scholarly journals SlyA, a MarR Family Transcriptional Regulator, Is Essential for Virulence in Dickeya dadantii 3937

2009 ◽  
Vol 191 (17) ◽  
pp. 5409-5418 ◽  
Author(s):  
M. Manjurul Haque ◽  
M. Shahinur Kabir ◽  
Luqman Qurata Aini ◽  
Hisae Hirata ◽  
Shinji Tsuyumu
Keyword(s):  
Pathogenic Bacteria ◽  
Pectate Lyase ◽  
Transcriptional Regulator ◽  
Polymyxin B ◽  
In Planta ◽  
Cationic Antimicrobial Peptide ◽  
Dickeya Dadantii ◽  
Increased Sensitivity ◽  
Gene Deletion Mutant ◽  
And Oxidative Stress

ABSTRACT SlyA, a MarR family transcriptional regulator, controls an assortment of biological functions in several animal-pathogenic bacteria. In order to elucidate the functions of SlyA in the phytopathogen Dickeya dadantii (formerly Erwinia chrysanthemi) 3937, a slyA gene deletion mutant (denoted ΔslyA) was constructed. The mutant exhibited increased sensitivity to sodium hypochlorite, the cationic antimicrobial peptide polymyxin B, and oxidative stress. The mutant showed reduced production of pectate lyase and exopolysaccharide and an inability to form a pellicle. The mutant lacking a functional slyA gene showed a significantly reduced ability to cause maceration of potato tubers. Accordingly, the mutant exhibited significantly reduced bacterial growth and failed to hyperinduce pectate lyase production in planta. Introduction of a plasmid containing slyA into the ΔslyA mutant caused all of these phenotypes to recover to wild-type levels. These results suggest that SlyA plays an important role in virulence to plants by positively regulating the expression of multiple pathogenicity-related traits of D. dadantii 3937.

scholarly journals The pbgPE operon in Photorhabdus luminescens Is Required for Pathogenicity and Symbiosis

2005 ◽  
Vol 187 (1) ◽  
pp. 77-84 ◽  
Author(s):  
H. P. J. Bennett ◽  
D. J. Clarke
Keyword(s):  
Galleria Mellonella ◽  
Polymyxin B ◽  
Infective Juvenile ◽  
Acidic Ph ◽  
Photorhabdus Luminescens ◽  
Insect Larvae ◽  
Cationic Antimicrobial Peptide ◽  
O Antigen ◽  
Mutualistic Relationship ◽  
Increased Sensitivity

ABSTRACT Photorhabdus is a genus of gram-negative Enterobacteriaceae that is pathogenic to insect larvae while also maintaining a mutualistic relationship with nematodes from the family Heterorhabditis, where the bacteria occupy the gut of the infective juvenile (IJ) stage of the nematode. In this study we describe the identification and characterization of a mutation in the pbgE1 gene of Photorhabdus luminescens TT01, predicted to be the fifth gene in the pbgPE operon. We show that this mutant, BMM305, is strongly attenuated in virulence against larvae of the greater wax moth, Galleria mellonella, and we report that BMM305 is more sensitive to the cationic antimicrobial peptide, polymyxin B, and growth in mildly acidic pH than the parental strain of P. luminescens. Moreover, we also show that the lipopolysaccharide (LPS) present on the surface of BMM305 does not appear to contain any O antigen. Complementation studies reveal that the increased sensitivity to polymyxin B and growth in mildly acidic pH can be rescued by the in trans expression of pbgE1, while the defects in O-antigen assembly and pathogenicity require the in trans expression of pbgE1 and the downstream genes pbgE2 and pbgE3. Finally, we show that BMM305 is defective in symbiosis as this mutant is unable to colonize the gut of the IJ stage of the nematode. Therefore, we conclude that the pbgPE operon is required for both pathogenicity and symbiosis in P. luminescens.

scholarly journals PhoP-PhoQ Two-Component System Required for Colonization Leading to Virulence of Dickeya dadantii 3937 in planta

1970 ◽  
Vol 25 (1) ◽  
pp. 36-40 ◽  
Author(s):  
M Manjurul Haque ◽  
Kamrun Nahar ◽  
M Abdur Rahim ◽  
Isidore Gomes ◽  
Shinji Tsuyumu
Keyword(s):  
Chinese Cabbage ◽  
Bacterial Population ◽  
Pectate Lyase ◽  
In Planta ◽  
Two Component System ◽  
Bacterial Populations ◽  
Dickeya Dadantii ◽  
Component System ◽  
Two Component ◽  
Infected Area

Previously, we have reported that the PhoP-PhoQ two-component system (TCS) is essential for synthesis of pectate lyase, resistance to antimicrobial peptide and accumulation of acetyl-coenzyme A in Dickeya dadantii 3937. In this study, marker-exchange mutagenesis of phoP and phoQ of D. dadantii 3937 resulted in loss of virulence in Chinese cabbage and a severe reduction of bacterial population in infected area and its surrounding healthy tissue was also seen. Inoculation of bacteria grown and re-suspended in medium containing low concentration of Mg2+ resulted in reduced virulence and significantly reduced bacterial population in wild type while these mutants showed higher virulence and higher bacterial populations at high Mg2+ condition. Since Mg2+ concentration was detected to be very low (14.6 ± 4.23/100 g) in the apoplastic fluids of Chinese cabbage thus, the PhoP-PhoQ two-component system of D. dadantii 3937 is compromised virulence, at least in part, due to colonization of bacteria in planta responding to Mg2+. Keywords: Virulence; Bacterial population; Magnesium, Dickeya dadantiiDOI: http://dx.doi.org/10.3329/bjm.v25i1.4853 Bangladesh J Microbiol, Volume 25, Number 1, June 2008, pp 36-40

scholarly journals Commensal Effect of Pectate Lyases Secreted fromDickeya dadantiion Proliferation ofEscherichia coliO157:H7 EDL933 on Lettuce Leaves

2010 ◽  
Vol 77 (1) ◽  
pp. 156-162 ◽  
Author(s):  
Akihiro Yamazaki ◽  
Jin Li ◽  
William C. Hutchins ◽  
Lixia Wang ◽  
Jincai Ma ◽  
...  
Keyword(s):  
Pectate Lyase ◽  
Type Ii Secretion ◽  
Broad Host Range ◽  
Deficient Mutant ◽  
In Planta ◽  
Enzyme Activity Assay ◽  
Dickeya Dadantii ◽  
Pectate Lyases ◽  
Σ Factor ◽  
Tissue Maceration

ABSTRACTThe outbreaks caused by enterohemorrhagicEscherichia coliO157:H7 on leafy greens have raised serious and immediate food safety concerns. It has been suggested that several phytopathogens aid in the persistence and proliferation of the human enteropathogens in the phyllosphere. In this work, we examined the influence of virulence mechanisms ofDickeya dadantii3937, a broad-host-range phytopathogen, on the proliferation of the human pathogenE. coliO157:H7 EDL933 (EDL933) on postharvest lettuce by coinoculation of EDL933 withD. dadantii3937 derivatives that have mutations in virulence-related genes. A type II secretion system (T2SS)-deficient mutant ofD. dadantii3937, A1919 (ΔoutC), lost the capability to promote the multiplication of EDL933, whereas Ech159 (ΔrpoS), a stress-responsive σ factor RpoS-deficient mutant, increased EDL933 proliferation on lettuce leaves. A spectrophotometric enzyme activity assay revealed that A1919 (ΔoutC) was completely deficient in the secretion of pectate lyases (Pels), which play a major role in plant tissue maceration. In contrast to A1919 (ΔoutC), Ech159 (ΔrpoS) showed more than 2-fold-greater Pel activity than the wild-typeD. dadantii3937. Increased expression ofpelD(encodes an endo-pectate lyase) was observed in Ech159 (ΔrpoS)in planta. These results suggest that the pectinolytic activity ofD. dadantii3937 is the dominant determinant of enhanced EDL933 proliferation on the lettuce leaves. In addition, RpoS, the general stress response σ factor involved in cell survival in suboptimal conditions, plays a role in EDL933 proliferation by controlling the production of pectate lyases inD. dadantii3937.

scholarly journals Prediction and Activity of a Cationic α-Helix Antimicrobial Peptide ZM-804 from Maize

2021 ◽  
Vol 22 (5) ◽  
pp. 2643
Author(s):  
Mohamed F. Hassan ◽  
Abdelrahman M. Qutb ◽  
Wubei Dong
Keyword(s):  
Cdna Library ◽  
Pseudomonas Syringae ◽  
Inbred Line ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Pathogenic Bacteria ◽  
Antimicrobial Activities ◽  
Confocal Laser ◽  
In Planta ◽  
Minimal Inhibitory Concentrations

Antimicrobial peptides (AMPs) are small molecules consisting of less than fifty residues of amino acids. Plant AMPs establish the first barrier of defense in the innate immune system in response to invading pathogens. The purpose of this study was to isolate new AMPs from the Zea mays L. inbred line B73 and investigate their antimicrobial activities and mechanisms against certain essential plant pathogenic bacteria. In silico, the Collection of Anti-Microbial Peptides (CAMPR3), a computational AMP prediction server, was used to screen a cDNA library for AMPs. A ZM-804 peptide, isolated from the Z. mays L. inbred line B73 cDNA library, was predicted as a new cationic AMP with high prediction values. ZM-804 was tested against eleven pathogens of Gram-negative and Gram-positive bacteria and exhibited high antimicrobial activities as determined by the minimal inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs). A confocal laser scanning microscope observation showed that the ZM-804 AMP targets bacterial cell membranes. SEM and TEM images revealed the disruption and damage of the cell membrane morphology of Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato (Pst) DC3000 caused by ZM-804. In planta, ZM-804 demonstrated antimicrobial activity and prevented the infection of tomato plants by Pst DC3000. Moreover, four virulent phytopathogenic bacteria were prevented from inducing hypersensitive response (HR) in tobacco leaves in response to low ZM-804 concentrations. ZM-804 exhibits low hemolytic activity against mouse red blood cells (RBCs) and is relatively safe for mammalian cells. In conclusion, the ZM-804 peptide has a strong antibacterial activity and provides an alternative tool for plant disease control. Additionally, the ZM-804 peptide is considered a promising candidate for human and animal drug development.

scholarly journals In Silico Analyses of Rice Thionin Genes and the Antimicrobial Activity of OsTHION15 Against Phytopathogens

2019 ◽  
Vol 109 (1) ◽  
pp. 27-35
Author(s):  
Krissana Boonpa ◽  
Suparuk Tantong ◽  
Kamonwan Weerawanich ◽  
Pawinee Panpetch ◽  
Onanong Pringsulaka ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Stress Responses ◽  
In Silico ◽  
Pathogenic Bacteria ◽  
Hyphal Growth ◽  
In Planta ◽  
Recombinant Peptide ◽  
Plant Disease Control ◽  
Helminthosporium Oryzae ◽  
In Silico Analyses

Thionins are a family of antimicrobial peptides. We performed in silico expression analyses of the 44 rice (Oryza sativa) thionins (OsTHIONs). Modulated expression levels of OsTHIONs under different treatments suggest their involvement in many processes, including biotic, abiotic, and nutritional stress responses, and in hormone signaling. OsTHION15 (LOC_Os06g32600) was selected for further characterization based on several in silico analyses. OsTHION15 in O. sativa subsp. indica ‘KDML 105’ was expressed in all of the tissues and organs examined, including germinating seed, leaves, and roots of seedlings and mature plants, and inflorescences. To investigate the antimicrobial activity of OsTHION15, we produced a recombinant peptide in Escherichia coli Rosetta-gami (DE3). The recombinant OsTHION15 exhibited inhibitory activities toward rice-pathogenic bacteria such as Xanthomonas oryzae pv. oryzae and Pectobacterium carotovorum pv. atroseptica, with minimum inhibitory concentrations of 112.6 and 14.1 µg ml−1, respectively. A significant hyphal growth inhibition was also observed toward Fusarium oxysporum f. sp. cubense and Helminthosporium oryzae. In addition, we demonstrated the in planta antibacterial activity of this peptide in Nicotiana benthamiana against X. campestris pv. glycines. These activities suggest the possible application of OsTHION15 in plant disease control.

scholarly journals New Aspects of RpoE in Uropathogenic Proteus mirabilis

2014 ◽  
Vol 83 (3) ◽  
pp. 966-977 ◽  
Author(s):  
Ming-Che Liu ◽  
Kuan-Ting Kuo ◽  
Hsiung-Fei Chien ◽  
Yi-Lin Tsai ◽  
Shwu-Jen Liaw
Keyword(s):  
Urinary Tract ◽  
Virulence Factors ◽  
Stress Responses ◽  
Proteus Mirabilis ◽  
Immune Cell ◽  
Polymyxin B ◽  
Urothelial Cells ◽  
Cationic Antimicrobial Peptide ◽  
Content Type ◽  
Tract Infections

Proteus mirabilisis a common human pathogen causing recurrent or persistent urinary tract infections (UTIs). The underlying mechanisms forP. mirabilisto establish UTIs are not fully elucidated. In this study, we showed that loss of the sigma factor E (RpoE), mediating extracytoplasmic stress responses, decreased fimbria expression, survival in macrophages, cell invasion, and colonization in mice but increased the interleukin-8 (IL-8) expression of urothelial cells and swarming motility. This is the first study to demonstrate that RpoE modulated expression of MR/P fimbriae by regulatingmrpI, a gene encoding a recombinase controlling the orientation of MR/P fimbria promoter. By real-time reverse transcription-PCR, we found that the IL-8 mRNA amount of urothelial cells was induced significantly by lipopolysaccharides extracted fromrpoEmutant but not from the wild type. These RpoE-associated virulence factors should be coordinately expressed to enhance the fitness ofP. mirabilisin the host, including the avoidance of immune attacks. Accordingly,rpoEmutant-infected mice displayed more immune cell infiltration in bladders and kidneys during early stages of infection, and therpoEmutant had a dramatically impaired ability of colonization. Moreover, it is noteworthy that urea (the major component in urine) and polymyxin B (a cationic antimicrobial peptide) can induce expression ofrpoEby the reporter assay, suggesting that RpoE might be activated in the urinary tract. Altogether, our results indicate that RpoE is important in sensing environmental cues of the urinary tract and subsequently triggering the expression of virulence factors, which are associated with the fitness ofP. mirabilis, to build up a UTI.

scholarly journals Modeling the bioconversion of polysaccharides in a continuous reactor: A case study of the production of oligogalacturonates by Dickeya dadantii

2018 ◽  
Vol 294 (5) ◽  
pp. 1753-1762 ◽  
Author(s):  
Jacques-Alexandre Sepulchre ◽  
Sylvie Reverchon ◽  
Jean-Luc Gouzé ◽  
William Nasser
Keyword(s):  
A Priori ◽  
Pectate Lyase ◽  
Degradation Process ◽  
Continuous Reactor ◽  
Practical Implementation ◽  
Dickeya Dadantii ◽  
Pectate Lyases ◽  
Upper Limit ◽  
Promising Avenue

In the quest for a sustainable economy of the Earth's resources and for renewable sources of energy, a promising avenue is to exploit the vast quantity of polysaccharide molecules contained in green wastes. To that end, the decomposition of pectin appears to be an interesting target because this polymeric carbohydrate is abundant in many fruit pulps and soft vegetables. To quantitatively study this degradation process, here we designed a bioreactor that is continuously fed with de-esterified pectin (PGA). Thanks to the pectate lyases produced by bacteria cultivated in the vessel, the PGA is depolymerized into oligogalacturonates (UGA), which are continuously extracted from the tank. A mathematical model of our system predicted that the conversion efficiency of PGA into UGA increases in a range of coefficients of dilution until reaching an upper limit where the fraction of UGA that is extracted from the bioreactor is maximized. Results from experiments with a continuous reactor hosting a strain of the plant pathogenic bacterium Dickeya dadantii and in which the dilution coefficients were varied quantitatively validated the predictions of our model. A further theoretical analysis of the system enabled an a priori comparison of the efficiency of eight other pectate lyase–producing microorganisms with that of D. dadantii. Our findings suggest that D. dadantii is the most efficient microorganism and therefore the best candidate for a practical implementation of our scheme for the bioproduction of UGA from PGA.

scholarly journals Characterization of the early response of Arabidopsis thaliana to Dickeya dadantii infection using expression profiling

2018 ◽  
Author(s):  
Frédérique Van Gijsegem ◽  
Frédérique Bitton ◽  
Anne-Laure Laborie ◽  
Yvan Kraepiel ◽  
Jacques Pédron
Keyword(s):  
Arabidopsis Thaliana ◽  
Early Stage ◽  
Plant Defence ◽  
Plant Responses ◽  
Type I ◽  
In Planta ◽  
Secretion Systems ◽  
Dickeya Dadantii ◽  
A Genome

AbstractTo draw a global view of plant responses to interactions with the phytopathogenic enterobacterale Dickeya dadantii, a causal agent of soft rot diseases on many plant species, we analysed the early Arabidopsis responses to D. dadantii infection. We performed a genome-wide analysis of the Arabidopsis thaliana transcriptome during D. dadantii infection and conducted a genetic study of identified responses.A limited set of genes related to plant defence or interactions with the environment were induced at an early stage of infection, with an over-representation of genes involved in both the metabolism of indole glucosinolates (IGs) and the jasmonate (JA) defence pathway. Bacterial type I and type II secretion systems are required to trigger the induction of IG and JA-related genes while the type III secretion system appears to partially inhibit these defence pathways. Using Arabidopsis mutants impaired in JA biosynthesis or perception, we showed that induction of some IG metabolism genes was COI1-dependent but, surprisingly, JA-independent. Moreover, characterisation of D. dadantii disease progression in Arabidopsis mutants impaired in JA or IG pathways showed that JA triggers an efficient plant defence response that does not involve IGs.The induction of the IG pathway by bacterial pathogens has been reported several times in vitro. This study shows for the first time, that this induction does indeed occur in planta, but also that this line of defence is ineffective against D. dadantii infection, in contrast to its role to counteract herbivorous or fungal pathogen attacks.

Reservoirs of resistance: polymyxin resistance in veterinary-associated companion animal isolates of Pseudomonas aeruginosa

2019 ◽  
Vol 185 (7) ◽  
pp. 206-206 ◽  
Author(s):  
Andrea Scott ◽  
Sian Pottenger ◽  
Dorina Timofte ◽  
Matthew Moore ◽  
Laura Wright ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Pathogenic Bacteria ◽  
Inhibitory Concentration ◽  
Respiratory Infections ◽  
Companion Animals ◽  
Opportunistic Pathogen ◽  
Polymyxin B ◽  
Potential Reservoir ◽  
Human Infections ◽  
Animal Isolates

BackgroundPseudomonas aeruginosa is an opportunistic pathogen and a major cause of infections. Widespread resistance in human infections are increasing the use of last resort antimicrobials such as polymyxins. However, these have been used for decades in veterinary medicine. Companion animals are an understudied source of antimicrobial resistant P. aeruginosa isolates. This study evaluated the susceptibility of P. aeruginosa veterinary isolates to polymyxins to determine whether the veterinary niche represents a potential reservoir of resistance genes for pathogenic bacteria in both animals and humans.Methods and resultsClinical P. aeruginosa isolates (n=24) from UK companion animals were compared for antimicrobial susceptibility to a panel of human-associated isolates (n=37). Minimum inhibitory concentration (MIC) values for polymyxin B and colistin in the companion animals was significantly higher than in human isolates (P=0.033 and P=0.013, respectively). Genotyping revealed that the veterinary isolates were spread throughout the P. aeruginosa population, with shared array types from human infections such as keratitis and respiratory infections, suggesting the potential for zoonotic transmission. Whole genome sequencing revealed mutations in genes associated with polymyxin resistance and other antimicrobial resistance-related genes.ConclusionThe high levels of resistance to polymyxin shown here, along with genetic similarities between some human and animal isolates, together suggest a need for sustained surveillance of this veterinary niche as a potential reservoir for resistant, clinically relevant bacteria in both animals and humans.

scholarly journals phgABC, a Three-Gene Operon Required for Growth of Streptococcus pneumoniae in Hyperosmotic Medium and In Vivo

2004 ◽  
Vol 72 (8) ◽  
pp. 4579-4588 ◽  
Author(s):  
Jeremy S. Brown ◽  
Sarah M. Gilliland ◽  
Shilpa Basavanna ◽  
David W. Holden
Keyword(s):  
Streptococcus Pneumoniae ◽  
Mutant Strain ◽  
Compatible Solutes ◽  
Wild Type ◽  
Gram Positive Bacteria ◽  
Mutant Strains ◽  
Increased Sensitivity ◽  
Related Proteins ◽  
And Oxidative Stress

ABSTRACT To cause disease, bacterial pathogens need to be able to adapt to the physiological conditions found within the host, including an osmolality of approximately 290 mosmol kg−1. While investigating Streptococcus pneumoniae genes contained within pneumococcal pathogenicity island 1, we identified a three-gene operon of unknown function termed phgABC. PhgC has a domain with similarity to diacylglycerol kinases of eukaryotes and is the first described member of a family of related proteins found in many gram-positive bacteria. phgA and phgC mutant strains were constructed by insertional duplication mutagenesis and found to have impaired growth under conditions of high osmotic and oxidative stress. The compatible solutes proline and glycine betaine improved growth of the wild-type and the phgA mutant strains in hyperosmolar medium, and when analyzed by electron microscopy, the cellular morphology of the phgA mutant strain was unaffected by osmotic stress. The phgA and phgC mutant strains were reduced in virulence in models of both systemic and pulmonary infection. As the virulence of the phgA mutant strain was not restored in gp91phox−/− mice and the phgA and phgC mutant strains had reduced growth in both blood and serum, the reduced virulence of these strains is unlikely to be due to increased sensitivity to the respiratory burst of phagocytes but is, instead, due to impaired growth at physiological osmolality.

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