scholarly journals The Gene Encoding NAD-Dependent Epimerase/Dehydratase, wcaG, Affects Cell Surface Properties, Virulence, and Extracellular Enzyme Production in the Soft Rot Phytopathogen, Pectobacterium carotovorum

2019 ◽  
Vol 7 (6) ◽  
pp. 172 ◽  
Author(s):  
Rabiul Islam ◽  
Shyretha Brown ◽  
Ali Taheri ◽  
C. Korsi Dumenyo
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Cell Surface ◽  
Surface Properties ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Soft Rot ◽  
Pectobacterium Carotovorum ◽  
Cell Wall Degrading Enzymes ◽  
Cell Surface Properties

Pectobacterium carotovorum is a gram-negative bacterium that, together with other soft rot Enterobacteriaceae causes soft rot disease in vegetables, fruits, and ornamental plants through the action of exoproteins including plant cell wall-degrading enzymes (PCWDEs). Although pathogenicity in these bacteria is complex, virulence levels are proportional to the levels of plant cell wall-degrading exoenzymes (PCWDEs) secreted. Two low enzyme-producing transposon Tn5 mutants were isolated, and compared to their parent KD100, the mutants were less virulent on celery petioles and carrot disks. The inactivated gene responsible for the reduced virulence phenotype in both mutants was identified as wcaG. The gene, wcaG (previously denoted fcl) encodes NAD-dependent epimerase/dehydratase, a homologue of GDP-fucose synthetase of Escherichia coli. In Escherichia coli, GDP-fucose synthetase is involved in the biosynthesis of the exopolysaccharide, colanic acid (CA). The wcaG mutants of P. carotovorum formed an enhanced level of biofilm in comparison to their parent. In the hydrophobicity test the mutants showed more hydrophobicity than the parent in hexane and hexadecane as solvents. Complementation of the mutants with extrachromosomal copies of the wild type gene restored these functions to parental levels. These data indicate that NAD-dependent epimerase/dehydratase plays a vital rule in cell surface properties, exoenzyme production, and virulence in P. carotovorum.

Activities of plant cell wall-degrading enzymes by bacterial soft rot of orchid

2013 ◽  
Vol 47 (10) ◽  
pp. 1239-1250 ◽  
Author(s):  
Tri Joko ◽  
Ahmad Subandi ◽  
Nanda Kusumandari ◽  
Arif Wibowo ◽  
Achmadi Priyatmojo
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Soft Rot ◽  
Bacterial Soft Rot ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes

scholarly journals The Bacterial Soft Rot Pathogens, Pectobacterium carotovorum and P. atrosepticum, Respond to Different Classes of Virulence-Inducing Host Chemical Signals

Horticulturae ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 13
Author(s):  
Paul A. Agyemang ◽  
Md Niamul Kabir ◽  
Caleb M. Kersey ◽  
C. Korsi Dumenyo
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Soft Rot ◽  
Class Ii ◽  
Chemical Signals ◽  
Water Soluble ◽  
Negative Regulator ◽  
Class I ◽  
Cell Wall Degrading Enzymes

Soft rot bacteria of the Pectobacterium and Dickeya genera are Gram-negative phytopathogens that produce and secrete plant cell wall-degrading enzymes (PCWDE), the actions of which lead to rotting and decay of their hosts in the field and in storage. Host chemical signals are among the factors that induce the bacteria into extracellular enzyme production and virulence. A class of compounds (Class I) made up of intermediate products of cell wall (pectin) degradation induce exoenzyme synthesis through KdgR, a global negative regulator of exoenzyme production. While the KdgR− mutant of P. carotovorum is no longer inducible by Class I inducers, we demonstrated that exoenzyme production is induced in this strain in the presence of extracts from hosts including celery, potato, carrot, and tomato, suggesting that host plants contain another class of compounds (Class II inducers) different from the plant cell wall-degradative products that work through KdgR. The Class II inducers are thermostable, water-soluble, diffusible, and dialysable through 1 kDa molecular weight cut off pore size membranes, and could be a target for soft rot disease management strategies.

scholarly journals Arabidopsis thaliana Cells: A Model to Evaluate the Virulence of Pectobacterium carotovorum

2010 ◽  
Vol 23 (2) ◽  
pp. 139-143 ◽  
Author(s):  
Meriam Terta ◽  
Mohamed Kettani-Halabi ◽  
Khadija Ibenyassine ◽  
Daniel Tran ◽  
Patrice Meimoun ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Death ◽  
Plant Cell ◽  
Plant Pathogens ◽  
Plant Cell Wall ◽  
Pectate Lyase ◽  
Soft Rot ◽  
Pectobacterium Carotovorum ◽  
Cell Wall Degrading Enzymes ◽  
Suspension Cells

Pectobacterium carotovorum are economically important plant pathogens that cause plant soft rot. These enterobacteria display high diversity world-wide. Their pathogenesis depends on production and secretion of virulence factors such as plant cell wall–degrading enzymes, type III effectors, a necrosis-inducing protein, and a secreted virulence factor from Xanthomonas spp., which are tightly regulated by quorum sensing. Pectobacterium carotovorum also present pathogen-associated molecular patterns that could participate in their pathogenicity. In this study, by using suspension cells of Arabidopsis thaliana, we correlate plant cell death and pectate lyase activities during coinfection with different P. carotovorum strains. When comparing soft rot symptoms induced on potato slices with pectate lyase activities and plant cell death observed during coculture with Arabidopsis thaliana cells, the order of strain virulence was found to be the same. Therefore, Arabidopsis thaliana cells could be an alternative tool to evaluate rapidly and efficiently the virulence of different P. carotovorum strains.

scholarly journals A role for the Rcs phosphorelay in regulating expression of plant cell wall degrading enzymes in Pectobacterium carotovorum subsp. carotovorum

Microbiology ◽  
2010 ◽  
Vol 156 (5) ◽  
pp. 1323-1334 ◽  
Author(s):  
Liis Andresen ◽  
Erki Sala ◽  
Viia Kõiv ◽  
Andres Mäe
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Pathogenic Bacteria ◽  
Plant Cell Wall ◽  
Response Regulator ◽  
Pectobacterium Carotovorum ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes ◽  
Direct Binding

The Rcs phosphorelay is a signal transduction system that influences the virulence phenotype of several pathogenic bacteria. In the plant pathogen Pectobacterium carotovorum subsp. carotovorum (Pcc) the response regulator of the Rcs phosphorelay, RcsB, represses expression of plant cell wall degrading enzymes (PCWDE) and motility. The focus of this study was to identify genes directly regulated by the binding of RcsB that also regulate expression of PCWDE genes in Pcc. RcsB-binding sites within the regulatory regions of the flhDC operon and the rprA and rsmB genes were identified using DNase I protection assays, while in vivo studies using flhDC : : gusA, rsmB : : gusA and rprA : : gusA gene fusions revealed gene regulation. These experiments demonstrated that the operon flhDC, a flagellar master regulator, was repressed by RcsB, and transcription of rprA was activated by RcsB. Regulation of the rsmB promoter by RcsB is more complicated. Our results show that RcsB represses rsmB expression mainly through modulating flhDC transcription. Neverthless, direct binding of RcsB on the rsmB promoter region is possible in certain conditions. Using an rprA-negative mutant, it was further demonstrated that RprA RNA is not essential for regulating expression of PCWDE under the conditions tested, whereas overexpression of rprA increased protease expression in wild-type cells. Stationary-phase sigma factor, RpoS, is the only known target gene for RprA RNA in Escherichia coli; however, in Pcc the effect of RprA RNA was found to be rpoS-independent. Overall, our results show that the Rcs phosphorelay negatively affects expression of PCWDE by inhibiting expression of flhDC and rsmB.

scholarly journals Phloretin, an Apple Phytoalexin, Affects the Virulence and Fitness of Pectobacterium brasiliense by Interfering With Quorum-Sensing

2021 ◽  
Vol 12 ◽  
Author(s):  
Manoj Pun ◽  
Netaly Khazanov ◽  
Ortal Galsurker ◽  
Michal Weitman ◽  
Zohar Kerem ◽  
...  
Keyword(s):  
Cell Wall ◽  
Quorum Sensing ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Soft Rot ◽  
Homoserine Lactone ◽  
Cell Wall Degrading Enzymes ◽  
Docking Simulations ◽  
E Coli ◽  
Degrading Enzymes

The effects of phloretin a phytoalexin from apple, was tested on Pectobacterium brasiliense (Pb1692), an emerging soft-rot pathogen of potato. Exposure of Pb1692 to 0.2 mM phloretin a concentration that does not affect growth, or to 0.4 mM a 50% growth inhibiting concentration (50% MIC), reduced motility, biofilm formation, secretion of plant cell wall-degrading enzymes, production of acyl–homoserine lactone (AHL) signaling molecules and infection, phenotypes that are associated with bacterial population density-dependent system known as quorum sensing (QS). To analyze the effect of growth inhibition on QS, the activity of ciprofloxacin, an antibiotic that impairs cell division, was compared to that of phloretin at 50% MIC. Unlike phloretin, the antibiotic hardly affected the tested phenotypes. The use of DH5α, a QS-negative Escherichia coli strain, transformed with an AHL synthase (ExpI) from Pb1692, allowed to validate direct inhibition of AHL production by phloretin, as demonstrated by two biosensor strains, Chromobacterium violaceaum (CV026) and E. coli (pSB401). Expression analysis of virulence-related genes revealed downregulation of QS-regulated genes (expI, expR, luxS, rsmB), plant cell wall degrading enzymes genes (pel, peh and prt) and motility genes (motA, fim, fliA, flhC and flhD) following exposure to both phloretin concentrations. The results support the inhibition of ExpI activity by phloretin. Docking simulations were used to predict the molecular associations between phloretin and the active site of ExpI, to suggest a likely mode of action for the compound’s inhibition of virulence.

scholarly journals Synergistic Effect of Different Plant Cell Wall–Degrading Enzymes Is Important for Virulence of Fusarium graminearum

2017 ◽  
Vol 30 (11) ◽  
pp. 886-895 ◽  
Author(s):  
Maria Chiara Paccanaro ◽  
Luca Sella ◽  
Carla Castiglioni ◽  
Francesca Giacomello ◽  
Ana Lilia Martínez-Rocha ◽  
...  
Keyword(s):  
Cell Wall ◽  
Fusarium Graminearum ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Xylanase Activity ◽  
Cellulase Activity ◽  
Wild Type ◽  
Cell Wall Degrading Enzymes ◽  
Xylanase Production ◽  
Significant Difference

Endo-polygalacturonases (PGs) and xylanases have been shown to play an important role during pathogenesis of some fungal pathogens of dicot plants, while their role in monocot pathogens is less defined. Pg1 and xyr1 genes of the wheat pathogen Fusarium graminearum encode the main PG and the major regulator of xylanase production, respectively. Single- and double-disrupted mutants for these genes were obtained to assess their contribution to fungal infection. Compared with wild-type strain, the ∆pg mutant showed a nearly abolished PG activity, slight reduced virulence on soybean seedlings, but no significant difference in disease symptoms on wheat spikes; the ∆xyr mutant was strongly reduced in xylanase activity and moderately reduced in cellulase activity but was as virulent as wild type on both soybean and wheat plants. Consequently, the ΔpgΔxyr double mutant was impaired in xylanase, PG, and cellulase activities but, differently from single mutants, was significantly reduced in virulence on both plants. These findings demonstrate that the concurrent presence of PG, xylanase, and cellulase activities is necessary for full virulence. The observation that the uronides released from wheat cell wall after a F. graminearum PG treatment were largely increased by the fungal xylanases suggests that these enzymes act synergistically in deconstructing the plant cell wall.

Changes in Cell Surface Properties of Shiga Toxigenic Escherichia coli by Quercus infectoria G. Olivier

2009 ◽  
Vol 72 (8) ◽  
pp. 1699-1704 ◽  
Author(s):  
SUPAYANG PIYAWAN VORAVUTHIKUNCHAI ◽  
SAKOL SUWALAK
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Surface Properties ◽  
Cell Surface Hydrophobicity ◽  
Ethanolic Extract ◽  
Bacterial Cells ◽  
Electron Microscopic ◽  
Cell Surface Properties ◽  
E Coli ◽  
Quercus Infectoria

The effects of Quercus infectoria (family Fagaceae) nutgalls on cell surface properties of Shiga toxigenic Escherichia coli (STEC) were investigated with an assay of microbial adhesion to hydrocarbon. The surface of bacterial cells treated with Q. infectoria exhibited a higher level of cell surface hydrophobicity (CSH) toward toluene than did the surface of untreated cells. With 50% ethanolic extract, the CSH of the three strains of STEC O157:H7 treated with 4× MIC of the extract resulted in moderate or strong hydrophobicity, whereas at 2× MIC and MIC, the CSH of only one strain of E. coli O157:H7 was significantly affected. The 95% ethanolic extract had a significant effect on CSH of all three strains at both 4× MIC and 2× MIC but not at the MIC. The effect on bacterial CSH was less pronounced with the other STEC strains. At 4× MIC, the 50% ethanolic extract increased the CSH of all non-O157 STEC strains significantly. At 2× MIC and 4× MIC, the 95% ethanolic extract affected the CSH of E. coli O26:H11 significantly but did not affect E. coli O111:NM or E. coli O22. Electron microscopic examination revealed the loss of pili in the treated cells. The ability of Q. infectoria extract to modify hydrophobic domains enables this extract to partition the lipids of the bacterial cell membrane, rendering the membrane more permeable and allowing leakage of ions and other cell contents, which leads to cell death. Further studies are required to evaluate the effects of Q. infectoria extract in food systems or in vivo and provide support for the use of this extract as a food additive for control of these STEC pathogens.

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