scholarly journals The Leucine-Responsive Regulatory Protein Lrp Participates in Virulence Regulation Downstream of Small RNA ArcZ inErwinia amylovora

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Jeffrey K. Schachterle ◽  
George W. Sundin
Keyword(s):  
Small Rna ◽  
Transcriptional Activation ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Regulatory Protein ◽  
Regulatory Control ◽  
Transcriptional Level ◽  
Content Type ◽  
Virulence Regulation ◽  
Blight Disease

ABSTRACTErwinia amylovoracauses the devastating fire blight disease of apple and pear trees. During systemic infection of host trees, pathogen cells must rapidly respond to changes in their environment as they move through different host tissues that present distinct challenges and sources of nutrition. Growing evidence indicates that small RNAs (sRNAs) play an important role in disease progression as posttranscriptional regulators. The sRNA ArcZ positively regulates the motility phenotype and transcription of flagellar genes inE. amylovoraEa1189 yet is a direct repressor of translation of the flagellar master regulator, FlhD. We utilized transposon mutagenesis to conduct a forward genetic screen and identified suppressor mutations that increase motility in the Ea1189ΔarcZmutant background. This enabled us to determine that the mechanism of transcriptional activation of theflhDCmRNA by ArcZ is mediated by the leucine-responsive regulatory protein, Lrp. We show that Lrp contributes to expression of virulence and several virulence-associated traits, including production of the exopolysaccharide amylovoran, levansucrase activity, and biofilm formation. We further show that Lrp is regulated posttranscriptionally by ArcZ through destabilization oflrpmRNA. Thus, ArcZ regulation of FlhDC directly and indirectly through Lrp forms an incoherent feed-forward loop that regulates levansucrase activity and motility as outputs. This work identifies Lrp as a novel participant in virulence regulation inE. amylovoraand places it in the context of a virulence-associated regulatory network.IMPORTANCEFire blight disease continues to plague the commercial production of apples and pears despite more than a century of research into disease epidemiology and disease control. The causative agent of fire blight,Erwinia amylovoracoordinates turning on or off specific virulence-associated traits at the appropriate time during disease development. The development of novel control strategies requires an in-depth understanding ofE. amylovoraregulatory mechanisms, including regulatory control of virulence-associated traits. This study investigates how the small RNA ArcZ regulates motility at the transcriptional level and identifies the transcription factor Lrp as a novel participant in the regulation of several virulence-associated traits. We report that ArcZ and Lrp together affect key virulence-associated traits through integration of transcriptional and posttranscriptional mechanisms. Further understanding of the topology of virulence regulatory networks can uncover weak points that can subsequently be exploited to controlE. amylovora.

scholarly journals Whole-Genome Sequence of Pseudomonas fluorescens EK007-RG4, a Promising Biocontrol Agent against a Broad Range of Bacteria, Including the Fire Blight Bacterium Erwinia amylovora

2017 ◽  
Vol 5 (13) ◽  
Author(s):  
Roghayeh Habibi ◽  
Saeed Tarighi ◽  
Javad Behravan ◽  
Parissa Taheri ◽  
Annelise Helene Kjøller ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Genome Sequence ◽  
Pathogenic Bacteria ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Whole Genome Sequence ◽  
Whole Genome ◽  
Content Type ◽  
Pear Tree ◽  
Blight Disease

ABSTRACT Here, we report the first draft whole-genome sequence of Pseudomonas fluorescens strain EK007-RG4, which was isolated from the phylloplane of a pear tree. P. fluorescens EK007-RG4 displays strong antagonism against Erwinia amylovora, the causal agent for fire blight disease, in addition to several other pathogenic and non-pathogenic bacteria.

scholarly journals Virulence Genetics of an Erwinia amylovora Putative Polysaccharide Transporter Family Member

2020 ◽  
Vol 202 (22) ◽  
Author(s):  
Sara M. Klee ◽  
Judith P. Sinn ◽  
Elena Christian ◽  
Aleah C. Holmes ◽  
Kaixi Zhao ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Control Measures ◽  
Detectable Effect ◽  
Wild Type ◽  
Content Type ◽  
Transporter Family ◽  
Blight Disease ◽  
Suppressor Screen

ABSTRACT The Gram-negative enterobacterium Erwinia amylovora causes fire blight disease in apple and pear trees. Lipopolysaccharides and the exopolysaccharide amylovoran are essential E. amylovora virulence factors. We found that mutations in rfbX disrupted amylovoran production and virulence in apple fruits and tree shoots and that the deletion of yibD suppressed the rfbX mutant phenotype. The level of expression of yibD was about 10-fold higher in the ΔrfbX mutant than the wild type. A forward genetic suppressor screen in the ΔrfbX mutant uncovered multiple mutations in yibD and supported the conclusion that the virulence defect of rfbX mutants is due to reduced amylovoran production. The yibD and rfbX genes are expressed as a two-gene operon, yibD rfbX. The rfbX gene encodes a previously uncharacterized putative polysaccharide subunit transporter, while yibD encodes a predicted glycosyltransferase. Mutation of rfbX did not have a detectable effect on lipopolysaccharide patterns; however, the overexpression of yibD in both the wild-type and ΔyibD ΔrfbX genetic backgrounds disrupted both amylovoran and lipopolysaccharide production. Additionally, the overexpression of yibD in the ΔyibD ΔrfbX mutant inhibited bacterial growth in amylovoran-inducing medium. This growth inhibition phenotype was used in a forward genetic suppressor screen and reverse-genetics tests to identify several genes involved in lipopolysaccharide production, which, when mutated, restored the ability of the ΔyibD ΔrfbX mutant overexpressing yibD to grow in amylovoran-inducing medium. Remarkably, all the lipopolysaccharide gene mutants tested were defective in lipopolysaccharide and amylovoran production. These results reveal a genetic connection between amylovoran and lipopolysaccharide production in E. amylovora. IMPORTANCE This study discovered previously unknown genetic connections between exopolysaccharide and lipopolysaccharide production in the fire blight pathogen Erwinia amylovora. This represents a step forward in our understanding of the biology underlying the production of these two macromolecules. Fire blight is an economically important disease that impacts the production of apples and pears worldwide. Few fire blight control measures are available, and growers rely heavily on antibiotic applications at bloom time. Both exopolysaccharide and lipopolysaccharide are E. amylovora virulence factors. Our results indicate that the overexpression of the yibD gene in E. amylovora disrupts both lipopolysaccharide production and exopolysaccharide production. This effect could potentially be used as the basis for the development of an antivirulence treatment for the prevention of fire blight disease.

scholarly journals Evaluation of Susceptibility of Different Pear Hybrid Populations to Fire Blight (Erwinia amylovora)

2011 ◽  
Vol 39 (1) ◽  
pp. 226 ◽  
Author(s):  
Yasemin EVRENOSOĞLU ◽  
Adalet MISIRLI ◽  
Hikmet SAYGILI ◽  
Emre BİLEN ◽  
Özlem BOZTEPE ◽  
...  
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Open Pollination ◽  
Resistance Level ◽  
Class A ◽  
Class B ◽  
Artificial Inoculations ◽  
Serious Disease ◽  
Blight Disease ◽  
Santa Maria

Fire blight disease caused by pathogenic bacterium Erwinia amylovora, is the serious disease of pear, and there is not a certain chemical management against this disease except antibiotic-type compounds such as streptomycin. It is very important to improve new fire blight resistant cultivars in case of integrated disease management. With this purpose, different crosses have been made between Pyrus communis varieties that have good fruit characteristics and resistant cultigens. Besides, self and open pollination treatments have been carried out in maternal plants. The disease resistance level of the hybrids obtained from these combinations was determined by artificial inoculations by Erwinia amylovora in greenhouse conditions. A total of 3284 hybrids were inoculated, and 2631 of them survived and were distributed to different susceptibility classes. 19.88% of the inoculated hybrids was killed by Erwinia amylovora. Total distribution of the hybrids to susceptibility classes was as 6.18% in class “A- slightly susceptible”, 3.11% in class “B- less susceptible”, 8.89% in class “C- mid-susceptible”, 20.28% in class “D- susceptible”, and 61.54% in class “E- very susceptible”. Majority of class “A- slightly susceptible” hybrids were obtained from ‘Magness’ x ‘Ankara’ combination. ‘Kieffer’ x ‘Santa Maria’, ‘Kieffer’ open pollination, ‘Magness’ x ‘Akça’, ‘Magness’ x ‘Kieffer’, ‘Magness’ x ‘Santa Maria’, ‘Mustafa Bey’ x ‘Moonglow’ treatments displayed good results with respect to “A- slightly susceptible” character. It is very important to evaluate these hybrid pear populations through different fruit and tree characteristics in the future.

scholarly journals Transcriptional Regulation of the Copper Transporter Mfc1 in Meiotic Cells

2013 ◽  
Vol 12 (4) ◽  
pp. 575-590 ◽  
Author(s):  
Jude Beaudoin ◽  
Raphaël Ioannoni ◽  
Stéphane Mailloux ◽  
Samuel Plante ◽  
Simon Labbé
Keyword(s):  
Transcriptional Activation ◽  
Regulatory Element ◽  
Specific Protein ◽  
Copper Transport ◽  
Site Directed Mutagenesis ◽  
Regulatory Sequence ◽  
Transcriptional Level ◽  
Binding Studies ◽  
Copper Transporter ◽  
Content Type

ABSTRACT Mfc1 is a meiosis-specific protein that mediates copper transport during the meiotic program in Schizosaccharomyces pombe . Although the mfc1 + gene is induced at the transcriptional level in response to copper deprivation, the molecular determinants that are required for its copper starvation-dependent induction are unknown. Promoter deletion and site-directed mutagenesis have allowed identification of a new cis -regulatory element in the promoter region of the mfc1 + gene. This cis -acting regulatory sequence containing the sequence TCGGCG is responsible for transcriptional activation of mfc1 + under low-copper conditions. The TCGGCG sequence contains a CGG triplet known to serve as a binding site for members of the Zn (2) Cys (6) binuclear cluster transcriptional regulator family. In agreement with this fact, one member of this group of regulators, denoted Mca1, was found to be required for maximum induction of mfc1 + gene expression. Analysis of Mca1 cellular distribution during meiosis revealed that it colocalizes with both chromosomes and sister chromatids during early, middle, and late phases of the meiotic program. Cells lacking Mca1 exhibited a meiotic arrest at metaphase I under low-copper conditions. Binding studies revealed that the N-terminal 150-residue segment of Mca1 expressed as a fusion protein in Escherichia coli specifically interacts with the TCGGCG sequence of the mfc1 + promoter. Taken together, these results identify the cis -regulatory TCGGCG sequence and the transcription factor Mca1 as critical components for activation of the meiotic copper transport mfc1 + gene in response to copper starvation.

scholarly journals RbsR Activates Capsule but Represses therbsUDKOperon in Staphylococcus aureus

2015 ◽  
Vol 197 (23) ◽  
pp. 3666-3675 ◽  
Author(s):  
Mei G. Lei ◽  
Chia Y. Lee
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factor ◽  
Transcriptional Activation ◽  
Promoter Region ◽  
Mobility Shift ◽  
Content Type ◽  
Virulence Regulation ◽  
Important Virulence Factor ◽  
Dna Fragment ◽  
Mobility Shift Assay

ABSTRACTStaphylococcus aureuscapsule is an important virulence factor that is regulated by a large number of regulators. Capsule genes are expressed from a major promoter upstream of thecapoperon. A 10-bp inverted repeat (IR) located 13 bp upstream of the −35 region of the promoter was previously shown to affect capsule gene transcription. However, little is known about transcriptional activation of thecappromoter. To search for potential proteins which directly interact with thecappromoter region (Pcap), we directly analyzed the proteins interacting with the PcapDNA fragment from shifted gel bands identified by electrophoretic mobility shift assay. One of these regulators, RbsR, was further characterized and found to positively regulatecapgene expression by specifically binding to thecappromoter region. Footprinting analyses showed that RbsR protected a DNA region encompassing the 10-bp IR. Our results further showed thatrbsRwas directly controlled by SigB and that RbsR was a repressor of therbsUDKoperon, involved in ribose uptake and phosphorylation. The repression ofrbsUDKby RbsR could be derepressed byd-ribose. However,d-ribose did not affect RbsR activation of capsule.IMPORTANCEStaphylococcus aureusis an important human pathogen which produces a large number of virulence factors. We have been using capsule as a model virulence factor to study virulence regulation. Although many capsule regulators have been identified, the mechanism of regulation of most of these regulators is unknown. We show here that RbsR activates capsule by direct promoter binding and that SigB is required for the expression ofrbsR. These results define a new pathway wherein SigB activates capsule through RbsR. Our results further demonstrate that RbsR inhibits therbsoperon involved in ribose utilization, thereby providing an example of coregulation of metabolism and virulence inS. aureus. Thus, this study further advances our understanding of staphylococcal virulence regulation.

New potential bacterial antagonists for the biocontrol of fire blight disease (Erwinia amylovora) in Morocco

2018 ◽  
Vol 117 ◽  
pp. 7-15 ◽  
Author(s):  
Smail Ait Bahadou ◽  
Abderrahmane Ouijja ◽  
Abdelkarim Karfach ◽  
Abdessalem Tahiri ◽  
Rachid Lahlali
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Bacterial Antagonists ◽  
Blight Disease

scholarly journals Chromosomally Encodedhok-sokToxin-Antitoxin System in the Fire Blight PathogenErwinia amylovora: Identification and Functional Characterization

2019 ◽  
Vol 85 (15) ◽  
Author(s):  
Jingyu Peng ◽  
Lindsay R. Triplett ◽  
Jeffrey K. Schachterle ◽  
George W. Sundin
Keyword(s):  
Noncoding Rna ◽  
Pathogenic Bacteria ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Functional Characterization ◽  
Pathogenic Bacterium ◽  
Type I ◽  
Plant Pathogenic Bacterium ◽  
Content Type ◽  
Protein Toxin

ABSTRACTToxin-antitoxin (TA) systems are genetic elements composed of a protein toxin and a counteracting antitoxin that is either a noncoding RNA or protein. In type I TA systems, the antitoxin is a noncoding small RNA (sRNA) that base pairs with the cognate toxin mRNA interfering with its translation. Although type I TA systems have been extensively studied inEscherichia coliand a few human or animal bacterial pathogens, they have not been characterized in plant-pathogenic bacteria. In this study, we characterized a chromosomal locus in the plant pathogenErwinia amylovoraEa1189 that is homologous to thehok-soktype I TA system previously identified in theEnterobacteriaceae-restricted plasmid R1. Phylogenetic analysis indicated that the chromosomal location of thehok-soklocus is, thus far, unique toE. amylovora. We demonstrated that ectopic overexpression ofhokis highly toxic toE. amylovoraand that the sRNAsokreversed the toxicity ofhokthroughmok, a reading frame presumably translationally coupled withhok. We also identified the region that is essential for maintenance of the main toxicity of Hok. Through ahok-sokdeletion mutant (Ea1189Δhok-sok), we determined the contribution of thehok-soklocus to cellular growth, micromorphology, and catalase activity. Combined, our findings indicate that thehok-sokTA system, besides being potentially self-toxic, provides fitness advantages toE. amylovora.IMPORTANCEBacterial toxin-antitoxin systems have received great attention because of their potential as targets for antimicrobial development and as tools for biotechnology.Erwinia amylovora, the causal agent of fire blight disease on pome fruit trees, is a major plant-pathogenic bacterium. In this study, we identified and functionally characterized a unique chromosomally encodedhok-soktoxin-antitoxin system inE. amylovorathat resembles the plasmid-encoded copies of this system in otherEnterobacteriaceae. This study of a type I toxin-antitoxin system in a plant-pathogenic bacterium provides the basis to further understand the involvement of toxin-antitoxin systems during infection by a plant-pathogenic bacterium. The new linkage between thehok-soktoxin-antitoxin system and the catalase-mediated oxidative stress response leads to additional considerations of targeting this system for antimicrobial development.

scholarly journals Effects of Exposure Time and Biological State on Acquisition and Accumulation of Erwinia amylovora by Drosophila melanogaster

2019 ◽  
Vol 85 (15) ◽  
Author(s):  
Matthew Boucher ◽  
Rowan Collins ◽  
Kerik Cox ◽  
Greg Loeb
Keyword(s):  
Drosophila Melanogaster ◽  
Exposure Time ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Current Knowledge ◽  
Selective Medium ◽  
Nutritional State ◽  
Biological Factors ◽  
Content Type ◽  
Disease Cycle

ABSTRACT Fire blight, caused by the bacterium Erwinia amylovora, is a disease devastating the production of rosaceous crops, primarily apple and pear, with worldwide distribution. Fire blight begins in the spring when primary inoculum is produced as ooze, which consists of plant sap, E. amylovora, and exopolysaccharides. Ooze is believed to be transferred to healthy tissues by wind, rain, and insects. However, the mechanisms by which insects locate and transmit ooze are largely undocumented. The goals of this study were to investigate the biological factors affecting acquisition of E. amylovora from ooze by a model dipteran, Drosophila melanogaster, and to determine whether flies are able to mechanically transfer this bacterium after acquisition. We found that the percentage of positive flies increased as exposure time increased, but nutritional state, mating status, and sex did not significantly alter the number of positive individuals. Bacterial abundance was highly variable at all exposure times, suggesting that other biological factors play a role in acquisition. Nutritional state had a significant effect on E. amylovora abundance, and food-deprived flies had higher E. amylovora counts than satiated flies. We also demonstrated that D. melanogaster transmits E. amylovora to a selective medium surface and hypothesize that the same is possible for plant surfaces, where bacteria can persist until an opportunity to colonize the host arises. Collectively, these data suggest a more significant role for flies than previously thought in transmission of fire blight and contribute to a shift in our understanding of the E. amylovora disease cycle. IMPORTANCE A recent hypothesis proposed that dissemination of Erwinia amylovora from ooze by flies to native rosaceous trees was likely key to the life cycle of the bacterium during its evolution. Our study validates an important component of this hypothesis by showing that flies are capable of acquiring and transmitting this bacterium from ooze under various biotic conditions. Understanding how dipterans interact with ooze advances our current knowledge of its epidemiological function and provides strong evidence for an underappreciated role of flies in the disease cycle. These findings may be especially important as they pertain to shoot blight, because this stage of the disease is poorly understood and may involve a significant amount of insect activity. Broadly, this study underscores a need to consider the depth, breadth, and origin of interactions between flies and E. amylovora to better understand its epidemiology.

scholarly journals Host-Derived Metabolites Modulate Transcription ofSalmonellaGenes Involved in L-Lactate Utilization during Gut Colonization

2019 ◽  
Vol 87 (4) ◽  
Author(s):  
Caroline C. Gillis ◽  
Maria G. Winter ◽  
Rachael B. Chanin ◽  
Wenhan Zhu ◽  
Luisella Spiga ◽  
...  
Keyword(s):  
Cell Metabolism ◽  
Regulatory Protein ◽  
Transcriptional Level ◽  
Lactate Oxidation ◽  
Terminal Electron Acceptor ◽  
Content Type ◽  
Gut Colonization ◽  
Serovar Typhimurium ◽  
Lactate Utilization

ABSTRACTDuringSalmonella entericaserovar Typhimurium infection, host inflammation alters the metabolic environment of the gut lumen to favor the outgrowth of the pathogen at the expense of the microbiota. Inflammation-driven changes in host cell metabolism lead to the release ofl-lactate and molecular oxygen from the tissue into the gut lumen.Salmonellautilizes lactate as an electron donor in conjunction with oxygen as the terminal electron acceptor to support gut colonization. Here, we investigated transcriptional regulation of the respiratoryl-lactate dehydrogenase LldDin vitroand in mouse models ofSalmonellainfection. The two-component system ArcAB repressed transcription ofl-lactate utilization genes under anaerobic conditionsin vitro. The ArcAB-mediated repression oflldDtranscription was relieved under microaerobic conditions. Transcription oflldDwas induced byl-lactate but notd-lactate. A mutant lacking the regulatory protein LldR failed to inducelldDtranscription in response tol-lactate. Furthermore, thelldRmutant exhibited reduced transcription ofl-lactate utilization genes and impaired fitness in murine models of infection. These data provide evidence that the host-derived metabolites oxygen andl-lactate serve as cues forSalmonellato regulate lactate oxidation metabolism on a transcriptional level.

scholarly journals Involvement of PatE, a Prophage-Encoded AraC-Like Regulator, in the Transcriptional Activation of Acid Resistance Pathways of Enterohemorrhagic Escherichia coli Strain EDL933

2012 ◽  
Vol 78 (15) ◽  
pp. 5083-5092 ◽  
Author(s):  
Jennifer K. Bender ◽  
Judyta Praszkier ◽  
Matthew J. Wakefield ◽  
Kathryn Holt ◽  
Marija Tauschek ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Transcriptional Activation ◽  
Regulatory Protein ◽  
Acid Resistance ◽  
Enterohemorrhagic Escherichia Coli ◽  
Transcriptional Analysis ◽  
Mobility Shift ◽  
Content Type ◽  
Infectious Dose ◽  
Genes Encoding

ABSTRACTEnterohemorrhagicEscherichia coli(EHEC) O157:H7 is a lethal human intestinal pathogen that causes hemorrhagic colitis and the hemolytic-uremic syndrome. EHEC is transmitted by the fecal-oral route and has a lower infectious dose than most other enteric bacterial pathogens in that fewer than 100 CFU are able to cause disease. This low infectious dose has been attributed to the ability of EHEC to survive in the acidic environment of the human stomach.In silicoanalysis of the genome of EHEC O157:H7 strain EDL933 revealed a gene,patE, for a putative AraC-like regulatory protein within the prophage island, CP-933H. Transcriptional analysis inE. colishowed that the expression ofpatEis induced during stationary phase. Data from microarray assays demonstrated that PatE activates the transcription of genes encoding proteins of acid resistance pathways. In addition, PatE downregulated the expression of a number of genes encoding heat shock proteins and the type III secretion pathway of EDL933. Transcriptional analysis and electrophoretic mobility shift assays suggested that PatE also activates the transcription of the gene for the acid stress chaperonehdeAby binding to its promoter region. Finally, assays of acid tolerance showed that increasing the expression of PatE in EHEC greatly enhanced the ability of the bacteria to survive in different acidic environments. Together, these findings indicate that EHEC strain EDL933 carries a prophage-encoded regulatory system that contributes to acid resistance.

Sign in / Sign up

Export Citation Format

Share Document