scholarly journals Sucrose-dependence of sugar uptake, quorum sensing and virulence of the rice blight pathogen Xanthomonas oryzae pv. oryzae

2021 ◽  
Author(s):  
Juying Long ◽  
Mayuri Sadoine ◽  
Confeng Song ◽  
Yugander Arra ◽  
Wolf B Frommer ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Extracellular Polysaccharide ◽  
Sigma Factors ◽  
Xanthomonas Oryzae ◽  
Host Cells ◽  
Sugar Uptake ◽  
Sucrose Supply ◽  
Necessary And Sufficient ◽  
Rate Limiting

Virulence of Xanthomonas oryzae pv. oryzae (Xoo), which causes bacterial leaf blight of rice, depends on induction of host SWEET sucrose efflux transporters. It remained unknown whether secreted sucrose serves bacterial nutrition or host defense. Here we identified the sux sucrose uptake/utilization locus of Xoo and demonstrate that it is necessary and sufficient for sucrose acquisition. Induction of sux genes during infection closely tracked induction of rice SWEET11a. sux mutants were defective in swimming, swarming, extracellular polysaccharide (EPS) production and biofilm formation. EPS synthesis in mutants was restored by the quorum-sensing factor DSF. Notably, transcripts for rate limiting steps in DSF production were unaffected by sucrose, transcripts of the DSF receptor were sucrose-inducible and increased during infection, indicating sensitization to DSF in response to sucrose supply. Sucrose induced the sigma factors transcripts for RpoN1 and RpoN2 that regulate swimming, EPS and virulence. Furthermore, in contrast to Xanthomonas axonopodis pv. manihotis, virulence of Xoo depended critically on sux gene function. Together, pathogen-induced sucrose efflux from host cells likely induces bacterial sigma factors and sensitizes quorum signaling necessary for biofilm formation and colonization of the xylem, serves as energy source for swimming against the xylem stream, and as nutrient for growth.

scholarly journals The Role of a Host-Induced Arginase of Xanthomonas oryzae pv. oryzae in Promoting Virulence on Rice

2019 ◽  
Vol 109 (11) ◽  
pp. 1869-1877
Author(s):  
Yuqiang Zhang ◽  
Guichun Wu ◽  
Ian Palmer ◽  
Bo Wang ◽  
Guoliang Qian ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Bacterial Blight ◽  
Wild Type Strain ◽  
Bacterial Pathogen ◽  
Extracellular Polysaccharide ◽  
Rice Cultivar ◽  
Xanthomonas Oryzae ◽  
Wild Type ◽  
Bacterial Blight Of Rice

The plant bacterial pathogen Xanthomonas oryzae pv. oryzae causes bacterial blight of rice, which is one of the most destructive rice diseases prevalent in Asia and parts of Africa. Despite many years of research, how X. oryzae pv. oryzae causes bacterial blight of rice is still not completely understood. Here, we show that the loss of the rocF gene caused a significant decrease in the virulence of X. oryzae pv. oryzae in the susceptible rice cultivar IR24. Bioinformatics analysis demonstrated that rocF encodes arginase. Quantitative real-time PCR and Western blot assays revealed that rocF expression was significantly induced by rice and arginine. The rocF deletion mutant strain showed elevated sensitivity to hydrogen peroxide, reduced extracellular polysaccharide (EPS) production, and reduced biofilm formation, all of which are important determinants for the full virulence of X. oryzae pv. oryzae, compared with the wild-type strain. Taken together, the results of this study revealed a mechanism by which a bacterial arginase is required for the full virulence of X. oryzae pv. oryzae on rice because of its contribution to tolerance to reactive oxygen species, EPS production, and biofilm formation.

scholarly journals Cephalosporins target quorum sensing and suppress virulence of Pseudomonas aeruginosa in Caenorhabditis elegans infection model

2020 ◽  
Author(s):  
Lokender Kumar ◽  
Nathanael Brenner ◽  
John Brice ◽  
Judith Klein-Seetharaman ◽  
Susanta K. Sarkar
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Caenorhabditis Elegans ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Host Cells ◽  
Infection Model ◽  
Host Immune System ◽  
Bacterial Cells

ABSTRACTPseudomonas aeruginosa utilizes a chemical social networking system referred to as quorum sensing (QS) to strategically co-ordinate the expression of virulence factors and biofilm formation. Virulence attributes damage the host cells, impair the host immune system, and protect bacterial cells from antibiotic attack. Thus, anti-QS agents may act as novel anti-infective therapeutics to treat P. aeruginosa infections. The present study was performed to evaluate the anti-QS, anti-biofilm, and anti-virulence activity of β-lactam antibiotics (carbapenems and cephalosporins) against P. aeruginosa. The anti-QS activity was quantified using Chromobacterium violaceum CV026 as a QS reporter strain. Our results showed that cephalosporins including cefepime (CP), ceftazidime (CF), and ceftriaxone (CT) exhibited potent anti-QS and anti-virulence activities against P. aeruginosa PAO1. These antibiotics significantly impaired motility phenotypes, decreased pyocyanin production, and reduced the biofilm formation by P. aeruginosa PAO1. In the present study, we studied isogenic QS mutants of PAO1: ΔLasR, ΔRhlR, ΔPqsA, and ΔPqsR and found that the levels of virulence factors of antibiotic-treated PAO1 were comparable to QS mutant strains. Molecular docking predicted high binding affinities of cephalosporins for the ligand-binding pocket of QS receptors (CviR, LasR, and PqsR). In addition, our results showed that the anti-microbial activity of aminoglycosides increased in the presence of sub-inhibitory concentrations (sub-MICs) of CP against P. aeruginosa PAO1. Further, utilizing Caenorhabditis elegans as an animal model for the in vivo anti-virulence effects of antibiotics, cephalosporins showed a significant increase in C. elegans survival by suppressing virulence factor production in P. aeruginosa. Thus, our results indicate that cephalosporins might provide a viable anti-virulence therapy in the treatment of infections caused by multi-drug resistant P. aeruginosa.

scholarly journals Identification and Characterization of a Novel Gene, hshB, in Xanthomonas oryzae pv. oryzicola Co-Regulated by Quorum Sensing and clp

2012 ◽  
Vol 102 (3) ◽  
pp. 252-259 ◽  
Author(s):  
Yancun Zhao ◽  
Guoliang Qian ◽  
Jiaqin Fan ◽  
Fangqun Yin ◽  
Yijin Zhou ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Extracellular Polysaccharide ◽  
Bioinformatic Analysis ◽  
Xanthomonas Oryzae ◽  
Pcr Analysis ◽  
Homologous Gene ◽  
Upstream Gene ◽  
Novel Gene ◽  
Putative Signal Peptide ◽  
Diffusible Signal Factor

Virulence factors of Xanthomonas oryzae pv. oryzicola, the causal agent of bacterial leaf streak in rice, are regulated by a diffusible signal factor (DSF)-dependent quorum-sensing (QS) system. In this study, a novel pathogenicity-related gene, Xoryp_010100018570 (named hshB), of X. oryzae pv. oryzicola was characterized. hshB encodes a hydrolase with a putative signal peptide, which is a homolog of imidazolonepropionase. Bioinformatic analysis showed that hshB is relatively conserved in the genus Xanthomonas but the homologous gene of hshB was not found in X. oryzae pv. oryzae. Reverse-transcription polymerase chain reaction (PCR) analysis showed that hshB and its upstream gene, Xoryp_010100018565 (named hshA), are co-transcribed in X. oryzae pv. oryzicola. Subsequent experimental results indicated that mutation of hshB remarkably impaired the virulence, extracellular protease activity, extracellular polysaccharide production, growth in minimal medium, and resistance to oxidative stress and bismerthiazol of X. oryzae pv. oryzicola. Mutation of clp, encoding a global regulator, resulted in similar phenotypes. Real-time PCR assays showed that hshB transcription is positively regulated by clp and DSF, and induced by poor nutrition. Our study not only found a novel gene hshB regulated by DSF-dependent QS system and clp but also showed that hshB was required for virulence of X. oryzae pv. oryzicola.

scholarly journals The RpfB-Dependent Quorum Sensing Signal Turnover System Is Required for Adaptation and Virulence in Rice Bacterial Blight Pathogen Xanthomonas oryzae pv. oryzae

2016 ◽  
Vol 29 (3) ◽  
pp. 220-230 ◽  
Author(s):  
Xing-Yu Wang ◽  
Lian Zhou ◽  
Jun Yang ◽  
Guang-Hai Ji ◽  
Ya-Wen He
Keyword(s):  
Quorum Sensing ◽  
Bacterial Blight ◽  
Xanthomonas Campestris ◽  
Deletion Mutant ◽  
Extracellular Polysaccharide ◽  
Xanthomonas Oryzae ◽  
Rice Bacterial Blight ◽  
Double Deletion ◽  
Diffusible Signal Factor ◽  
Bacterial Blight Pathogen

Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, produces diffusible signal factor (DSF) family quorum sensing signals to regulate virulence. The biosynthesis and perception of DSF family signals require components of the rpf (regulation of pathogenicity factors) cluster. In this study, we report that RpfB plays an essential role in DSF family signal turnover in X. oryzae pv. oryzae PXO99A. The production of DSF family signals was boosted by deletion of the rpfB gene and was abolished by its overexpression. The RpfC/RpfG-mediated DSF signaling system negatively regulates rpfB expression via the global transcription regulator Clp, whose activity is reversible in the presence of cyclic diguanylate monophosphate. These findings indicate that the DSF family signal turnover system in PXO99A is generally consistent with that in Xanthomonas campestris pv. campestris. Moreover, this study has revealed several specific roles of RpfB in PXO99A. First, the rpfB deletion mutant produced high levels of DSF family signals but reduced extracellular polysaccharide production, extracellular amylase activity, and attenuated pathogenicity. Second, the rpfB/rpfC double-deletion mutant was partially deficient in xanthomonadin production. Taken together, the RpfB-dependent DSF family signal turnover system is a conserved and naturally presenting signal turnover system in Xanthomonas spp., which plays unique roles in X. oryzae pv. oryzae adaptation and pathogenesis.

scholarly journals CRISPR-cas3 of Salmonella Upregulates Bacterial Biofilm Formation and Virulence to Host Cells by Targeting Quorum-Sensing Systems

Pathogens ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 53 ◽  
Author(s):  
Luqing Cui ◽  
Xiangru Wang ◽  
Deyu Huang ◽  
Yue Zhao ◽  
Jiawei Feng ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Bacterial Biofilm ◽  
Host Cells ◽  
Microbial Pathogens ◽  
Bacterial Invasion ◽  
Type I ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Sensing Systems ◽  
Type Three Secretion System

Salmonella is recognized as one of the most common microbial pathogens worldwide. The bacterium contains the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems, providing adaptive immunity against invading foreign nucleic acids. Previous studies suggested that certain bacteria employ the Cas proteins of CRISPR-Cas systems to target their own genes, which also alters the virulence during invasion of mammals. However, whether CRISPR-Cas systems in Salmonella have similar functions during bacterial invasion of host cells remains unknown. Here, we systematically analyzed the genes that are regulated by Cas3 in a type I-E CRISPR-Cas system and the virulence changes due to the deletion of cas3 in Salmonella enterica serovar Enteritidis. Compared to the cas3 gene wild-type (cas3 WT) Salmonella strain, cas3 deletion upregulated the lsrFGBE genes in lsr (luxS regulated) operon related to quorum sensing (QS) and downregulated biofilm-forming-related genes and Salmonella pathogenicity island 1 (SPI-1) genes related to the type three secretion system (T3SS). Consistently, the biofilm formation ability was downregulated in the cas3 deletion mutant (Δcas3). The bacterial invasive and intracellular capacity of Δcas3 to host cells was also reduced, thereby increasing the survival of infected host cells and live chickens. By the transcriptome-wide screen (RNA-Seq), we found that the cas3 gene impacts a series of genes related to QS, the flagellum, and SPI-1-T3SS system, thereby altering the virulence phenotypes. As QS SPI-1-T3SS and CRISPR-Cas systems are widely distributed in the bacteria kingdom, our findings extend our understanding of virulence regulation and pathogenicity in mammalian hosts for Salmonella and potentially other bacteria.

scholarly journals Inhibition of Virulence Factors and Biofilm Formation by Wogonin Attenuates Pathogenicity of Pseudomonas aeruginosa PAO1 via Targeting pqs Quorum-Sensing System

2021 ◽  
Vol 22 (23) ◽  
pp. 12699
Author(s):  
Shiwei Wang ◽  
Yuqi Feng ◽  
Xiaofeng Han ◽  
Xinyu Cai ◽  
Liu Yang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Extracellular Polysaccharide ◽  
Fruit Fly ◽  
Opportunistic Pathogen ◽  
Signal Molecule ◽  
Conventional Antibiotics

Pseudomonas aeruginosa, an important opportunistic pathogen, is capable of producing various virulence factors and forming biofilm that are regulated by quorum sensing (QS). It is known that targeting virulence factor production and biofilm formation instead of exerting selective pressure on growth such as conventional antibiotics can reduce multidrug resistance in bacteria. Therefore, many quorum-sensing inhibitors (QSIs) have been developed to prevent or treat this bacterial infection. In this study, wogonin, as an active ingredient from Agrimonia pilosa, was found to be able to inhibit QS system of P. aeruginosa PAO1. Wogonin downregulated the expression of QS-related genes and reduced the production of many virulence factors, such as elastase, pyocyanin, and proteolytic enzyme. In addition, wogonin decreased the extracellular polysaccharide synthesis and inhibited twitching, swimming, and swarming motilities and biofilm formation. The attenuation of pathogenicity in P. aeruginosa PAO1 by wogonin application was further validated in vivo by cabbage infection and fruit fly and nematode survival experiments. Further molecular docking analysis, pathogenicity examination of various QS-related mutants, and PQS signal molecule detection revealed that wogonin could interfere with PQS signal molecular synthesis by affecting pqsA and pqsR. Taken together, the results indicated that wogonin might be used as an anti-QS candidate drug to attenuate the infection caused by P. aeruginosa.

Expression of Pseudomonas aeruginosa exoS is controlled by quorum sensing and RpoS

Microbiology ◽  
2004 ◽  
Vol 150 (4) ◽  
pp. 843-851 ◽  
Author(s):  
Michael Hogardt ◽  
Maximilian Roeder ◽  
Anna Maria Schreff ◽  
Leo Eberl ◽  
Jürgen Heesemann
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Homoserine Lactone ◽  
Host Cells ◽  
Regulatory Control ◽  
Reasonable Assumption ◽  
Virulence Determinants ◽  
Exoenzyme S ◽  
Regulatory Cascade

In Pseudomonas aeruginosa, virulence determinants and biofilm formation are coordinated via a hierarchical quorum sensing cascade, which involves the transcriptional regulators LasR and RhlR and their cognate homoserine lactone activators C12-HSL [N-(3-oxododecanoyl)-l-homoserine lactone] and c4-hsl (n-butanoyl-l-homoserine lactone), which are produced by LasI and RhlI, respectively. The exoenzyme S regulon of P. aeruginosa, comprises genes for a type III secretion system and for four anti-host effector proteins (ExoS, T, U and Y), which are translocated into host cells. It is a reasonable assumption that this ExoS regulon should be downregulated in the biofilm growth state and thus should also be under the regulatory control of the Las/Rhl system. Therefore, an exoS′-gfp reporter construct was used, and the influence of the Las and Rhl quorum sensing systems and the effect of the stationary-phase sigma factor RpoS on regulation of the exoS gene was examined. Evidence is provided for downregulation of exoS during biofilm formation of P. aeruginosa PAO1. The rhlI mutant PDO100 and rhlR mutant PDO111, but not the lasI mutant PDO-JP1, showed approximately twofold upregulation of the exoS′-gfp reporter in comparison to PAO1. Upregulation of exoS′-gfp in the PDO100 mutant could be repressed to normal level by adding C4-HSL autoinducer, indicating a negative regulatory effect of RhlR/C4-HSL on exoS expression. As RhlR/C4-HSL is also involved in regulation of RpoS, the P. aeruginosa rpoS mutant SS24 was examined and the exoS′-gfp reporter was found to be fivefold upregulated in comparison to PAO1. For the first time evidence is reported for a regulatory cascade linking RhlR/RhlI and RpoS with the expression of the anti-host effector ExoS, part of the exoenzyme S regulon. Moreover, these data suggest that the exoenzyme S regulon may be downregulated in P. aeruginosa biofilms.

Quorum Sensing – A Stratagem for Conquering Multi-Drug Resistant Pathogens

2020 ◽  
Vol 26 ◽  
Author(s):  
Madison Tonkin ◽  
Shama Khan ◽  
Mohmmad Younus Wani ◽  
Aijaz Ahmad
Keyword(s):  
Drug Resistance ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Cell Communication ◽  
Natural Compounds ◽  
Quorum Sensing Inhibitors ◽  
Communication Technique ◽  
Multicellular Organisms ◽  
Chemical Strategies

: Quorum sensing is defined as cell to cell communication between microorganisms, which enables microorganisms to behave as multicellular organisms. Quorum sensing enables many collaborative benefits such as synchronisation of virulence factors and biofilm formation. Both quorum sensing as well as biofilm formation encourage the development of drug resistance in microorganisms. Biofilm formation and quorum sensing are causally linked to each other and play role in the pathogenesis of microorganisms. With the increasing drug resistance against the available antibiotics and antifungal medications, scientists are combining different options to develop new strategies. Such strategies rely on the inhibition of the communication and virulence factors rather than on killing or inhibiting the growth of the microorganisms. This review encompasses the communication technique used by microorganisms, how microorganism resistance is linked to quorum sensing and various chemical strategies to combat quorum sensing and thereby drug resistance. Several compounds have been identified as quorum sensing inhibitors and are known to be effective in reducing resistance as they do not kill the pathogens but rather disrupt their communication. Natural compounds have been identified as anti-quorum sensing agents. However, natural compounds present several related disadvantages. Therefore, the need for the development of synthetic or semi-synthetic compounds has arisen. This review argues that anti-quorum sensing compounds are effective in disrupting quorum sensing and could therefore be effective in reducing microorganism drug resistance.

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