Extracellular amylase is required for full virulence and regulated by the global post-transcriptional regulator RsmA in Xanthomonas campestris pathovar campestris

2020 ◽  
Author(s):  
Jiliang Tang ◽  
Yan Lin ◽  
Yong-Yan Liao ◽  
Ru-Xia Huang ◽  
Ai-Zhou Li ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Extracellular Enzymes ◽  
Amylase Activity ◽  
Transcriptional Regulator ◽  
Transcriptional Level ◽  
In Trans ◽  
Extracellular Amylase ◽  
Rot Disease ◽  
Post Transcriptional Regulation ◽  
Cruciferous Plants

As with many phytopathogenic bacteria, the virulence of Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot disease in cruciferous plants, relies on secretion of a suite of extracellular enzymes that includes cellulase (endoglucanase), pectinase, protease and amylase. Although the role in virulence of a number of these enzymes has been assessed, the contribution of amylase to Xcc virulence has yet to be established. In this work, we investigated both the role of extracellular amylase in Xcc virulence and the control of its expression. Deletion of XC3487 (here renamed amyAXcc), a putative amylase-encoding gene from the genome of Xcc strain 8004, resulted in a complete loss of extracellular amylase activity and significant reduction in virulence. The extracellular amylase activity and virulence of the amyAXcc mutant could be restored to the wild-type level by expressing amyAXcc in trans. These results demonstrated that amyAXcc is responsible for the extracellular amylase activity of Xcc, and indicated that extracellular amylase plays an important role in Xcc virulence. We further found that the expression of amyAXcc is strongly induced by starch and requires activation by the global post-transcriptional regulator RsmA. RsmA binds specifically to the 5’-untranslated region (5’UTR) of amyAXcc transcripts, suggesting that RsmA regulates amyAXcc directly at the post-transcriptional level. Unexpectedly, in addition to post-transcriptional regulation, the use of a transcriptional reporter demonstrated that RsmA also regulates amyAXcc expression at the transcriptional level, possibly by an indirect mechanism.

scholarly journals Complex transcriptional regulation of the Saccharomyces cerevisiae CYB2 gene encoding cytochrome b2: CYP1(HAP1) activator binds to the CYB2 upstream activation site UAS1-B2.

1991 ◽  
Vol 11 (7) ◽  
pp. 3762-3772 ◽  
Author(s):  
T Lodi ◽  
B Guiard
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Regulatory Region ◽  
Transcriptional Regulator ◽  
Direct Analysis ◽  
Transcriptional Level ◽  
Glucose Fermentation ◽  
Gene Encoding ◽  
Dnase I Footprinting ◽  
Mrna Transcripts ◽  
Binding Sequence

Expression of the Saccharomyces cerevisiae gene encoding cytochrome b2 (EC 1.2.2.3), CYB2, was investigated by direct analysis of mRNA transcripts and by measurement of the expression of lacZ fused to the CYB2 control regions. These studies indicated that regulation of the CYB2 gene is subject to several metabolic controls at the transcriptional level: inhibition due to glucose fermentation, induction by lactate, and inhibition in anaerobiosis or in absence of heme biosynthesis. Furthermore, we have shown that the CYB2 promoter contains one cis negative regulatory region and two heme-dependent positive regions, one of which is controlled by the transcriptional regulator CYP1 (HAP1) which is involved in the modulation of the expression of several oxygen-regulated genes. The CYP1 (HAP1)-binding sequence was located by gel retardation and DNase I footprinting experiments and compared with the binding sequences previously characterized in detail (UAS1CYC1, UAS'CYP3 (CYC7), and UASCTT1).

scholarly journals Iron-Responsive Repression of Urease Expression in Helicobacter hepaticus Is Mediated by the Transcriptional Regulator Fur

2006 ◽  
Vol 75 (2) ◽  
pp. 745-752 ◽  
Author(s):  
Clara Belzer ◽  
Bart A. M. van Schendel ◽  
Ernst J. Kuipers ◽  
Johannes G. Kusters ◽  
Arnoud H. M. van Vliet
Keyword(s):  
Urease Activity ◽  
Transcriptional Regulator ◽  
Mammalian Host ◽  
Transcriptional Level ◽  
Helicobacter Hepaticus ◽  
Mucosal Surfaces ◽  
Insertional Inactivation ◽  
Fur Protein ◽  
Colonization Factors ◽  
Gene Recombinant

ABSTRACT Persistent colonization of mucosal surfaces by bacteria in the mammalian host requires concerted expression of colonization factors, depending on the environmental conditions. Helicobacter hepaticus is a urease-positive pathogen that colonizes the intestinal and hepatobiliary tracts of rodents. Here it is reported that urease expression of H. hepaticus is iron repressed by the transcriptional regulator Fur. Iron restriction of growth medium resulted in a doubling of urease activity in wild-type H. hepaticus strain ATCC 51449 and was accompanied by increased levels of urease subunit proteins and ureA mRNA. Insertional inactivation of the fur gene abolished iron-responsive repression of urease activity, whereas inactivation of the perR gene did not affect iron-responsive regulation of urease activity. The iron-responsive promoter element was identified directly upstream of the H. hepaticus ureA gene. Recombinant H. hepaticus Fur protein bound to this ureA promoter region in a metal-dependent matter, and binding resulted in the protection of a 41-bp, Fur box-containing operator sequence located at positions −35 to −75 upstream of the transcription start site. In conclusion, H. hepaticus Fur controls urease expression at the transcriptional level in response to iron availability. This represents a novel type of urease regulation in ureolytic bacteria and extends the already diverse regulatory repertoire of the Fur protein.

scholarly journals The Distinctive Regulation of Cyanobacterial Glutamine Synthetase

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 52 ◽  
Author(s):  
Paul Bolay ◽  
M. Muro-Pastor ◽  
Francisco Florencio ◽  
Stephan Klähn
Keyword(s):  
Glutamine Synthetase ◽  
Gene Expression Regulation ◽  
Feedback Inhibition ◽  
Current Knowledge ◽  
Transcriptional Level ◽  
Distinctive Features ◽  
Small Proteins ◽  
Regulatory Systems ◽  
Covalent Modifications ◽  
Post Transcriptional Regulation

Glutamine synthetase (GS) features prominently in bacterial nitrogen assimilation as it catalyzes the entry of bioavailable nitrogen in form of ammonium into cellular metabolism. The classic example, the comprehensively characterized GS of enterobacteria, is subject to exquisite regulation at multiple levels, among them gene expression regulation to control GS abundance, as well as feedback inhibition and covalent modifications to control enzyme activity. Intriguingly, the GS of the ecologically important clade of cyanobacteria features fundamentally different regulatory systems to those of most prokaryotes. These include the interaction with small proteins, the so-called inactivating factors (IFs) that inhibit GS linearly with their abundance. In addition to this protein interaction-based regulation of GS activity, cyanobacteria use alternative elements to control the synthesis of GS and IFs at the transcriptional level. Moreover, cyanobacteria evolved unique RNA-based regulatory mechanisms such as glutamine riboswitches to tightly tune IF abundance. In this review, we aim to outline the current knowledge on the distinctive features of the cyanobacterial GS encompassing the overall control of its activity, sensing the nitrogen status, transcriptional and post-transcriptional regulation, as well as strain-specific differences.

scholarly journals Characterization of Xanthomonas campestris pv. campestris in Algeria

2021 ◽  
Vol 60 (1) ◽  
pp. 51-62
Author(s):  
Samia LAALA ◽  
Sophie CESBRON ◽  
Mohamed KERKOUD ◽  
Franco VALENTINI ◽  
Zouaoui BOUZNAD ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Housekeeping Genes ◽  
First Record ◽  
Black Rot ◽  
Physiological And Biochemical Characteristics ◽  
Main Production ◽  
Production Areas ◽  
Cruciferous Plants ◽  
Xanthomonas Campestris Pv Campestris

Xanthomonas campestris pv. campestris (Xcc) causes the black rot of cruciferous plants. This seed-borne bacterium is considered as the most destructive disease to cruciferous crops. Although sources of contamination are various, seeds are the main source of transmission. Typical symptoms of black rot were first observed in 2011 on cabbage and cauliflower fields in the main production areas of Algeria. Leaf samples displaying typical symptoms were collected during 2011 to 2014, and 170 strains were isolated from 45 commercial fields. Xcc isolates were very homogeneous in morphological, physiological and biochemical characteristics similar to reference strains, and gave positive pathogenicity and molecular test results (multiplex PCR with specific primers). This is the first record of Xcc in Algeria. Genetic diversity within the isolates was assessed in comparison with strains isolated elsewhere. A multilocus sequence analysis based on two housekeeping genes (gyrB and rpoD) was carried out on 77 strains representative isolates. The isolates grouped into 20 haplotypes defined with 68 polymorphic sites. The phylogenetic tree obtained showed that Xcc is in two groups, and all Algerian strains clustered in group 1 in three subgroups. No relationships were detected between haplotypes and the origins of the seed lots, the varieties of host cabbage, the years of isolation and agroclimatic regions.

scholarly journals Evaluating the Antibacterial Activity and Mode of Action of Thymol-Loaded Chitosan Nanoparticles Against Plant Bacterial Pathogen Xanthomonas campestris pv. campestris

2022 ◽  
Vol 12 ◽  
Author(s):  
Sarangapani Sreelatha ◽  
Nadimuthu Kumar ◽  
Tan Si Yin ◽  
Sarojam Rajani
Keyword(s):  
Electron Microscopy ◽  
Antibacterial Activity ◽  
Xanthomonas Campestris ◽  
Membrane Damage ◽  
Chitosan Nanoparticles ◽  
Bacterial Pathogen ◽  
Electron Microscopy Analysis ◽  
Rot Disease ◽  
The Impact

The bacterium Xanthomonas campestris pv. campestris (Xcc) causes black rot disease in cruciferous crops, resulting in severe yield loss worldwide. The excessive use of chemical pesticides in agriculture to control diseases has raised significant concern about the impact on the environment and human health. Nanoparticles have recently gained significant attention in agriculture owing to their promising application in plant disease control, increasing soil fertility and nutrient availability. In the current study, we synthesized thymol-loaded chitosan nanoparticles (TCNPs) and assessed their antibacterial activity against Xcc. The synthesis of TCNPs was confirmed by using ultraviolet–visible spectroscopy. Fourier-transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy analysis revealed the functional groups, size, and shape of TCNPs, with sizes ranging from 54 to 250 nm, respectively. The antibacterial activity of TCNPs against Xcc was investigated in vitro by liquid broth, cell viability, and live dead staining assay, and all of them demonstrated the antibacterial activity of TCNPs. Furthermore, TCNPs were found to directly inhibit the growth of Xcc by suppressing the growth of biofilm formation and the production of exopolysaccharides and xanthomonadin. The ultrastructure studies revealed membrane damage in TCNP-treated Xcc cells, causing a release of intracellular contents. Headspace/gas chromatography (GC)–mass spectrometry (MS) analysis showed changes in the volatile profile of Xcc cells treated with TCNPs. Increased amounts of carbonyl components (mainly ketones) and production of new volatile metabolites were observed in Xcc cells incubated with TCNPs. Overall, this study reveals TCNPs as a promising antibacterial candidate against Xcc.

scholarly journals Glucosinolate Profile and Glucosinolate Biosynthesis and Breakdown Gene Expression Manifested by Black Rot Disease Infection in Cabbage

Plants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1121
Author(s):  
Mehede Hassan Rubel ◽  
Md. Abuyusuf ◽  
Ujjal Kumar Nath ◽  
Arif Hasan Khan Robin ◽  
Hee Jeong Jung ◽  
...  
Keyword(s):  
Gene Expression ◽  
Xanthomonas Campestris ◽  
Defense Mechanism ◽  
Expression Patterns ◽  
Functional Characterization ◽  
Brassica Species ◽  
Black Rot ◽  
Clear Understanding ◽  
Knock Out ◽  
Rot Disease

Cabbage (Brassica oleracea var. capitata) is an economically important crop in the family Brassicaceae. Black rot disease is a top ranked cabbage disease, which is caused by Xanthomonas campestris pv. campestris (Xcc) and may reduce 50% crop loss. Therefore, we need a clear understanding of black rot disease resistance for sustainable disease management. The secondary metabolites, like Glucosinolate (GSL) presents in Brassica species, which plays a potential role in the defense mechanism against pathogens. However, there is little known about GSL-regulated resistance mechanisms and GSL biosynthesis and the breakdown related gene expression after black rot disease infection in cabbage. In this study, relative expression of 43 biosynthetic and breakdown related GSLs were estimated in the black rot resistant and susceptible cabbage lines after Xcc inoculation. Ten different types of GSL from both aliphatic and indolic groups were identified in the contrasting cabbage lines by HPLC analysis, which included six aliphatic and four indolic compounds. In the resistant line, nine genes (MYB122-Bol026204, MYB34-Bol017062, AOP2-Bo9g006240, ST5c-Bol030757, CYP81F1-Bol017376, CYP81F2-Bol012237, CYP81F4-Bol032712, CYP81F4-Bol032714 and PEN2-Bol030092) showed consistent expression patterns. Pearson’s correlation coefficient showed positive and significant association between aliphatic GSL compounds and expression values of ST5c-Bol030757 and AOP2-Bo9g006240 genes as well as between indolic GSL compounds and the expression of MYB34-Bol017062, MYB122-Bol026204, CYP81F2-Bol012237, CYP81F4-Bol032712 and CYP81F4-Bol032714 genes. This study helps in understanding the role of GSL biosynthesis and breakdown related genes for resistance against black rot pathogen in cabbage, which could be further confirmed through functional characterization either by overexpression or knock-out mutation.

Exploration of the Use of the “Bialaphos Genes” for Improving Bioherbicide Efficacy

1996 ◽  
Vol 10 (3) ◽  
pp. 625-636 ◽  
Author(s):  
R. Charudattan ◽  
V. J. Prange ◽  
J. T. Devalerio
Keyword(s):  
Host Range ◽  
Xanthomonas Campestris ◽  
Plant Pathogens ◽  
Strain Improvement ◽  
Tetracycline Resistance ◽  
Plasmid Vector ◽  
E Coli ◽  
Normal Expression ◽  
Natural Hosts ◽  
Rot Disease

We are studying the possibility of altering the virulence and host range of a phytopathogen by transferring and expressing certain genes from the soil-dwelling saprophyte,Streptomyces hygroscopicus, in a plant pathogen model,Xanthomonas campestrispv.campestris(XCC). The genes, referred to herein as the “bialaphos genes,” encode the production of bialaphos, a potent glutamine-synthetase-inhibiting herbicide. This cluster of genes was originally isolated from several biosynthetically blocked mutants ofS. hygroscopicusand constructed into a plasmid vector, pBG9. We have transferred a fragment of the gene cluster into pLAFR3, a plasmid that functions in bothEscherichia coliand XCC and contains a tetracycline resistance marker. The resulting plasmid, named pIL-1, was used to transformE. coliand was incorporated into XCC by conjugation. The transfer of the fragment was confirmed by Southern analysis. The genes were maintained in XCC for about 47 generations in the absence of selection for tetracycline, and no changes in cultural phenotypes were seen in the transformed XCC (XCC/pIL-1). The XCC/pIL-1 cells were pathogenic to their natural hosts cabbage and broccoli, but induced an altered hypersensitive response in the nonhosts bean, pepper, sunflower, and tobacco. The pathogenic host-reaction, induced by the parent XCC, XCC/pLAFR3, and XCC/pIL-1, was a typical black rot disease in inoculated leaves of the two hosts. The nonhost reaction on the nonhost leaves was necrotic hypersensitivity, induced by XCC and XCC/pLAFR3, or the inhibition of hypersensitivity accompanied by only chlorosis at sites inoculated with XCC/pIL-1. We hypothesize that the altered hypersensitivity phenotype may be due to the transformed XCC becoming more compatible with the nonhosts, a step toward acquiring nonhost-virulence, or due to disruption of the normal expression of the hypersensitivity and pathogenicity genes in the transformed XCC. More work is needed to confirm that the introduced genes are being expressed in XCC. With further understanding, this approach may provide a useful model to study host range, virulence, and strain improvement of plant pathogens for biological control of weeds.

scholarly journals hpaR, a Putative marR Family Transcriptional Regulator, Is Positively Controlled by HrpG and HrpX and Involved in the Pathogenesis, Hypersensitive Response, and Extracellular Protease Production of Xanthomonas campestris Pathovar campestris

2006 ◽  
Vol 189 (5) ◽  
pp. 2055-2062 ◽  
Author(s):  
Ke Wei ◽  
Dong-Jie Tang ◽  
Yong-Qiang He ◽  
Jia-Xun Feng ◽  
Bo-Le Jiang ◽  
...  
Keyword(s):  
Hypersensitive Response ◽  
Xanthomonas Campestris ◽  
Transcriptional Regulator ◽  
Transcriptional Regulators ◽  
Extracellular Protease ◽  
Protease Production ◽  
Phytopathogenic Bacterium ◽  
Cellular Processes ◽  
Glucuronidase Activity ◽  
Nonhost Plant

ABSTRACT The MarR family of transcriptional regulators of bacteria are involved in the regulation of many cellular processes, including pathogenesis. In this work, we have demonstrated genetically that hpaR (hpa, hrp associated), which encodes a putative MarR family regulator, is involved in the hypersensitive response (HR), pathogenicity, and extracellular protease production of the phytopathogenic bacterium Xanthomonas campestris pathovar campestris. A mutation in hpaR resulted in complete loss of virulence in the host plant cabbage, a delayed and weakened HR in the nonhost plant pepper ECW-10R, and an increase in extracellular protease production. Detection of the β-glucuronidase activity of a plasmid-driven hpaR promoter-gusA reporter revealed that the expression of hpaR is positively controlled by HrpG and HrpX and is suppressed in rich medium while being strongly induced in minimal and hrp-inducing media and inside the host. These findings indicate that hpaR belongs to the hrpG and hrpX regulon and that HrpX regulates the extracellular protease production via hpaR in X. campestris pv. campestris.

scholarly journals Ribosome-Profiling Reveals Restricted Post Transcriptional Expression of Antiviral Cytokines and Transcription Factors during SARS-CoV-2 Infection

2021 ◽  
Vol 22 (7) ◽  
pp. 3392
Author(s):  
Marina R. Alexander ◽  
Aaron M. Brice ◽  
Petrus Jansen van Vuren ◽  
Christina L. Rootes ◽  
Leon Tribolet ◽  
...  
Keyword(s):  
Transcriptional Regulation ◽  
Transcription Factors ◽  
Host Response ◽  
High Viral Load ◽  
Ribosome Profiling ◽  
Epithelial Cell Line ◽  
Transcriptional Level ◽  
Human Lung Epithelial Cell ◽  
Post Transcriptional Regulation ◽  
The Impact

The global COVID-19 pandemic caused by SARS-CoV-2 has resulted in over 2.2 million deaths. Disease outcomes range from asymptomatic to severe with, so far, minimal genotypic change to the virus so understanding the host response is paramount. Transcriptomics has become incredibly important in understanding host-pathogen interactions; however, post-transcriptional regulation plays an important role in infection and immunity through translation and mRNA stability, allowing tight control over potent host responses by both the host and the invading virus. Here, we apply ribosome profiling to assess post-transcriptional regulation of host genes during SARS-CoV-2 infection of a human lung epithelial cell line (Calu-3). We have identified numerous transcription factors (JUN, ZBTB20, ATF3, HIVEP2 and EGR1) as well as select antiviral cytokine genes, namely IFNB1, IFNL1,2 and 3, IL-6 and CCL5, that are restricted at the post-transcriptional level by SARS-CoV-2 infection and discuss the impact this would have on the host response to infection. This early phase restriction of antiviral transcripts in the lungs may allow high viral load and consequent immune dysregulation typically seen in SARS-CoV-2 infection.

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