scholarly journals A Homolog of CcpA Mediates Catabolite Control in Listeria monocytogenes but Not Carbon Source Regulation of Virulence Genes

1998 ◽  
Vol 180 (23) ◽  
pp. 6316-6324 ◽  
Author(s):  
Jaideep Behari ◽  
Philip Youngman
Keyword(s):  
Listeria Monocytogenes ◽  
Carbon Source ◽  
Virulence Genes ◽  
Virulence Gene ◽  
Metabolic Enzyme ◽  
Virulence Gene Expression ◽  
Gram Positive Bacteria ◽  
Glucosidase Activity ◽  
Acid Protein ◽  
Catabolite Regulation

ABSTRACT Readily utilizable sugars down-regulate virulence gene expression in Listeria monocytogenes, which has led to the proposal that this regulation may be an aspect of global catabolite regulation (CR). We recently demonstrated that the metabolic enzyme α-glucosidase is under CR in L. monocytogenes. Here, we report the cloning and characterization from L. monocytogenes of an apparent ortholog of ccpA, which encodes an important mediator of CR in several low-G+C-content gram-positive bacteria. L. monocytogenes ccpA(ccpA Lm) is predicted to encode a 335-amino-acid protein with nearly 65% identity to the gene product ofBacillus subtilis ccpA (ccpA Bs). Southern blot analysis with a probe derived fromccpA Lm revealed a single strongly hybridizing band and also a second band of much lower intensity, suggesting that there may be other closely related sequences in the L. monocytogenes chromosome, as is the case in B. subtilis. Disruption of ccpA Lm resulted in the inability of the mutant to grow on glucose-containing minimal medium or increase its growth rate in the presence of preferred sugars, and it completely eliminated CR of α-glucosidase activity in liquid medium. However, α-glucosidase activity was only partially relieved from CR on solid medium. These results suggest that ccpA is an important element of carbon source regulation in L. monocytogenes. Nevertheless, utilizable sugars still down-regulate the expression of hly, which encodes the virulence factor hemolysin, in a ccpA Lm mutant, indicating that CcpA is not involved in carbon source regulation of virulence genes.

scholarly journals Regulation of hly Expression inListeria monocytogenes by Carbon Sources and pH Occurs through Separate Mechanisms Mediated by PrfA

1998 ◽  
Vol 66 (8) ◽  
pp. 3635-3642 ◽  
Author(s):  
Jaideep Behari ◽  
Philip Youngman
Keyword(s):  
Listeria Monocytogenes ◽  
Carbon Source ◽  
Virulence Genes ◽  
Carbon Sources ◽  
Virulence Gene ◽  
Anomalous Behavior ◽  
Negative Regulation ◽  
Wild Type ◽  
Glucosidase Activity ◽  
Strain Nctc

ABSTRACT Expression of the PrfA-controlled virulence gene hly(encoding the pore-forming cytolysin listeriolysin) is under negative regulation by readily metabolized carbon sources in Listeria monocytogenes. However, the hyperhemolytic strain NCTC 7973 exhibits deregulated hly expression in the presence of repressing sugars, raising the possibility that a defect in carbon source regulation is responsible for its anomalous behavior. We show here that the activity of a second glucose-repressed enzyme, α-glucosidase, is 10-fold higher in NCTC 7973 than in 10403S. Usinghly-gus fusions, we show that the prfA allele from NCTC 7973 causes deregulated hly-gus expression in the presence of sugars in either the wild-type or the NCTC 7973 background, while the 10403S prfA allele restores carbon source regulation. However, the prfA genotype does not affect the regulation of α-glucosidase activity by repressing sugars. Of the two mutational differences in PrfA, only a Gly145Ser change is important for regulation of hly-gus. Therefore, NCTC 7973 and 10403S have genetic differences in at least two loci: one in prfAthat affects carbon source regulation of virulence genes and another in an unidentified gene(s) that up-regulates α-glucosidase activity. We also show that the decrease in pH associated with utilization of sugars negatively regulates hly-gus expression, although sugars can affect hly-gus expression by another mechanism that is independent of pH.

scholarly journals Transport and Catabolism of Pentitols by Listeria monocytogenes

2016 ◽  
Vol 26 (6) ◽  
pp. 369-380 ◽  
Author(s):  
Takfarinas Kentache ◽  
Eliane Milohanic ◽  
Thanh Nguyen Cao ◽  
Abdelhamid Mokhtari ◽  
Francine Moussan Aké ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Virulence Genes ◽  
Virulence Gene ◽  
Pentose Phosphate ◽  
Phosphotransferase System ◽  
Virulence Gene Expression ◽  
Transposon Insertion ◽  
Encoding Gene ◽  
High Concentrations ◽  
Transcription Activators

Transposon insertion into <i>Listeria monocytogenes lmo2665</i>, which encodes an EIIC of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS), was found to prevent <smlcap>D</smlcap>-arabitol utilization. We confirm this result with a deletion mutant and show that Lmo2665 is also required for <smlcap>D</smlcap>-xylitol utilization. We therefore called this protein EIIC<sup>Axl</sup>. Both pentitols are probably catabolized via the pentose phosphate pathway (PPP) because <i>lmo2665</i> belongs to an operon, which encodes the three PTS<sup>Axl</sup> components, two sugar-P dehydrogenases, and most PPP enzymes. The two dehydrogenases oxidize the pentitol-phosphates produced during PTS-catalyzed transport to the PPP intermediate xylulose-5-P. <i>L. monocytogenes</i> contains another PTS, which exhibits significant sequence identity to PTS<sup>Axl</sup>. Its genes are also part of an operon encoding PPP enzymes. Deletion of the EIIC-encoding gene <i>(lmo0508)</i> affected neither <smlcap>D</smlcap>-arabitol nor <smlcap>D</smlcap>-xylitol utilization, although <smlcap>D</smlcap>-arabitol induces the expression of this operon. Both operons are controlled by MtlR/LicR-type transcription activators (Lmo2668 and Lmo0501, respectively). Phosphorylation of Lmo0501 by the soluble PTS<sup>Axl</sup> components probably explains why <smlcap>D</smlcap>-arabitol also induces the second pentitol operon. Listerial virulence genes are submitted to strong repression by PTS sugars, such as glucose. However, <smlcap>D</smlcap>-arabitol inhibited virulence gene expression only at high concentrations, probably owing to its less efficient utilization compared to glucose.

scholarly journals The bvr Locus of Listeria monocytogenes Mediates Virulence Gene Repression by β-Glucosides

1999 ◽  
Vol 181 (16) ◽  
pp. 5024-5032 ◽  
Author(s):  
Klaus Brehm ◽  
María-Teresa Ripio ◽  
Jürgen Kreft ◽  
José-Antonio Vázquez-Boland
Keyword(s):  
Listeria Monocytogenes ◽  
Virulence Genes ◽  
Natural Habitat ◽  
Sensory System ◽  
Virulence Gene ◽  
Gene Repression ◽  
Signal Molecules ◽  
Wild Type ◽  
Phosphotransferase System ◽  
Virulence Gene Expression

ABSTRACT The β-glucoside cellobiose has been reported to specifically repress the PrfA-dependent virulence genes hly andplcA in Listeria monocytogenes NCTC 7973. This led to the hypothesis that β-glucosides, sugars of plant origin, may act as signal molecules, preventing the expression of virulence genes if L. monocytogenes is living in its natural habitat (soil). In three other laboratory strains (EGD, L028, and 10403S), however, the effect of cellobiose was not unique, and all fermentable carbohydrates repressed hly. This suggested that the downregulation of virulence genes by β-glucosides is not a specific phenomenon but, rather, an aspect of a global regulatory mechanism of catabolite repression (CR). We assessed the effect of carbohydrates on virulence gene expression in a panel of wild-type isolates of L. monocytogenes by using the PrfA-dependent phospholipase C geneplcB as a reporter. Utilization of any fermentable sugar caused plcB repression in wild-type L. monocytogenes. However, an EGD variant was identified in which, as in NCTC 7973, plcB was only repressed by β-glucosides. Thus, the regulation of L. monocytogenes virulence genes by sugars appears to be mediated by two separate mechanisms, one presumably involving a CR pathway and another specifically responding to β-glucosides. We have identified in L. monocytogenes a 4-kb operon, bvrABC, encoding an antiterminator of the BglG family (bvrA), a β-glucoside-specific enzyme II permease component of the phosphoenolpyruvate-sugar phosphotransferase system (bvrB), and a putative ADP-ribosylglycohydrolase (bvrC). Low-stringency Southern blots showed that this locus is absent from other Listeria spp. Transcription ofbvrB was induced by cellobiose and salicin but not by arbutin. Disruption of the bvr operon by replacing part ofbvrAB with an interposon abolished the repression by cellobiose and salicin but not that by arbutin. Our data indicate that the bvr locus encodes a β-glucoside-specific sensor that mediates virulence gene repression upon detection of cellobiose and salicin. Bvr is the first sensory system found in L. monocytogenes that is involved in environmental regulation of virulence genes.

scholarly journals Carbon‐source regulation of virulence gene expression in Listeria monocytogenes

1997 ◽  
Vol 23 (5) ◽  
pp. 1075-1085 ◽  
Author(s):  
Andrea A. Milenbachs ◽  
David P. Brown ◽  
Marlena Moors ◽  
Philip Youngman
Keyword(s):  
Gene Expression ◽  
Listeria Monocytogenes ◽  
Carbon Source ◽  
Virulence Gene ◽  
Virulence Gene Expression

scholarly journals Influence of Sublethal Concentrations of Common Disinfectants on Expression of Virulence Genes in Listeria monocytogenes

2009 ◽  
Vol 76 (1) ◽  
pp. 303-309 ◽  
Author(s):  
Vicky G. Kastbjerg ◽  
Marianne Halberg Larsen ◽  
Lone Gram ◽  
Hanne Ingmer
Keyword(s):  
Gene Expression ◽  
Listeria Monocytogenes ◽  
Northern Blot ◽  
Food Industry ◽  
Virulence Genes ◽  
Virulence Gene ◽  
Human Pathogen ◽  
Active Components ◽  
Virulence Gene Expression ◽  
Sublethal Concentrations

ABSTRACT Listeria monocytogenes is a food-borne human pathogen that causes listeriosis, a relatively rare infection with a high fatality rate. The regulation of virulence gene expression is influenced by several environmental factors, and the aim of the present study was to determine how disinfectants used routinely in the food industry affect the expression of different virulence genes in L. monocytogenes when added at sublethal concentrations. An agar-based assay was developed to screen the effect of disinfectants on virulence gene promoter expression and was validated at the transcriptional level by Northern blot analysis. Eleven disinfectants representing four different groups of active components were evaluated in this study. Disinfectants with the same active ingredients had a similar effect on gene expression. Peroxy and chlorine compounds reduced the expression of the virulence genes, and quaternary ammonium compounds (QAC) induced the expression of the virulence genes. In general, a disinfectant had similar effects on the expression of all four virulence genes examined. Northern blot analyses confirmed the downregulation of prfA and inlA expression by Incimaxx DES (a peroxy compound) and their upregulation by Triquart Super (a QAC) in L. monocytogenes EGD. Hence, sublethal concentrations of disinfectants routinely used in the food industry affect virulence gene expression in the human pathogen L. monocytogenes, and the effect depends on the active components of the disinfectant. From a practical perspective, the study underlines that disinfectants should be used at the lethal concentrations recommended by the manufacturers. Further studies are needed to elucidate whether the changes in virulence gene expression induced by the disinfectants have impact on virulence or other biological properties, such as antibiotic resistance.

Tannin-Rich Pomegranate Rind Extracts Reduce Adhesion to and Invasion of Caco-2 Cells by Listeria monocytogenes and Decrease Its Expression of Virulence Genes

2015 ◽  
Vol 78 (1) ◽  
pp. 128-133 ◽  
Author(s):  
YUNFENG XU ◽  
GUANGHUI LI ◽  
BAIGANG ZHANG ◽  
QIAN WU ◽  
XIN WANG ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Epithelial Cells ◽  
Virulence Genes ◽  
Growth Curves ◽  
Virulence Gene ◽  
Antimicrobial Activities ◽  
Pcr Analysis ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Virulence Gene Expression

Pomegranate rind is rich in tannins that have remarkable antimicrobial activities. This study aimed to evaluate the effects of a tannin-rich fraction from pomegranate rind (TFPR) on Listeria monocytogenes virulence gene expression and on the pathogen's interaction with human epithelial cells. Growth curves were monitored to determine the effect of TFPR on L. monocytogenes growth. The 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide and fluorescence staining assays were used to examine the cytotoxicity of TFPR. The effects of TFPR on L. monocytogenes adhesion to and invasion of epithelial cells were investigated using Caco-2 cells. Real-time quantitative PCR analysis was conducted to quantify mRNA levels of three virulence genes in L. monocytogenes. Results showed that a MIC of TFPR against L. monocytogenes was 5 mg/ml in this study. TFPR exhibited cytotoxicity against Caco-2 cells when the concentration was 2.5 mg/ml. Subinhibitory concentrations of TFPR significantly reduced, in a dose-dependent manner, adhesion to and invasion of Caco-2 cells by L. monocytogenes. When L. monocytogenes was grown in the presence of 2.5 mg/ml TFPR, the transcriptional levels of prfA, inlA, and hly decreased by 17-, 34-, and 28-fold, respectively.

scholarly journals The Alternative Sigma Factor σB and the Virulence Gene Regulator PrfA Both Regulate Transcription of Listeria monocytogenes Internalins

2007 ◽  
Vol 73 (9) ◽  
pp. 2919-2930 ◽  
Author(s):  
Patrick McGann ◽  
Martin Wiedmann ◽  
Kathryn J. Boor
Keyword(s):  
Listeria Monocytogenes ◽  
Sigma Factor ◽  
Virulence Genes ◽  
Virulence Gene ◽  
Alternative Sigma Factor ◽  
Transcript Levels ◽  
Virulence Gene Expression ◽  
Reverse Transcription Pcr ◽  
Culture Cells ◽  
Tissue Culture Cells

ABSTRACT Some Listeria monocytogenes internalins are recognized as contributing to invasion of mammalian tissue culture cells. While PrfA is well established as a positive regulator of L. monocytogenes virulence gene expression, the stress-responsive σB has been recognized only recently as contributing to expression of virulence genes, including some that encode internalins. To measure the relative contributions of PrfA and σB to internalin gene transcription, we used reverse transcription-PCR to quantify transcript levels for eight internalin genes (inlA, inlB, inlC, inlC2, inlD, inlE, inlF, and inlG) in L. monocytogenes 10403S and in isogenic ΔprfA, ΔsigB, and ΔsigB ΔprfA strains. Strains were grown under defined conditions to produce (i) active PrfA, (ii) active σB and active PrfA, (iii) inactive PrfA, and (iv) active σB and inactive PrfA. Under the conditions tested, σB and PrfA contributed differentially to the expression of the various internalins such that (i) both σB and PrfA contributed to inlA and inlB transcription, (ii) only PrfA contributed to inlC transcription, (iii) only σB contributed to inlC2 and inlD transcription, and (iv) neither σB nor PrfA contributed to inlF and inlG transcription. inlE transcript levels were undetectable. The important role for σB in regulating expression of L. monocytogenes internalins suggests that exposure of this organism to environmental stress conditions, such as those encountered in the gastrointestinal tract, may activate internalin transcription. Interplay between σB and PrfA also appears to be critical for regulating transcription of some virulence genes, including inlA, inlB, and prfA.

scholarly journals Sequence Variations within PrfA DNA Binding Sites and Effects on Listeria monocytogenes Virulence Gene Expression

2000 ◽  
Vol 182 (3) ◽  
pp. 837-841 ◽  
Author(s):  
James R. Williams ◽  
Chetna Thayyullathil ◽  
Nancy E. Freitag
Keyword(s):  
Gene Expression ◽  
Listeria Monocytogenes ◽  
Dna Binding ◽  
Binding Sites ◽  
Virulence Genes ◽  
Regulation Of Gene Expression ◽  
Virulence Gene ◽  
Virulence Gene Expression ◽  
Dna Binding Sites ◽  
Sequence Variations

ABSTRACT Reporter gene fusions were used to investigate the contributions of PrfA DNA binding sites to Listeria monocytogenes virulence gene expression. Our results suggest that the DNA sequence of PrfA binding sites determines the levels of expression of certain virulence genes, such as hly and mpl. Other virulence genes, such as actA and plcB, may depend upon additional factors for full regulation of gene expression.

Vibrio harveyi virulence gene expression in vitro and in vivo during infection in black tiger shrimp Penaeus monodon

2020 ◽  
Vol 139 ◽  
pp. 153-160
Author(s):  
S Peeralil ◽  
TC Joseph ◽  
V Murugadas ◽  
PG Akhilnath ◽  
VN Sreejith ◽  
...  
Keyword(s):  
Gene Expression ◽  
Virulence Genes ◽  
Vibrio Harveyi ◽  
Penaeus Monodon ◽  
Challenge Test ◽  
Virulence Gene ◽  
Economic Losses ◽  
Virulence Gene Expression

Luminescent Vibrio harveyi is common in sea and estuarine waters. It produces several virulence factors and negatively affects larval penaeid shrimp in hatcheries, resulting in severe economic losses to shrimp aquaculture. Although V. harveyi is an important pathogen of shrimp, its pathogenicity mechanisms have yet to be completely elucidated. In the present study, isolates of V. harveyi were isolated and characterized from diseased Penaeus monodon postlarvae from hatcheries in Kerala, India, from September to December 2016. All 23 tested isolates were positive for lipase, phospholipase, caseinase, gelatinase and chitinase activity, and 3 of the isolates (MFB32, MFB71 and MFB68) showed potential for significant biofilm formation. Based on the presence of virulence genes, the isolates of V. harveyi were grouped into 6 genotypes, predominated by vhpA+ flaB+ ser+ vhh1- luxR+ vopD- vcrD+ vscN-. One isolate from each genotype was randomly selected for in vivo virulence experiments, and the LD50 ranged from 1.7 ± 0.5 × 103 to 4.1 ± 0.1 × 105 CFU ml-1. The expression of genes during the infection in postlarvae was high in 2 of the isolates (MFB12 and MFB32), consistent with the result of the challenge test. However, in MFB19, even though all genes tested were present, their expression level was very low and likely contributed to its lack of virulence. Because of the significant variation in gene expression, the presence of virulence genes alone cannot be used as a marker for pathogenicity of V. harveyi.

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