mRNA-Seq reveals the quorum sensing system luxS gene contributes to the environmental fitness of Streptococcus suis type 2

Abstract Background Streptococcus suis type 2 (SS2) is an important zoonotic pathogen. We have previously reported the structure of LuxS protein and found that the luxS gene is closely related to biofilm, virulence gene expression and drug resistance of SS2. However, the mechanism of luxS mediated SS2 stress response is unclear. Therefore, this experiment performed stress response to luxS mutant (ΔluxS) and complement strain (CΔluxS), overexpression strain (luxS+) and wild-type SS2 strain HA9801, and analyzed the differential phenotypes in combination with transcriptome data. Results The results indicate that the luxS gene deletion causes a wide range of phenotypic changes, including chain length. RNA sequencing identified 278 lx-regulated genes, of which 179 were up-regulated and 99 were down-regulated. Differential genes focus on bacterial growth, stress response, metabolic mechanisms and drug tolerance. Multiple mitotic genes were down-regulated; while the ABC transporter system genes, cobalamin /Fe3+-iron carrier ABC transporter ATPase and oxidative stress regulators were up-regulated. The inactivation of the luxS gene caused a significant reduction in the growth and survival in the acid (pH = 3.0, 4.0, 5.0) and iron (100 mM iron chelator 2,2′-dipyridyl) stress environments. However, the mutant strain ΔluxS showed increased antioxidant activity to H2O2 (58.8 mmol/L). Conclusions The luxS gene in SS2 appears to play roles in iron metabolism and protective responses to acidic and oxidative environmental conditions.

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The quorum sensing system luxS gene contributes to the environmental fitness of Streptococcus suis

10.21203/rs.3.rs-93208/v1 ◽

2020 ◽

Author(s):

Jinpeng Li ◽

Yuxin Wang ◽

Yanbin Du ◽

Hui Zhang ◽

Qingyin Fan ◽

...

Keyword(s):

Stress Response ◽

Abc Transporter ◽

Virulence Gene ◽

Streptococcus Suis ◽

Growth Stress ◽

Growth And Survival ◽

Virulence Gene Expression ◽

Overexpression Strain ◽

Wide Range ◽

And Oxidative Stress

Abstract Background: Streptococcus suis type 2 (SS2) is an important zoonotic pathogen. We have previously reported the structure of LuxS protein and found that the luxS gene is closely related to biofilm, virulence gene expression and drug resistance of SS2. However, the mechanism of luxS mediated SS2 stress response is unclear. Therefore, this experiment performed stress response to luxS mutant (ΔluxS) and complement strain (CΔluxS), overexpression strain (luxS+) and wild-type SS2 strain HA9801, and analyzed the differential phenotypes in combination with transcriptome data.Results: The results indicate that the luxS gene causes a wide range of phenotypic changes, including chain length. RNA sequencing identified 278 luxS-regulated genes, of which 179 were up-regulated and 99 were down-regulated. Differential genes focus on bacterial growth, stress response, metabolic mechanisms and drug tolerance. Multiple mitotic genes were down-regulated; while the ABC transporter system genes, cobalamin /Fe3+-iron carrier ABC transporter ATPase and oxidative stress regulators were up-regulated. The inactivation of the luxS gene caused a significant reduction in the growth and survival in the acid and iron stress environments. However, the mutant strain ΔluxS showed increased antioxidant activity to H2O2. Conclusions: The luxS gene in SS2 appears to play roles in iron metabolism and protective responses to acidic and oxidative environmental conditions.

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Norfloxacin Sub-Inhibitory Concentration Affects Streptococcus suis Biofilm Formation and Virulence Gene Expression

Indian Journal of Animal Research ◽

10.18805/ijar.b-1192 ◽

2020 ◽

Author(s):

Baobao Li ◽

Li Yi ◽

Jinpeng Li ◽

Shenglong Gong ◽

Xiao Dong ◽

...

Keyword(s):

Gene Expression ◽

Biofilm Formation ◽

Inhibitory Concentration ◽

Mrna Level ◽

Virulence Gene ◽

Streptococcus Suis ◽

Economic Losses ◽

Swine Industry ◽

Virulence Gene Expression ◽

Viable Bacteria

Streptococcus suis (S. suis) is a major pathogen causing economic losses to the swine industry. Norfloxacins are usually used at sub-MIC (Minimum Inhibitory Concentration) doses to prevent S. suis infection. This study demonstrates the effect of norfloxacin sub-MIC on biofilm formation and virulence gene expression in S. suis.It was found that 1/4 MIC of norfloxacin increased biofilm formation in S. suis, the biofilms formed contained a higher number of viable bacteria. Additionally, bacterial growth rates were inhibited at 1/2 MIC of norfloxacin. Furthermore, the mRNA level of S. suis virulence gene cps, ef, sly, fpbs, gdh and gapdh increased by real-time PCR, while the virulence gene mrp decreased at 1/4 MIC. In conclusion, Norfloxacin sub-MICs affects biofilm formation and virulence gene expression in S. suis. These findings suggest that investigating the effect of the administration of antibiotics sub-MICs on bacterial biofilms and infection may lead to the development of future antibiotic treatments modalities.

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Listeria monocytogenes σB Regulates Stress Response and Virulence Functions

Journal of Bacteriology ◽

10.1128/jb.185.19.5722-5734.2003 ◽

2003 ◽

Vol 185 (19) ◽

pp. 5722-5734 ◽

Cited By ~ 246

Author(s):

Mark J. Kazmierczak ◽

Sharon C. Mithoe ◽

Kathryn J. Boor ◽

Martin Wiedmann

Keyword(s):

Gene Expression ◽

Listeria Monocytogenes ◽

Stress Response ◽

Consensus Sequence ◽

Virulence Gene ◽

Wild Type ◽

Promoter Regions ◽

Virulence Gene Expression ◽

Stress Response Genes ◽

In The Wild

ABSTRACT While the stress-responsive alternative sigma factor σB has been identified in different species of Bacillus, Listeria, and Staphylococcus, theσ B regulon has been extensively characterized only in B. subtilis. We combined biocomputing and microarray-based strategies to identify σB-dependent genes in the facultative intracellular pathogen Listeria monocytogenes. Hidden Markov model (HMM)-based searches identified 170 candidateσ B-dependent promoter sequences in the strain EGD-e genome sequence. These data were used to develop a specialized, 208-gene microarray, which included 166 genes downstream of HMM-predicted σB-dependent promoters as well as selected virulence and stress response genes. RNA for the microarray experiments was isolated from both wild-type and ΔsigB null mutant L. monocytogenes cells grown to stationary phase or exposed to osmotic stress (0.5 M KCl). Microarray analyses identified a total of 55 genes with statistically significantσ B-dependent expression under the conditions used in these experiments, with at least 1.5-fold-higher expression in the wild type over the sigB mutant under either stress condition (51 genes showed at least 2.0-fold-higher expression in the wild type). Of the 55 genes exhibiting σB-dependent expression, 54 were preceded by a sequence resembling the σB promoter consensus sequence. Rapid amplification of cDNA ends-PCR was used to confirm the σB-dependent nature of a subset of eight selected promoter regions. Notably, theσ B-dependent L. monocytogenes genes identified through this HMM/microarray strategy included both stress response genes (e.g., gadB, ctc, and the glutathione reductase gene lmo1433) and virulence genes (e.g., inlA, inlB, and bsh). Our data demonstrate that, in addition to regulating expression of genes important for survival under environmental stress conditions, σB also contributes to regulation of virulence gene expression in L. monocytogenes. These findings strongly suggest thatσ B contributes to L. monocytogenes gene expression during infection.

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Carbohydrate Availability Regulates Virulence Gene Expression in Streptococcus suis

PLoS ONE ◽

10.1371/journal.pone.0089334 ◽

2014 ◽

Vol 9 (3) ◽

pp. e89334 ◽

Cited By ~ 24

Author(s):

M. Laura Ferrando ◽

Peter van Baarlen ◽

Germano Orrù ◽

Rosaria Piga ◽

Roger S. Bongers ◽

...

Keyword(s):

Gene Expression ◽

Virulence Gene ◽

Streptococcus Suis ◽

Virulence Gene Expression ◽

Carbohydrate Availability

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Role for sagA and siaA in Quorum Sensing and Iron Regulation in Streptococcus pyogenes

Infection and Immunity ◽

10.1128/iai.01824-06 ◽

2007 ◽

Vol 75 (10) ◽

pp. 5011-5017 ◽

Cited By ~ 8

Author(s):

Kowthar Y. Salim ◽

Joyce C. de Azavedo ◽

Darrin J. Bast ◽

Dennis G. Cvitkovitch

Keyword(s):

Quorum Sensing ◽

Streptococcus Pyogenes ◽

Iron Acquisition ◽

Virulence Gene ◽

Wild Type ◽

Virulence Gene Expression ◽

Streptolysin S ◽

Wide Range ◽

Cell Densities ◽

The Many

ABSTRACT Streptococcus pyogenes is a ubiquitous and versatile pathogen that causes a variety of infections with a wide range of severity. The versatility of this organism is due in part to its capacity to regulate virulence gene expression in response to the many environments that it encounters during an infection. We analyzed the expression of two potential virulence factors, sagA and siaA (also referred to as pel and htsA, respectively), in response to conditions of varying cell densities and iron concentrations. The sagA gene was up-regulated in conditioned medium from a wild-type strain but not from sagA-deficient mutants, and the gene was also up-regulated in the presence of streptolysin S (SLS), the gene product of sagA, thus indicating that this gene or its product is involved in density-dependent regulation of S. pyogenes. By comparison, siaA responded in a manner consistent with a role in iron acquisition since it was up-regulated under iron-restricted conditions. Although siaA expression was also up-regulated in the presence of SLS and in conditioned media from both wild-type and sagA-deficient mutants, this up-regulation was not growth phase dependent. We conclude that sagA encodes a quorum-sensing signaling molecule, likely SLS, and further support the notion that siaA is likely involved in iron acquisition.

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The Tzs Protein and Exogenous Cytokinin Affect Virulence Gene Expression and Bacterial Growth of Agrobacterium tumefaciens

Phytopathology ◽

10.1094/phyto-01-13-0020-r ◽

2013 ◽

Vol 103 (9) ◽

pp. 888-899 ◽

Cited By ~ 16

Author(s):

Hau-Hsuan Hwang ◽

Fong-Jhih Yang ◽

Tun-Fang Cheng ◽

Yi-Chun Chen ◽

Ying-Ling Lee ◽

...

Keyword(s):

Gene Expression ◽

Agrobacterium Tumefaciens ◽

Bacterial Growth ◽

Deletion Mutant ◽

Virulence Gene ◽

Protein Accumulation ◽

Virulence Gene Expression ◽

Crown Gall Disease ◽

Wide Range ◽

Exogenous Cytokinin

The soil phytopathogen Agrobacterium tumefaciens causes crown gall disease in a wide range of plant species. The neoplastic growth at the infection sites is caused by transferring, integrating, and expressing transfer DNA (T-DNA) from A. tumefaciens into plant cells. A trans-zeatin synthesizing (tzs) gene is located in the nopaline-type tumor-inducing plasmid and causes trans-zeatin production in A. tumefaciens. Similar to known virulence (Vir) proteins that are induced by the vir gene inducer acetosyringone (AS) at acidic pH 5.5, Tzs protein is highly induced by AS under this growth condition but also constitutively expressed and moderately upregulated by AS at neutral pH 7.0. We found that the promoter activities and protein levels of several AS-induced vir genes increased in the tzs deletion mutant, a mutant with decreased tumorigenesis and transient transformation efficiencies, in Arabidopsis roots. During AS induction and infection of Arabidopsis roots, the tzs deletion mutant conferred impaired growth, which could be rescued by genetic complementation and supplementing exogenous cytokinin. Exogenous cytokinin also repressed vir promoter activities and Vir protein accumulation in both the wild-type and tzs mutant bacteria with AS induction. Thus, the tzs gene or its product, cytokinin, may be involved in regulating AS-induced vir gene expression and, therefore, affect bacterial growth and virulence during A. tumefaciens infection.

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Characterization of the roles of activated charcoal and Chelex in the induction of PrfA regulon expression in complex medium

PLoS ONE ◽

10.1371/journal.pone.0250989 ◽

2021 ◽

Vol 16 (4) ◽

pp. e0250989

Author(s):

Ahmed Gaballa ◽

Sriya Sunil ◽

Etienne Doll ◽

Sarah I. Murphy ◽

Tyler Bechtel ◽

...

Keyword(s):

Gene Expression ◽

Activated Charcoal ◽

Metal Ion ◽

Expression Patterns ◽

Brain Heart Infusion ◽

Virulence Gene ◽

Listeriolysin O ◽

Virulence Gene Expression ◽

Wide Range ◽

Regulated Gene Expression

The foodborne pathogen Listeria monocytogenes is able to survive across a wide range of intra- and extra-host environments by appropriately modulating gene expression patterns in response to different stimuli. Positive Regulatory Factor A (PrfA) is the major transcriptional regulator of virulence gene expression in L. monocytogenes. It has long been known that activated charcoal is required to induce the expression of PrfA-regulated genes in complex media, such as Brain Heart Infusion (BHI), but not in chemically defined media. In this study, we show that the expression of the PrfA-regulated hly, which encodes listeriolysin O, is induced 5- and 8-fold in L. monocytogenes cells grown in Chelex-treated BHI (Ch-BHI) and in the presence of activated charcoal (AC-BHI), respectively, relative to cells grown in BHI medium. Specifically, we show that metal ions present in BHI broth plays a role in the reduced expression of the PrfA regulon. In addition, we show that expression of hly is induced when the levels of bioavailable extra- or intercellular iron are reduced. L. monocytogenes cells grown Ch-BHI and AC-BHI media showed similar levels of resistance to the iron-activated antibiotic, streptonigrin, indicating that activated charcoal reduces the intracellular labile iron pool. Metal depletion and exogenously added glutathione contributed synergistically to PrfA-regulated gene expression since glutathione further increased hly expression in metal-depleted BHI but not in BHI medium. Analyses of transcriptional reporter fusion expression patterns revealed that genes in the PrfA regulon are differentially expressed in response to metal depletion, metal excess and exogenous glutathione. Our results suggest that metal ion abundance plays a role in modulating expression of PrfA-regulated virulence genes in L. monocytogenes.

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Morphological Alterations and Virulence Gene Expression of Listeria Monocytogenes Cells in Response to Gamma Irradiation Treatments

Nutrition and Food Processing ◽

10.31579/2637-8914/055 ◽

2021 ◽

Vol 04 (5) ◽

pp. 01-09

Author(s):

Hamouda Elabed

Keyword(s):

Gene Expression ◽

Fatty Acid ◽

Listeria Monocytogenes ◽

Gamma Irradiation ◽

Membrane Lipids ◽

Virulence Gene ◽

Morphological Alteration ◽

Morphological Alterations ◽

Virulence Gene Expression ◽

Wide Range

Gamma irradiation is one of the most popular ray treatments in food industry. It's used to control micro-organisms proliferation in a wide range of products however the response of bacteria to low doses is still unknown. In this study we mainly focus on morphological alteration and virulence gene expression in Listeria monocytogenes after gamma irradiation treatments. The atomic force micrographs (AFM) showed that 0.5 kGy dose has no effect on the membrane morphology of L. monocytogenes. However, after 0.7 kGy treatment, the cells lost their typical shape and smooth membrane and 1 kGy dose was totally destructive. Moreover, membrane fatty acid composition was analyzed by the chromatographic method after different gamma doses. Significant modifications on fatty acids composition were detected in the irradiated strain showing a novo synthesis of membrane lipids: C12:0; C14:0; C15:0; C16:0 and C18:0. In addition, we reported an increase of the saturated fatty acid, essential for membrane adaptation under stress conditions. The expression levels of three virulence genes (hlyA, fri and prfA) were studied in the same conditions using real-time PCR technique. The analysis revealed that both prfA and fri genes were up-regulated after gamma treatment. The induction of prfA, which is a regulator gene, may affect the expression other genes controlling the adaptive form in the treated strain. This study open prospects for further researches to explain the regulatory mechanisms of the adaptive response in Listeria monocytogenes when exposed to sublethal irradiation-stress.

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Relevance of Peptide Uptake Systems to the Physiology and Virulence of Streptococcus agalactiae

Journal of Bacteriology ◽

10.1128/jb.186.5.1398-1408.2004 ◽

2004 ◽

Vol 186 (5) ◽

pp. 1398-1408 ◽

Cited By ~ 46

Author(s):

Ulrike Samen ◽

Birgit Gottschalk ◽

Bernhard J. Eikmanns ◽

Dieter J. Reinscheid

Keyword(s):

Abc Transporter ◽

Streptococcus Agalactiae ◽

Virulence Gene ◽

Pcr Analysis ◽

Amniotic Cavity ◽

Virulence Gene Expression ◽

Reverse Transcription Pcr ◽

Virulence Traits ◽

Oligopeptide Permease ◽

Peptide Uptake

ABSTRACT Streptococcus agalactiae is a major cause of invasive infections in human newborns. To satisfy its growth requirements, S. agalactiae takes up 9 of the 20 proteinogenic amino acids from the environment. Defined S. agalactiae mutants in one or several of four putative peptide permease systems were constructed and tested for peptide uptake, growth in various media, and expression of virulence traits. Oligopeptide uptake by S. agalactiae was shown to be mediated by the ABC transporter OppA1-F, which possesses two substrate-binding proteins (OppA1 and OppA2) with overlapping substrate specificities. Dipeptides were found to be taken up in parallel by the oligopeptide permease OppA1-F, by the dipeptide ABC transporter DppA-E, and by the dipeptide symporter DpsA. Reverse transcription-PCR analysis revealed a polycistronic organization of the genes oppA1-F and dppA-E and a monocistronic organization of dpsA in S. agalactiae. The results of quantitative real-time PCR revealed a medium-dependent expression of the operons dppA-E and oppA1-F in S. agalactiae. Growth of S. agalactiae in human amniotic fluid was shown to require an intact dpsA gene, indicating an important role of DpsA during the infection of the amniotic cavity by S. agalactiae. Deletion of the oppB gene reduced the adherence of S. agalactiae to epithelial cells by 26%, impaired its adherence to fibrinogen and fibronectin by 42 and 33%, respectively, and caused a 35% reduction in expression of the fbsA gene, which encodes a fibrinogen-binding protein in S. agalactiae. These data indicate that the oligopeptide permease is involved in modulating virulence traits and virulence gene expression in S. agalactiae.

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The branched chain aminotransferase IlvE promotes growth, stress resistance and pathogenesis of Listeria monocytogenes

10.1101/2020.01.31.929828 ◽

2020 ◽

Cited By ~ 1

Author(s):

Karla D. Passalacqua ◽

Tianhui Zhou ◽

Tracy A. Washington ◽

Basel H. Abuaita ◽

Abraham L. Sonenshein ◽

...

Keyword(s):

Plasma Membrane ◽

Listeria Monocytogenes ◽

Stress Resistance ◽

Virulence Gene ◽

Optimal Growth ◽

Growth Stress ◽

Membrane Composition ◽

Virulence Gene Expression ◽

Absolute Requirement ◽

Branched Chain

ABSTRACTThe bacterial plasma membrane is a key interface during pathogen-host interactions, and membrane composition enhances resistance against host antimicrobial defenses. Branched chain fatty acids (BCFAs) are the major plasma membrane component in the intracellular Gram-positive pathogen Listeria monocytogenes (Lm) and BCFA metabolism is essential for Lm growth and virulence. BCFA synthesis requires branched chain amino acids (BCAAs), and the BCAA Isoleucine (Ile) is a necessary substrate for the predominant membrane anteiso-BCFAs (ai-BCFAs) as well as an environmental signal for virulence regulation in Lm. In this study, we explored how two proteins that metabolize or sense Ile contribute to Lm growth, BCFA metabolism, and virulence. The IlvE aminotransferase incorporates Ile into ai-BCFAs, while CodY is an Ile-sensing regulator that coordinates BCAA synthesis and virulence gene expression. Analysis of deletion mutants lacking IlvE (ΔilvE) or CodY (ΔcodY) revealed a major role for IlvE under nutrient restriction and stress conditions. Cultures of the ΔilvE mutant contained proportionally less ai-BCFAs relative to wild type, while of the ΔcodY mutant had a lower proportion of ai-BCFAs in stationary phase, despite containing more cell-associated Ile. Both ΔilvE and ΔcodY mutants required exogenous Ile for optimal growth, but the ΔilvE mutant had an absolute requirement for Valine and Leucine when Ile was absent. IlvE was also necessary for resistance to membrane stress, cell-to-cell spread, infection of primary macrophages, and virulence in mice. Our findings implicate IlvE as an integral aspect of Lm stress resistance and emphasize the central importance of Ile in Lm growth and virulence.

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