scholarly journals A mixed-linkage (1,3;1,4)-β-D-glucan specific hydrolase mediates dark-triggered degradation of this plant cell wall polysaccharide

2021 ◽  
Author(s):  
Florian J Kraemer ◽  
China Lunde ◽  
Moritz Koch ◽  
Benjamin M Kuhn ◽  
Clemens Ruehl ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Large Scale ◽  
Plant Cell Wall ◽  
Causative Mutation ◽  
Grass Species ◽  
Calorie Intake ◽  
Cell Wall Polysaccharide ◽  
Transcript Accumulation

Abstract The presence of mixed-linkage (1,3;1,4)-β-D-glucan (MLG) in plant cell walls is a key feature of grass species such as cereals, the main source of calorie intake for humans and cattle. Accumulation of this polysaccharide involves the coordinated regulation of biosynthetic and metabolic machineries. While several components of the MLG biosynthesis machinery have been identified in diverse plant species, degradation of MLG is poorly understood. In this study, we performed a large-scale forward genetic screen for maize (Zea mays) mutants with altered cell wall polysaccharide structural properties. As a result, we identified a maize mutant with increased MLG content in several tissues, including adult leaves and senesced organs, where only trace amounts of MLG are usually detected. The causative mutation was found in the GRMZM2G137535 gene, encoding a GH17 licheninase as demonstrated by an in vitro activity assay of the heterologously expressed protein. In addition, maize plants overexpressing GRMZM2G137535 exhibit a 90% reduction in MLG content, indicating that the protein is not only required, but its expression is sufficient to degrade MLG. Accordingly, the mutant was named MLG hydrolase 1 (mlgh1). mlgh1 plants show increased saccharification yields upon enzymatic digestion. Stacking mlgh1 with lignin-deficient mutations results in synergistic increases in saccharification. Time profiling experiments indicate that wall MLG content is modulated during day/night cycles, inversely associated with MLGH1 transcript accumulation. This cycling is absent in the mlgh1 mutant, suggesting that the mechanism involved requires MLG degradation, which may in turn regulate MLGH1 gene expression.

scholarly journals Degradation of mixed-linkage (1,3;1,4)-β-D-glucan in maize is mediated by the CAL1 licheninase

2020 ◽  
Author(s):  
Florian J Kraemer ◽  
China Lunde ◽  
Moritz Koch ◽  
Benjamin M Kuhn ◽  
Clemens Ruehl ◽  
...  
Keyword(s):  
Cell Walls ◽  
Large Scale ◽  
Enzymatic Digestion ◽  
Causative Mutation ◽  
Grass Species ◽  
Calorie Intake ◽  
Cell Wall Polysaccharide ◽  
Transcript Accumulation ◽  
Altered Cell

The presence of mixed-linkage (1,3;1,4)-β-D-glucan (MLG) in plant cell walls is a key feature of grass species such as cereals - the main source of calorie intake for humans and cattle. Accumulation of this polysaccharide involves the coordinated regulation of biosynthetic and metabolic machineries. While several components of the MLG biosynthesis machinery have been identified in diverse plant species, degradation of MLG is poorly understood. A large-scale forward genetic maize screen for mutants with altered cell wall polysaccharide structural properties resulted in the identification of candy-leaf1 (cal1). Cell walls of CAL1-deficient plants contain higher amounts of MLG in several tissues, including adult leaves and senesced organs, where only trace amounts of MLG are usually detected. In addition, cal1 plants exhibit increased saccharification yields upon enzymatic digestion. Stacking cal1 with lignin-deficient mutations results in synergistic saccharification increases. Identification of the causative mutation revealed that CAL1 encodes a GH17 licheninase. Maize plants overexpressing CAL1 exhibit a 90% reduction in MLG content, indicating that CAL1 is not only required, but its expression sufficient to degrade MLG. CAL1 specifically hydrolyzes (1,3;1,4)-β-D-Glucans in vitro, and the single CAL1E262K amino acid substitution is able to block all detectable activity. Time profiling experiments indicate that wall MLG content is modulated during day/night cycles inversely correlating with CAL1 transcript accumulation. This cycling is absent in the cal1 mutant, suggesting that the mechanism involved requires MLG degradation that may in turn regulate CAL1 gene expression.

scholarly journals PUL-Mediated Plant Cell Wall Polysaccharide Utilization in the Gut Bacteroidetes

2021 ◽  
Vol 22 (6) ◽  
pp. 3077
Author(s):  
Zhenzhen Hao ◽  
Xiaolu Wang ◽  
Haomeng Yang ◽  
Tao Tu ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Microbial Community ◽  
Gut Microbiota ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Cell Wall Polysaccharide ◽  
Prominent Feature ◽  
Cell Wall Polysaccharides ◽  
Gut Microbial Community

Plant cell wall polysaccharides (PCWP) are abundantly present in the food of humans and feed of livestock. Mammalians by themselves cannot degrade PCWP but rather depend on microbes resident in the gut intestine for deconstruction. The dominant Bacteroidetes in the gut microbial community are such bacteria with PCWP-degrading ability. The polysaccharide utilization systems (PUL) responsible for PCWP degradation and utilization are a prominent feature of Bacteroidetes. In recent years, there have been tremendous efforts in elucidating how PULs assist Bacteroidetes to assimilate carbon and acquire energy from PCWP. Here, we will review the PUL-mediated plant cell wall polysaccharides utilization in the gut Bacteroidetes focusing on cellulose, xylan, mannan, and pectin utilization and discuss how the mechanisms can be exploited to modulate the gut microbiota.

scholarly journals The Role of Brachypodium distachyon Wall-Associated Kinases (WAKs) in Cell Expansion and Stress Responses

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2478
Author(s):  
Xingwen Wu ◽  
Antony Bacic ◽  
Kim L. Johnson ◽  
John Humphries
Keyword(s):  
Cell Wall ◽  
Stress Response ◽  
Plant Cell ◽  
Stress Responses ◽  
Cell Expansion ◽  
Plant Cell Wall ◽  
Brachypodium Distachyon ◽  
Critical Role ◽  
Cell Integrity

The plant cell wall plays a critical role in signaling responses to environmental and developmental cues, acting as both the sensing interface and regulator of plant cell integrity. Wall-associated kinases (WAKs) are plant receptor-like kinases located at the wall—plasma membrane—cytoplasmic interface and implicated in cell wall integrity sensing. WAKs in Arabidopsis thaliana have been shown to bind pectins in different forms under various conditions, such as oligogalacturonides (OG)s in stress response, and native pectin during cell expansion. The mechanism(s) WAKs use for sensing in grasses, which contain relatively low amounts of pectin, remains unclear. WAK genes from the model monocot plant, Brachypodium distachyon were identified. Expression profiling during early seedling development and in response to sodium salicylate and salt treatment was undertaken to identify WAKs involved in cell expansion and response to external stimuli. The BdWAK2 gene displayed increased expression during cell expansion and stress response, in addition to playing a potential role in the hypersensitive response. In vitro binding assays with various forms of commercial polysaccharides (pectins, xylans, and mixed-linkage glucans) and wall-extracted fractions (pectic/hemicellulosic/cellulosic) from both Arabidopsis and Brachypodium leaf tissues provided new insights into the binding properties of BdWAK2 and other candidate BdWAKs in grasses. The BdWAKs displayed a specificity for the acidic pectins with similar binding characteristics to the AtWAKs.

scholarly journals Direct evidence for a new mode of plant defense against insects via a novel polygalacturonase-inhibiting protein expression strategy

2020 ◽  
Vol 295 (33) ◽  
pp. 11833-11844
Author(s):  
Wiebke Haeger ◽  
Jana Henning ◽  
David G. Heckel ◽  
Yannick Pauchet ◽  
Roy Kirsch
Keyword(s):  
Cell Wall ◽  
Plant Defense ◽  
Plant Cell Wall ◽  
Direct Evidence ◽  
Larval Growth ◽  
Gene Families ◽  
Preliminary Evidence ◽  
Cell Wall Polysaccharide ◽  
In Planta

Plant cell wall–associated polygalacturonase-inhibiting proteins (PGIPs) are widely distributed in the plant kingdom. They play a crucial role in plant defense against phytopathogens by inhibiting microbial polygalacturonases (PGs). PGs hydrolyze the cell wall polysaccharide pectin and are among the first enzymes to be secreted during plant infection. Recent studies demonstrated that herbivorous insects express their own PG multi-gene families, raising the question whether PGIPs also inhibit insect PGs and protect plants from herbivores. Preliminary evidence suggested that PGIPs may negatively influence larval growth of the leaf beetle Phaedon cochleariae (Coleoptera: Chrysomelidae) and identified BrPGIP3 from Chinese cabbage (Brassica rapa ssp. pekinensis) as a candidate. PGIPs are predominantly studied in planta because their heterologous expression in microbial systems is problematic and instability and aggregation of recombinant PGIPs has complicated in vitro inhibition assays. To minimize aggregate formation, we heterologously expressed BrPGIP3 fused to a glycosylphosphatidylinositol (GPI) membrane anchor, immobilizing it on the extracellular surface of insect cells. We demonstrated that BrPGIP3_GPI inhibited several P. cochleariae PGs in vitro, providing the first direct evidence of an interaction between a plant PGIP and an animal PG. Thus, plant PGIPs not only confer resistance against phytopathogens, but may also aid in defense against herbivorous beetles.

Structural properties and foaming of plant cell wall polysaccharide dispersions

2017 ◽  
Vol 173 ◽  
pp. 508-518 ◽  
Author(s):  
Cesar A.G. Beatrice ◽  
Natalia Rosa-Sibakov ◽  
Martina Lille ◽  
Nesli Sözer ◽  
Kaisa Poutanen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Structural Properties ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Cell Wall Polysaccharide

scholarly journals Fermentation and subsequent disposition of 14C-labelled plant cell wall material in the rat

1993 ◽  
Vol 69 (1) ◽  
pp. 189-197 ◽  
Author(s):  
D. F. Gray ◽  
M. A. Eastwood ◽  
W. G. Brydon ◽  
S. C. Fry
Keyword(s):  
Cell Wall ◽  
Gastrointestinal Tract ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Spinacia Oleracea ◽  
Wall Material ◽  
Fermentation Products ◽  
Bacterial Fermentation ◽  
Cell Wall Preparation

A 14C-Iabelled plant cell wall preparation (I4C-PCW) produced from spinach (Spinacia oleracea L.) cell culture exhibits uniform labelling of the major polysaccharide groups (%): pectins 53, hemicellulose 13, cellulose 21, starch 3. This 14C-PCW preparation has been used in rat studies as a marker for plant cell wall metabolism. Metabolism of the 14C-PCW occurred largely over the first 24 h. This was due to fermentation in the caecum. The pectic fraction of the plant cell walls was degraded completely in the rat gastrointestinal tract, but some [14C-]cellulose was still detected after 24 h in the colon. Of the 14C,22% was recovered in the host liver, adipose tissue and skin, 26% excreted as 14CO2 and up to 18%was excreted in the faeces. There was no urinary excretion of 14C. In vitro fermentation using a caecal inocuium showed reduced 14CO2 production, 12% compared with 26% in the intact rat. 14C-PCW is auseful marker to investigate the fate of plant cell wall materials in the gastrointestinal tract. These studies show both bacterial fermentation of the 14C-PCW and host metabolism of the 14C-labelled fermentation products.

Hierarchical architecture of bacterial cellulose and composite plant cell wall polysaccharide hydrogels using small angle neutron scattering

Soft Matter ◽  
2016 ◽  
Vol 12 (5) ◽  
pp. 1534-1549 ◽  
Author(s):  
Marta Martínez-Sanz ◽  
Michael J. Gidley ◽  
Elliot P. Gilbert
Keyword(s):  
Cell Wall ◽  
Bacterial Cellulose ◽  
Plant Cell ◽  
Small Angle Neutron Scattering ◽  
Plant Cell Wall ◽  
Solvent Accessibility ◽  
Hierarchical Architecture ◽  
Cell Wall Polysaccharide ◽  
Cell Wall Polysaccharides ◽  
Sans Data

SANS data of bacterial cellulose and its composites with plant cell wall polysaccharides can be described by a core–shell model which accounts for the distinct solvent accessibility to the ribbons' inner/outer regions.

scholarly journals Immunocytochemical Localization of HrpA and HrpZ Supports a Role for the Hrp Pilus in the Transfer of Effector Proteins from Pseudomonas syringae pv. tomato Across the Host Plant Cell Wall

2001 ◽  
Vol 14 (3) ◽  
pp. 394-404 ◽  
Author(s):  
Ian R. Brown ◽  
John W. Mansfield ◽  
Suvi Taira ◽  
Elina Roine ◽  
Martin Romantschuk
Keyword(s):  
Cell Wall ◽  
Pseudomonas Syringae ◽  
Plant Cell ◽  
Type Iii Secretion ◽  
Plant Cell Wall ◽  
Immunogold Labeling ◽  
Effector Proteins ◽  
Basal Bodies ◽  
Type Iii

The Hrp pilus, composed of HrpA subunits, is an essential component of the type III secretion system in Pseudomonas syringae. We used electron microscopy (EM) and immunocytochemistry to examine production of the pilus in vitro from P. syringae pv. tomato strain DC3000 grown under hrp-inducing conditions on EM grids. Pili, when labeled with antibodies to HrpA, developed rapidly in a nonpolar manner shortly after the detection of the hrpA transcript and extended up to 5 μm into surrounding media. Structures at the base of the pilus were clearly differentiated from the basal bodies of flagella. The HrpZ protein, also secreted via the type III system, was found by immunogold labeling to be associated with the pilus in vitro. Accumulation and secretion of HrpA and HrpZ were also examined quantitatively after the inoculation of wild-type DC3000 and hrpA and hrpZ mutants into leaves of Arabidopsis thaliana. The functional pilus crossed the plant cell wall to generate tracks of immunogold labeling for HrpA and HrpZ. Mutants that produced HrpA but did not assemble pili were nonpathogenic, did not secrete HrpA protein, and were compromised for the accumulation of HrpZ. A model is proposed in which the rapidly elongating Hrp pilus acts as a moving conveyor, facilitating transfer of effector proteins from bacteria to the plant cytoplasm across the formidable barrier of the plant cell wall.

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