sugar nucleotide oxidation pathway than for the myo-inositol pathway in UDP-GlcA biosynthesis during post-germinative growth of maize.

scholarly journals UGD1, Encoding the Cryptococcus neoformans UDP-Glucose Dehydrogenase, Is Essential for Growth at 37°C and for Capsule Biosynthesis

2004 ◽  
Vol 3 (6) ◽  
pp. 1601-1608 ◽  
Author(s):  
Frédérique Moyrand ◽  
Guilhem Janbon
Keyword(s):  
Cell Wall ◽  
Sodium Dodecyl Sulfate ◽  
Cryptococcus Neoformans ◽  
Virulence Factors ◽  
Biosynthetic Pathway ◽  
Glucuronic Acid ◽  
Glucose Dehydrogenase ◽  
Sodium Dodecyl ◽  
Gene Encoding ◽  
Common Cell

ABSTRACT We report the identification and disruption of the Cryptococcus neoformans var. grubii UGD1 gene encoding the UDP-glucose dehydrogenase, which catalyzes the conversion of UDP-glucose into UDP-glucuronic acid. Deletion of UGD1 led to modifications in the cell wall, as revealed by changes in the sensitivity of ugd1Δ cells to sodium dodecyl sulfate, NaCl, and sorbitol. Moreover, two of the yeast's major virulence factors—capsule biosynthesis and the ability to grow at 37°C—were impaired in ugd1Δ strains. These results suggest that the UDP-dehydrogenase represents the major, and maybe only, biosynthetic pathway for UDP-glucuronic acid in C. neoformans. Consequently, deletion of UGD1 blocked not only the synthesis of UDP-glucuronic acid but also that of UDP-xylose. To differentiate the phenotype(s) associated with the UDP-glucuronic acid defect alone from those linked to the UDP-xylose defect, ugd1Δ mutants were phenotypically compared to strains from which the gene encoding UDP-xylose synthase (i.e., that required for synthesis of UDP-xylose) had been deleted. Finally, studies of strains from which one of the four CAP genes (CAP10, CAP59, CAP60, or CAP64) had been deleted revealed common cell wall phenotypes associated with the acapsular state.

scholarly journals The biosynthesis of tyramine glucuronide by liver microsomal fractions

1977 ◽  
Vol 164 (3) ◽  
pp. 529-531 ◽  
Author(s):  
K P Wong
Keyword(s):  
Monoamine Oxidase ◽  
Guinea Pig ◽  
Glucuronic Acid ◽  
Monoamine Oxidase Inhibitor ◽  
Oxidase Inhibitor ◽  
Freezing And Thawing ◽  
Monkey Liver ◽  
Specific Activities ◽  
Low Activity

Labelled tyramine glucuronide was synthesized in vitro from UDP-[14C]glucuronic acid, [14C]tyramine or [3H]tyramine. The glucuronidation was carried out at pH9.2 in the presence of a monoamine oxidase inhibitor, trans-2-phenylcyclopropylamine. The Km values for tyramine were 69 and 125 micrometer and those for UDP-glucuronic acid were 260 and 290 micrometer respectively for guinea-pig and rat liver microsomal preparatons. The specific activities of microsomal glucuronyltransferase measured in fresh hepatic preparations of guinea pig, mouse and rat were respectively 601, 251 and 235 pmol of [14C]tyramine glucuronide/min per mg of protein. Increase in activity ranged from 2- to 6-fold in preparations which were frozen and thawed once and 5.4- to 10-fold when the freezing and thawing was repeated. Rabbit liver has very low activity, and monkey liver and intestine were completely devoid of this conjugating capacity.

scholarly journals An NAC transcription factor orchestrates multiple features of cell wall development in Medicago truncatula

2010 ◽  
pp. no-no ◽  
Author(s):  
Qiao Zhao ◽  
Lina Gallego-Giraldo ◽  
Huanzhong Wang ◽  
Yining Zeng ◽  
Shi-You Ding ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Medicago Truncatula ◽  
Nac Transcription Factor ◽  
Multiple Features ◽  
Cell Wall Development

Radioautographic and Chemical Studies of Incorporation into Sycamore Vascular Tissue Walls

1968 ◽  
Vol 3 (1) ◽  
pp. 71-80
Author(s):  
F. B. P. WOODING
Keyword(s):  
Cell Wall ◽  
Vascular Tissue ◽  
Golgi Body ◽  
Cell Wall Polysaccharide ◽  
Polysaccharide Synthesis ◽  
Chemical Studies

Chemical and radioautographic studies on sycamore seedling stems have shown an involvement of the Golgi body in cell-wall polysaccharide synthesis from tritiated glucose. Tritiated phenylalanine is shown to be incorporated only into lignin after short incubation times. The patterns of labelling are compared and discussed for the two precursors.

THE BIOSYNTHESIS OF CELL WALL CARBOHYDRATES: III. FURTHER STUDIES ON FORMATION OF CELLULOSE AND XYLAN FROM LABELED MONOSACCHARIDES IN WHEAT PLANTS

1956 ◽  
Vol 34 (1) ◽  
pp. 405-413 ◽  
Author(s):  
H. A. Altermatt ◽  
A. C. Neish
Keyword(s):  
Cell Wall ◽  
Leuconostoc Mesenteroides ◽  
Carbon Skeleton ◽  
The Other ◽  
Uridine Diphosphate ◽  
Uridine Diphosphate Glucose ◽  
Polysaccharide Synthesis ◽  
Diphosphate Glucose ◽  
Cell Wall Carbohydrates

D-Glucose-1-C14, D-glucose-2-C14, D-xylose-2-C14, D-xylose-5-C14, D-arabinose-1-C14, D-glucuronolactone-1-C14, D-glucitol-1-C14, D-mannitol-1-C14, D-arabitol-1-C14, and D-arabitol-5-C14 were administered to wheat plants. The cellulose and xylan were isolated after a period of metabolism varying from 2 to 23 hr. D-Mannitol and D-arabitol were not converted to either cellulose or xylan while D-arabinose was utilized slightly. The other compounds gave rise to both labelled cellulose and xylan. The glucose and xylose, obtained from the cellulose and xylan respectively, were degraded by fermentation with Leuconostoc mesenteroides. Glucose and glucuronolactone were equally good precursors of xylan and were superior to the other compounds tried. They appeared to give rise to units for xylan formation by loss of carbon-6. Free xylose was converted to xylan units only after an extensive rearrangement of the carbon skeleton, such as occurred in the conversion of xylose to cellulose units. A hypothetical outline of polysaccharide synthesis, involving uridine diphosphate glucose as the central intermediate, is suggested to explain the data.

A DFT study on the catalytic mechanism of UDP-glucose dehydrogenase

2010 ◽  
Vol 88 (8) ◽  
pp. 804-814 ◽  
Author(s):  
WenJuan Huang ◽  
Jorge Llano ◽  
James W. Gauld
Keyword(s):  
Pathogenic Bacteria ◽  
Catalytic Mechanism ◽  
Glucuronic Acid ◽  
Glucose Dehydrogenase ◽  
Polarizable Continuum Model ◽  
Uridine Diphosphate ◽  
Reaction Field ◽  
Enzyme Active Site ◽  
Site Model ◽  
Diphosphate Glucose

Uridine 5′-diphosphate glucuronic acid (UDPGlcUA) is a key intermediary metabolite in many species, including pathogenic bacteria and humans. It is biosynthesized from UDP-glucose (UDPGlc) by uridine diphosphate glucose dehydrogenase (UDPGlcDH) via a twofold two-electron–one-proton oxidation that successively transforms the 6-hydroxymethyl of glucopyranose into a formyl, and the latter into the final carboxylic function. The catalytic mechanism of UDPGlcDH was investigated using a large enzyme active-site model in combination with the B3LYP method and the polarizable continuum model (IEF-PCM) self-consistent reaction field. The latter was used to correct for the long-range electrostatic effect of the protein environment. The overall mechanism consists of four catalytic steps: (i) NAD+-dependent oxidation of glucose to glucuronaldehyde, (ii) nucleophilic addition of Cys260–SH to glucuronaldehyde to form a 6-thiohemiacetal intermediate, (iii) NAD+-dependent oxidation of the 6-thiohemiacetal to form a 6-thioester intermediate, and finally, (iv) hydrolysis of the 6-thioester to give glucuronic acid. In addition, this study also provides insight into the debated roles of Lys204 and Asp264, and the most likely protonation state of a reactive Michaelis complex of UDPGlcDH.

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