Cell Wall Polysaccharide Synthesis

Mohnen, Debra; Bar‐Peled, Maor; Somerville, Chris

doi:10.1002/9781444305418.ch5

Cited by 52 publications

(46 citation statements)

References 384 publications

(643 reference statements)

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“…These proteins contain two conserved motifs that are also common in other NDP-sugar interconverting enzymes such as 4,6-dehydratases, and 4-epimerases (24). At the N-terminal region of these proteins is the GXXGXXG domain that binds the cofactor NAD ϩ (25), and ϳ100 amino acids downstream is the YXXXK motif (26) that is involved in catalysis.…”

Section: Resultsmentioning

confidence: 99%

Identification of a Bifunctional UDP-4-keto-pentose/UDP-xylose Synthase in the Plant Pathogenic Bacterium Ralstonia solanacearum Strain GMI1000, a Distinct Member of the 4,6-Dehydratase and Decarboxylase Family

Glushka

Yin

et al. 2010

Journal of Biological Chemistry

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The UDP-sugar interconverting enzymes involved in UDPGlcA metabolism are well described in eukaryotes but less is known in prokaryotes. Here we identify and characterize a gene (RsU4kpxs) from Ralstonia solanacearum str. GMI1000, which encodes a dual function enzyme not previously described. One activity is to decarboxylate UDP-glucuronic acid to UDP-␤-Lthreo-pentopyranosyl-4؆-ulose in the presence of NAD ؉ . The second activity converts UDP-␤-L-threo-pentopyranosyl-4؆-ulose and NADH to UDP-xylose and NAD ؉ , albeit at a lower rate. Our data also suggest that following decarboxylation, there is stereospecific protonation at the C5 pro-R position. The identification of the R. solanacearum enzyme enables us to propose that the ancestral enzyme of UDP-xylose synthase and UDP-apiose/UDP-xylose synthase was diverged to two distinct enzymatic activities in early bacteria. This separation gave rise to the current UDP-xylose synthase in animal, fungus, and plant as well as to the plant Uaxs and bacterial ArnA and U4kpxs homologs.

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Section: Resultsmentioning

confidence: 99%

Identification of a Bifunctional UDP-4-keto-pentose/UDP-xylose Synthase in the Plant Pathogenic Bacterium Ralstonia solanacearum Strain GMI1000, a Distinct Member of the 4,6-Dehydratase and Decarboxylase Family

Glushka

Yin

et al. 2010

Journal of Biological Chemistry

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“…Hemicelluloses constitute significant proportions of plant biomass polysaccharides, between one-quarter and one-half of the mass of many types of cell walls, and they vary tremendously depending upon the plant species and tissue type (34). The four main kinds of hemicelluloses are xyloglucan, xylans, mixed-linkage glucans, and mannans, which contain different backbones with various side groups, bonds, degrees of branching, and polymerization.…”

Section: Discussionmentioning

confidence: 99%

LacI Transcriptional Regulatory Networks in Clostridium thermocellum DSM1313

Wilson

Klingeman

Schlachter

et al. 2017

Appl Environ Microbiol

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Organisms regulate gene expression in response to the environment to coordinate metabolic reactions. Clostridium thermocellum expresses enzymes for both lignocellulose solubilization and its fermentation to produce ethanol. One LacI regulator termed GlyR3 in C. thermocellum ATCC 27405 was previously identified as a repressor of neighboring genes with repression relieved by laminaribiose (a ␤-1,3 disaccharide). To better understand the three C. thermocellum LacI regulons, deletion mutants were constructed using the genetically tractable DSM1313 strain. DSM1313 lacI genes Clo1313_2023, Clo1313_0089, and Clo1313_0396 encode homologs of GlyR1, GlyR2, and GlyR3 from strain ATCC 27405, respectively. Growth on cellobiose or pretreated switchgrass was unaffected by any of the gene deletions under controlled-pH fermentations. Global gene expression patterns from time course analyses identified glycoside hydrolase genes encoding hemicellulases, including cellulosomal enzymes, that were highly upregulated (5-to 100-fold) in the absence of each LacI regulator, suggesting that these were repressed under wild-type conditions and that relatively few genes were controlled by each regulator under the conditions tested. Clo1313_2022, encoding lichenase enzyme LicB, was derepressed in a ΔglyR1 strain. Higher expression of Clo1313_1398, which encodes the Man5A mannanase, was observed in a ΔglyR2 strain, and ␣-mannobiose was identified as a probable inducer for GlyR2-regulated genes. For the ΔglyR3 strain, upregulation of the two genes adjacent to glyR3 in the celC-glyR3-licA operon was consistent with earlier studies. Electrophoretic mobility shift assays have confirmed LacI transcription factor binding to specific regions of gene promoters. IMPORTANCE Understanding C. thermocellum gene regulation is of importance for improved fundamental knowledge of this industrially relevant bacterium. Most LacI transcription factors regulate local genomic regions; however, a small number of those genes encode global regulatory proteins with extensive regulons. This study indicates that there are small specific C. thermocellum LacI regulons. The identification of LacI repressor activity for hemicellulase gene expression is a key result of this work and will add to the small body of existing literature on the area of gene regulation in C. thermocellum.

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“…Plant cell wall materials are also important sources of human and animal nutrition, natural textile fibers, paper and wood products, and raw materials for biofuel production (Somerville, 2007). Many genes thought to be responsible for plant wall biosynthesis and modification have been identified (Burton et al, 2005;Lerouxel et al, 2006;Mohnen et al, 2008), and 15% of the Arabidopsis (Arabidopsis thaliana) genome is likely devoted to these functions (Carpita et al, 2001). However, phenotypic analysis in plants carrying cell wall-related mutations has proven particularly difficult.…”

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confidence: 99%

A Comprehensive Toolkit of Plant Cell Wall Glycan-Directed Monoclonal Antibodies

et al. 2010

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A collection of 130 new plant cell wall glycan-directed monoclonal antibodies (mAbs) was generated with the aim of facilitating in-depth analysis of cell wall glycans. An enzyme-linked immunosorbent assay-based screen against a diverse panel of 54 plant polysaccharides was used to characterize the binding patterns of these new mAbs, together with 50 other previously generated mAbs, against plant cell wall glycans. Hierarchical clustering analysis was used to group these mAbs based on the polysaccharide recognition patterns observed. The mAb groupings in the resulting cladogram were further verified by immunolocalization studies in Arabidopsis (Arabidopsis thaliana) stems. The mAbs could be resolved into 19 clades of antibodies that recognize distinct epitopes present on all major classes of plant cell wall glycans, including arabinogalactans (both protein-and polysaccharide-linked), pectins (homogalacturonan, rhamnogalacturonan I), xyloglucans, xylans, mannans, and glucans. In most cases, multiple subclades of antibodies were observed to bind to each glycan class, suggesting that the mAbs in these subgroups recognize distinct epitopes present on the cell wall glycans. The epitopes recognized by many of the mAbs in the toolkit, particularly those recognizing arabinose-and/or galactose-containing structures, are present on more than one glycan class, consistent with the known structural diversity and complexity of plant cell wall glycans. Thus, these cell wall glycan-directed mAbs should be viewed and utilized as epitope-specific, rather than polymer-specific, probes. The current world-wide toolkit of approximately 180 glycan-directed antibodies from various laboratories provides a large and diverse set of probes for studies of plant cell wall structure, function, dynamics, and biosynthesis.

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Cell Wall Polysaccharide Synthesis

Cited by 52 publications

References 384 publications

Identification of a Bifunctional UDP-4-keto-pentose/UDP-xylose Synthase in the Plant Pathogenic Bacterium Ralstonia solanacearum Strain GMI1000, a Distinct Member of the 4,6-Dehydratase and Decarboxylase Family

Identification of a Bifunctional UDP-4-keto-pentose/UDP-xylose Synthase in the Plant Pathogenic Bacterium Ralstonia solanacearum Strain GMI1000, a Distinct Member of the 4,6-Dehydratase and Decarboxylase Family

LacI Transcriptional Regulatory Networks in Clostridium thermocellum DSM1313

A Comprehensive Toolkit of Plant Cell Wall Glycan-Directed Monoclonal Antibodies

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