scholarly journals Transcriptome Analysis of Trichothecene-Induced Gene Expression in Barley

2007 ◽  
Vol 20 (11) ◽  
pp. 1364-1375 ◽  
Author(s):  
Jayanand Boddu ◽  
Seungho Cho ◽  
Gary J. Muehlbauer
Keyword(s):  
Cell Death ◽  
Defense Response ◽  
Type Strain ◽  
Wild Type Strain ◽  
Loss Of Function ◽  
Wild Type ◽  
Genes Encoding ◽  
Basal Defense ◽  
Related Proteins ◽  
The Impact

Fusarium head blight, caused primarily by Fusarium graminearum, is a major disease problem on barley (Hordeum vulgare L.). Trichothecene mycotoxins produced by the fungus during infection increase the aggressiveness of the fungus and promote infection in wheat (Triticum aestivum L.). Loss-of-function mutations in the TRI5 gene in F. graminearum result in the inability to synthesize trichothecenes and in reduced virulence on wheat. We examined the impact of pathogen-derived trichothecenes on virulence and the transcriptional differences in barley spikes infected with a trichothecene-producing wild-type strain and a loss-of-function tri5 trichothecene nonproducing mutant. Disease severity, fungal biomass, and floret necrosis and bleaching were reduced in spikes inoculated with the tri5 mutant strain compared with the wild-type strain, indicating that the inability to synthesize trichothecenes results in reduced virulence in barley. We detected 63 transcripts that were induced during trichothecene accumulation, including genes encoding putative trichothecene detoxification and transport proteins, ubiquitination-related proteins, programmed cell death-related proteins, transcription factors, and cytochrome P450s. We also detected 414 gene transcripts that were designated as basal defense response genes largely independent of trichothecene accumulation. Our results show that barley exhibits a specific response to trichothecene accumulation that can be separated from the basal defense response. We propose that barley responds to trichothecene accumulation by inducing at least two general responses. One response is the induction of genes encoding trichothecene detoxification and transport activities that may reduce the impact of trichothecenes. The other response is to induce genes encoding proteins associated with ubiquitination and cell death which may promote successful establishment of the disease.

scholarly journals Expression and function of the cdgD gene, encoding a CHASE–PAS-DGC-EAL domain protein, in Azospirillum brasilense

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
José Francisco Cruz-Pérez ◽  
Roxana Lara-Oueilhe ◽  
Cynthia Marcos-Jiménez ◽  
Ricardo Cuatlayotl-Olarte ◽  
María Luisa Xiqui-Vázquez ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Soil Conditions ◽  
Wild Type ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Genes Encoding ◽  
In The Wild ◽  
Plant Growth Promoting

AbstractThe plant growth-promoting bacterium Azospirillum brasilense contains several genes encoding proteins involved in the biosynthesis and degradation of the second messenger cyclic-di-GMP, which may control key bacterial functions, such as biofilm formation and motility. Here, we analysed the function and expression of the cdgD gene, encoding a multidomain protein that includes GGDEF-EAL domains and CHASE and PAS domains. An insertional cdgD gene mutant was constructed, and analysis of biofilm and extracellular polymeric substance production, as well as the motility phenotype indicated that cdgD encoded a functional diguanylate protein. These results were correlated with a reduced overall cellular concentration of cyclic-di-GMP in the mutant over 48 h compared with that observed in the wild-type strain, which was recovered in the complemented strain. In addition, cdgD gene expression was measured in cells growing under planktonic or biofilm conditions, and differential expression was observed when KNO3 or NH4Cl was added to the minimal medium as a nitrogen source. The transcriptional fusion of the cdgD promoter with the gene encoding the autofluorescent mCherry protein indicated that the cdgD gene was expressed both under abiotic conditions and in association with wheat roots. Reduced colonization of wheat roots was observed for the mutant compared with the wild-type strain grown in the same soil conditions. The Azospirillum-plant association begins with the motility of the bacterium towards the plant rhizosphere followed by the adsorption and adherence of these bacteria to plant roots. Therefore, it is important to study the genes that contribute to this initial interaction of the bacterium with its host plant.

scholarly journals Impact of Inorganic Carbon Availability on Microcystin Production by Microcystis aeruginosa PCC 7806

2007 ◽  
Vol 73 (21) ◽  
pp. 6994-7002 ◽  
Author(s):  
Sabine J�hnichen ◽  
Tilo Ihle ◽  
Thomas Petzoldt ◽  
J�rgen Benndorf
Keyword(s):  
Microcystis Aeruginosa ◽  
Type Strain ◽  
Inorganic Carbon ◽  
Wild Type Strain ◽  
Light Cycle ◽  
Variable Fluorescence ◽  
Wild Type ◽  
Dark Light ◽  
Sodium Dependent ◽  
The Impact

ABSTRACT Batch culture experiments with the cyanobacterium Microcystis aeruginosa PCC 7806 were performed in order to test the hypothesis that microcystins (MCYSTs) are produced in response to a relative deficiency of intracellular inorganic carbon (Ci,i). In the first experiment, MCYST production was studied under increased Ci,i deficiency conditions, achieved by restricting sodium-dependent bicarbonate uptake through replacement of sodium bicarbonate in the medium with its potassium analog. The same experimental approach was used in a second experiment to compare the response of the wild-type strain M. aeruginosa PCC 7806 with its mcyB mutant, which lacks the ability to produce MCYSTs. In a third experiment, the impact of varying the Ci,i status on MCYST production was examined without suppressing the sodium-dependent bicarbonate transporter; instead, a detailed investigation of a dark-light cycle was performed. In all experiments, a relative Ci,i deficiency was indicated by an elevated variable fluorescence signal and led to enhanced phycocyanin cell quotas. Higher MCYST cell quotas (in the first and third experiments) and increased total (intracellular plus extracellular) MCYST production (in the first experiment) were detected with increased Ci,i deficiency. Furthermore, the MCYST-producing wild-type strain and its mcyB mutant showed basically the same response to restrained inorganic carbon uptake, with elevated variable fluorescence and phycocyanin cell quotas with increased Ci,i deficiency. The response of the wild type, however, was distinctly stronger and also included elevated chlorophyll a cell quotas. These differences indicate the limited ability of the mutant to adapt to low-Ci,i conditions. We concluded that MCYSTs may be involved in enhancing the efficiency of the adaptation of the photosynthetic apparatus to fluctuating inorganic carbon conditions in cyanobacterial cells.

scholarly journals Sialidase and Sialoglycoproteases Can Modulate Virulence in Porphyromonas gingivalis

2011 ◽  
Vol 79 (7) ◽  
pp. 2779-2791 ◽  
Author(s):  
Wilson Aruni ◽  
Elaine Vanterpool ◽  
Devon Osbourne ◽  
Francis Roy ◽  
Arun Muthiah ◽  
...  
Keyword(s):  
Porphyromonas Gingivalis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Content Type ◽  
Sialidase Activity ◽  
Catalytic Domains ◽  
Virulence Regulation ◽  
Isogenic Mutants ◽  
Related Proteins

ABSTRACTThePorphyromonas gingivalisrecombinant VimA can interact with the gingipains and several other proteins, including a sialidase. Sialylation can be involved in protein maturation; however, its role in virulence regulation inP. gingivalisis unknown. The three sialidase-related proteins inP. gingivalisshowed the characteristic sialidase Asp signature motif (SXDXGXTW) and other unique domains. To evaluate the roles of the associated genes, randomly chosenP. gingivalisisogenic mutants created by allelic exchange and designated FLL401 (PG0778::ermF), FLL402 (PG1724::ermF), and FLL403 (PG0352::ermF-ermAM) were characterized. Similar to the wild-type strain, FLL402 and FLL403 displayed a black-pigmented phenotype in contrast to FLL401, which was not black pigmented. Sialidase activity inP. gingivalisFLL401 was reduced by approximately 70% in comparison to those in FLL402 and FLL403, which were reduced by approximately 42% and 5%, respectively. Although there were no changes in the expression of the gingipain genes, their activities were reduced by 60 to 90% in all the isogenic mutants compared to that for the wild type. Immunoreactive bands representing the catalytic domains for RgpA, RgpB, and Kgp were present in FLL402 and FLL403 but were missing in FLL401. While adhesion was decreased, the capacity for invasion of epithelial cells by the isogenic mutants was increased by 11 to 16% over that of the wild-type strain. Isogenic mutants defective inPG0778andPG0352were more sensitive to hydrogen peroxide than the wild type. Taken together, these results suggest that theP. gingivalissialidase activity may be involved in regulating gingipain activity and other virulence factors and may be important in the pathogenesis of this organism.

scholarly journals Comparative analysis and mutation effects of fpp2–fpp1 tandem genes encoding proteolytic extracellular enzymes of Flavobacterium psychrophilum

Microbiology ◽  
2011 ◽  
Vol 157 (4) ◽  
pp. 1196-1204 ◽  
Author(s):  
David Pérez-Pascual ◽  
Esther Gómez ◽  
Beatriz Álvarez ◽  
Jessica Méndez ◽  
Pilar Reimundo ◽  
...  
Keyword(s):  
Gene Function ◽  
Type Strain ◽  
Wild Type Strain ◽  
Proteolytic Enzymes ◽  
Function Analysis ◽  
Phenotypic Characterization ◽  
Pcr Analysis ◽  
Wild Type ◽  
Flavobacterium Psychrophilum ◽  
Genes Encoding

Flavobacterium psychrophilum is a very significant fish pathogen that secretes two biochemically characterized extracellular proteolytic enzymes, Fpp1 and Fpp2. The genes encoding these enzymes are organized as an fpp2–fpp1 tandem in the genome of strain F. psychrophilum THC02/90. Analysis of the corresponding encoded proteins showed that they belong to two different protease families. For gene function analysis, new genetic tools were developed in F. psychrophilum by constructing stable isogenic fpp1 and fpp2 mutants via single-crossover homologous recombination. RT-PCR analysis of wild-type and mutant strains suggested that both genes are transcribed as a single mRNA from the promoter located upstream of the fpp2 gene. Phenotypic characterization of the fpp2 mutant showed lack of caseinolytic activity and higher colony spreading compared with the wild-type strain. Both characteristics were recovered in the complemented strain. One objective of this work was to assess the contribution to virulence of these proteolytic enzymes. LD50 experiments using the wild-type strain and mutants showed no significant differences in virulence in a rainbow trout challenge model, suggesting instead a possible nutritional role. The gene disruption procedure developed in this work, together with the knowledge of the complete genome sequence of F. psychrophilum, open new perspectives for the study of gene function in this bacterium.

scholarly journals Effects of Deletion of Genes Encoding Fe-Only Hydrogenase of Desulfovibrio vulgaris Hildenborough on Hydrogen and Lactate Metabolism

2002 ◽  
Vol 184 (3) ◽  
pp. 679-686 ◽  
Author(s):  
Brant K. J. Pohorelic ◽  
Johanna K. Voordouw ◽  
Elisabeth Lojou ◽  
Alain Dolla ◽  
Jens Harder ◽  
...  
Keyword(s):  
Sulfate Reduction ◽  
Electron Donor ◽  
Type Strain ◽  
Wild Type Strain ◽  
Physiological Role ◽  
Hydrogen Uptake ◽  
Desulfovibrio Vulgaris ◽  
Lactate Metabolism ◽  
Wild Type ◽  
Genes Encoding

ABSTRACT The physiological properties of a hyd mutant of Desulfovibrio vulgaris Hildenborough, lacking periplasmic Fe-only hydrogenase, have been compared with those of the wild-type strain. Fe-only hydrogenase is the main hydrogenase of D. vulgaris Hildenborough, which also has periplasmic NiFe- and NiFeSe-hydrogenases. The hyd mutant grew less well than the wild-type strain in media with sulfate as the electron acceptor and H2 as the sole electron donor, especially at a high sulfate concentration. Although the hyd mutation had little effect on growth with lactate as the electron donor for sulfate reduction when H2 was also present, growth in lactate- and sulfate-containing media lacking H2 was less efficient. The hyd mutant produced, transiently, significant amounts of H2 under these conditions, which were eventually all used for sulfate reduction. The results do not confirm the essential role proposed elsewhere for Fe-only hydrogenase as a hydrogen-producing enzyme in lactate metabolism (W. A. M. van den Berg, W. M. A. M. van Dongen, and C. Veeger, J. Bacteriol. 173:3688–3694, 1991). This role is more likely played by a membrane-bound, cytoplasmic Ech-hydrogenase homolog, which is indicated by the D. vulgaris genome sequence. The physiological role of periplasmic Fe-only hydrogenase is hydrogen uptake, both when hydrogen is and when lactate is the electron donor for sulfate reduction.

scholarly journals Insights into an alternative pathway for glycerol metabolism in a glycerol kinase deficientPseudomonas putidaKT2440

2019 ◽  
Author(s):  
Meg Walsh ◽  
William Casey ◽  
Shane T. Kenny ◽  
Tanja Narancic ◽  
Lars M. Blank ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Alternative Pathway ◽  
Glycerol Kinase ◽  
Glycerol Metabolism ◽  
Wild Type ◽  
Short Chain Length ◽  
Genes Encoding ◽  
In The Wild

AbstractPseudomonas putidaKT2440 is known to metabolise glycerol via glycerol-3-phosphate using glycerol kinase an enzyme previously described as critical for glycerol metabolism (1). However, when glycerol kinase was knocked out inP. putidaKT2440 it retained the ability to use glycerol as the sole carbon source, albeit with a much-extended lag period and 2 fold lower final biomass compared to the wild type strain. A metabolomic study identified glycerate as a major and the most abundant intermediate in glycerol metabolism in this mutated strain with levels 21-fold higher than wild type. Erythrose-4-phosphate was detected in the mutant strain, but not in the wild type strain. Glyceraldehyde and glycraldehyde-3-phosphate were detected at similar levels in the mutant strain and the wild type. Transcriptomic studies identified 191 genes that were more than 2-fold upregulated in the mutant compared to the wild type and 175 that were down regulated. The genes involved in short chain length fatty acid metabolism were highly upregulated in the mutant strain. The genes encoding 3-hydroxybutyrate dehydrogenase were 5.8-fold upregulated and thus the gene was cloned, expressed and purified to reveal it can act on glyceraldehyde but not glycerol as a substrate.

scholarly journals Redox-Dependent Gene Regulation inRhodobacter sphaeroides 2.4.1T: Effects on Dimethyl Sulfoxide Reductase (dor) Gene Expression

1998 ◽  
Vol 180 (21) ◽  
pp. 5612-5618 ◽  
Author(s):  
Nigel J. Mouncey ◽  
Samuel Kaplan
Keyword(s):  
Gene Expression ◽  
Dimethyl Sulfoxide ◽  
Type Strain ◽  
Wild Type Strain ◽  
Strictly Aerobic ◽  
Wild Type ◽  
Dmso Reductase ◽  
Regulatory Cascade ◽  
Expression Of Genes ◽  
Genes Encoding

ABSTRACT The ability of Rhodobacter sphaeroides2.4.1T to respire anaerobically with the alternative electron acceptor dimethyl sulfoxide (DMSO) or trimethylamineN-oxide (TMAO) is manifested by the molybdoenzyme DMSO reductase, which is encoded by genes of the dor locus. Previously, we have demonstrated that dor expression is regulated in response to lowered oxygen tensions and the presence of DMSO or TMAO in the growth medium. Several regulatory proteins have been identified as key players in this regulatory cascade: FnrL, DorS-DorR, and DorX-DorY. To further examine the role of redox potentiation in the regulation of dor expression, we measured DMSO reductase synthesis and β-galactosidase activity fromdor::lacZ fusions in strains containing mutations in the redox-active proteins CcoP and RdxB, which have previously been implicated in the generation of a redox signal affecting photosynthesis gene expression. Unlike the wild-type strain, both mutants were able to synthesize DMSO reductase under strictly aerobic conditions, even in the absence of DMSO. When cells were grown photoheterotrophically, dorC::lacZexpression was stimulated by increasing light intensity in the CcoP mutant, whereas it is normally repressed in the wild-type strain under such conditions. Furthermore, the expression of genes encoding the DorS sensor kinase and DorR response regulator proteins was also affected by the ccoP mutation. By using CcoP-DorR and CcoP-DorY double mutants, it was shown that the DorR protein is strictly required for altered dor expression in CcoP mutants. These results further demonstrate a role for redox-generated responses in the expression of genes encoding DMSO reductase in R. sphaeroides and identify the DorS-DorR proteins as a redox-dependent regulatory system controlling dorexpression.

scholarly journals Nitrite and Nitrous Oxide Reductase Regulation by Nitrogen Oxides in Rhodobacter sphaeroides f. sp.denitrificans IL106

1999 ◽  
Vol 181 (19) ◽  
pp. 6028-6032 ◽  
Author(s):  
Monique Sabaty ◽  
Carole Schwintner ◽  
Sandrine Cahors ◽  
Pierre Richaud ◽  
Andre Verméglio
Keyword(s):  
Nitrous Oxide ◽  
Nitrate Reductase ◽  
Rhodobacter Sphaeroides ◽  
Type Strain ◽  
Biochemical Analysis ◽  
Wild Type Strain ◽  
Nitrous Oxide Reductase ◽  
Wild Type ◽  
Genes Encoding ◽  
Membrane Bound

ABSTRACT We have cloned the nap locus encoding the periplasmic nitrate reductase in Rhodobacter sphaeroides f. sp.denitrificans IL106. A mutant with this enzyme deleted is unable to grow under denitrifying conditions. Biochemical analysis of this mutant shows that in contrast to the wild-type strain, the level of synthesis of the nitrite and N2O reductases is not increased by the addition of nitrate. Growth under denitrifying conditions and induction of N oxide reductase synthesis are both restored by the presence of a plasmid containing the genes encoding the nitrate reductase. This demonstrates that R. sphaeroides f. sp. denitrificans IL106 does not possess an efficient membrane-bound nitrate reductase and that nitrate is not the direct inducer for the nitrite and N2O reductases in this species. In contrast, we show that nitrite induces the synthesis of the nitrate reductase.

scholarly journals Global Analysis of Cellular Factors and Responses Involved in Pseudomonas aeruginosa Resistance to Arsenite

2005 ◽  
Vol 187 (14) ◽  
pp. 4853-4864 ◽  
Author(s):  
Kislay Parvatiyar ◽  
Eyad M. Alsabbagh ◽  
Urs A. Ochsner ◽  
Michelle A. Stegemeyer ◽  
Alan G. Smulian ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Pseudomonas Aeruginosa ◽  
Glutathione Reductase ◽  
Type Strain ◽  
Wild Type Strain ◽  
Storage Proteins ◽  
Global Analysis ◽  
Wild Type ◽  
Isogenic Mutants ◽  
The Impact

ABSTRACT The impact of arsenite [As(III)] on several levels of cellular metabolism and gene regulation was examined in Pseudomonas aeruginosa. P. aeruginosa isogenic mutants devoid of antioxidant enzymes or defective in various metabolic pathways, DNA repair systems, metal storage proteins, global regulators, or quorum sensing circuitry were examined for their sensitivity to As(III). Mutants lacking the As(III) translocator (ArsB), superoxide dismutase (SOD), catabolite repression control protein (Crc), or glutathione reductase (Gor) were more sensitive to As(III) than wild-type bacteria. The MICs of As(III) under aerobic conditions were 0.2, 0.3, 0.8, and 1.9 mM for arsB, sodA sodB, crc, and gor mutants, respectively, and were 1.5- to 13-fold less than the MIC for the wild-type strain. A two-dimensional gel/matrix-assisted laser desorption ionization-time of flight analysis of As(III)-treated wild-type bacteria showed significantly (>40-fold) increased levels of a heat shock protein (IbpA) and a putative allo-threonine aldolase (GlyI). Smaller increases (up to 3.1-fold) in expression were observed for acetyl-coenzyme A acetyltransferase (AtoB), a probable aldehyde dehydrogenase (KauB), ribosomal protein L25 (RplY), and the probable DNA-binding stress protein (PA0962). In contrast, decreased levels of a heme oxygenase (HemO/PigA) were found upon As(III) treatment. Isogenic mutants were successfully constructed for six of the eight genes encoding the aforementioned proteins. When treated with sublethal concentrations of As(III), each mutant revealed a marginal to significant lag period prior to resumption of apparent normal growth compared to that observed in the wild-type strain. Our results suggest that As(III) exposure results in an oxidative stress-like response in P. aeruginosa, although activities of classic oxidative stress enzymes are not increased. Instead, relief from As(III)-based oxidative stress is accomplished from the collective activities of ArsB, glutathione reductase, and the global regulator Crc. SOD appears to be involved, but its function may be in the protection of superoxide-sensitive sulfhydryl groups.

scholarly journals A general framework for modelling the impact of co-infections on pathogen evolution

2019 ◽  
Vol 16 (155) ◽  
pp. 20190165 ◽  
Author(s):  
Mary Bushman ◽  
Rustom Antia
Keyword(s):  
Mutant Strain ◽  
Type Strain ◽  
General Framework ◽  
Wild Type Strain ◽  
Theoretical Models ◽  
Epidemiological Model ◽  
Wild Type ◽  
Pathogen Evolution ◽  
Evolutionary Emergence ◽  
The Impact

Theoretical models suggest that mixed-strain infections, or co-infections, are an important driver of pathogen evolution. However, the within-host dynamics of co-infections vary enormously, which complicates efforts to develop a general understanding of how co-infections affect evolution. Here, we develop a general framework which condenses the within-host dynamics of co-infections into a few key outcomes, the most important of which is the overall R 0 of the co-infection. Similar to how fitness is determined by two different alleles in a heterozygote, the R 0 of a co-infection is a product of the R 0 values of the co-infecting strains, shaped by the interaction of those strains at the within-host level. Extending the analogy, we propose that the overall R 0 reflects the dominance of the co-infecting strains, and that the ability of a mutant strain to invade a population is a function of its dominance in co-infections. To illustrate the utility of these concepts, we use a within-host model to show how dominance arises from the within-host dynamics of a co-infection, and then use an epidemiological model to demonstrate that dominance is a robust predictor of the ability of a mutant strain to save a maladapted wild-type strain from extinction (evolutionary emergence).

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