Dataset Information

N-dodecanoyl-homoserine lactone influences the levels of thiol and proteins related to oxidation-reduction process in Salmonella.

ABSTRACT: Quorum sensing is a cell-cell communication mechanism mediated by chemical signals that leads to differential gene expression in response to high population density. Salmonella is unable to synthesize the autoinducer-1 (AI-1), N-acyl homoserine lactone (AHL), but is able to recognize AHLs produced by other microorganisms through SdiA protein. This study aimed to evaluate the fatty acid and protein profiles of Salmonella enterica serovar Enteritidis PT4 578 throughout time of cultivation in the presence of AHL. The presence of N-dodecanoyl-homoserine lactone (C12-HSL) altered the fatty acid and protein profiles of Salmonella cultivated during 4, 6, 7, 12 and 36 h in anaerobic condition. The profiles of Salmonella Enteritidis at logarithmic phase of growth (4 h of cultivation), in the presence of C12-HSL, were similar to those of cells at late stationary phase (36 h). In addition, there was less variation in both protein and fatty acid profiles along growth, suggesting that this quorum sensing signal anticipated a stationary phase response. The presence of C12-HSL increased the abundance of thiol related proteins such as Tpx, Q7CR42, Q8ZP25, YfgD, AhpC, NfsB, YdhD and TrxA, as well as the levels of free cellular thiol after 6 h of cultivation, suggesting that these cells have greater potential to resist oxidative stress. Additionally, the LuxS protein which synthesizes the AI-2 signaling molecule was differentially abundant in the presence of C12-HSL. The NfsB protein had its abundance increased in the presence of C12-HSL at all evaluated times, which is a suggestion that the cells may be susceptible to the action of nitrofurans or that AHLs present some toxicity. Overall, the presence of C12-HSL altered important pathways related to oxidative stress and stationary phase response in Salmonella.

SUBMITTER: de Almeida FA

PROVIDER: S-EPMC6179229 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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N-dodecanoyl-homoserine lactone influences the levels of thiol and proteins related to oxidation-reduction process in Salmonella.

de Almeida Felipe Alves FA Carneiro Deisy Guimarães DG de Oliveira Mendes Tiago Antônio TA Barros Edvaldo E Pinto Uelinton Manoel UM de Oliveira Leandro Licursi LL Vanetti Maria Cristina Dantas MCD

PloS one 20181010 10

Quorum sensing is a cell-cell communication mechanism mediated by chemical signals that leads to differential gene expression in response to high population density. Salmonella is unable to synthesize the autoinducer-1 (AI-1), N-acyl homoserine lactone (AHL), but is able to recognize AHLs produced by other microorganisms through SdiA protein. This study aimed to evaluate the fatty acid and protein profiles of Salmonella enterica serovar Enteritidis PT4 578 throughout time of cultivation in the p ...[more]

PMID: 30304064

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Project description:Quorum sensing (QS) is a communication system in bacteria that regulates gene expression in response to a small diffusible signal indicative of the bacterial population present. QS has been shown to regulate virulence genes, biofilm formation, cell division and secretion systems in a diverse set of bacteria. Brucella melitensis produces a QS signaling molecule, N-dodecanoyl homoserine lactone (C12-HSL), that interacts with a LuxR transcriptional regulator, VjbR. Deletion of vjbR has been found to highly attenuate intracellular survival of B. melitensis. The importance of QS in the regulation of genes necessary for the establishment and maintenance of B. melitensis infection has already been described for the virB and fla operons, however, a complete description of the vjbR regulon has not been described. Genome mining revealed seven luxR-like genes in B. melitensis, only one of which, vjbR, was confirmed to be attenuated for intracellular survival using macrophage assays. Using custom B. melitensis microarrays, we compared transcripts from wild type and ∆vjbR strains in the presence and absence of exogenous C12-HSL. Comparison of the transcriptomes obtained from culture grown bacteria revealed bi-phasic gene regulation with expression peaks during exponential and early stationary growth phase; characterized by the regulation of 226 and 246 genes (respectively) by VjbR and 349 and 146 (respectively) altered by the addition of C12-HSL. Comparison of the VjbR and C12-HSL regulated genes provided confirmation that expression of 134 genes are regulated by both conditions with all but 3 genes inversely regulated. Overall, these results indicate that VjbR is an activator of gene expression at the exponential growth phase and exerts an equal effect on gene expression at the stationary growth phase; while C12-HSL has a repressive effect on gene expression at both growth stages examined and acts as an antagonist to VjbR activity. Direct transcript analysis comparing ∆vjbR with and without the addition of C12-HSL revealed that the AHL signal is able to direct gene expression in the absence of VjbR and exclusively exerted a positive influence on the expression of 56 genes, including a 93-fold increase in the expression of BabR, a second LuxR homologue. Genes regulated by these QS components included adhesins, proteases, antibiotic and toxin resistance genes, stress survival aids, including DNA repair genes and protein chaperones, transporters and porins, cellular membrane biogenesis genes, amino acid metabolism and transport, transcriptional regulators, and energy production genes. From these data, we conclude that QS is a global regulator of gene expression, and present potential virulence genes that may provide insight into the bacteria’s ability to establish and maintain the replicative vacuole (BCV) within the host cell. Keywords: Microarray comparison of a genetic deletion mutant and the addition of an effector molecule.

Project description:Quorum sensing (QS) is a communication system in bacteria that regulates gene expression in response to a small diffusible signal indicative of the bacterial population present. QS has been shown to regulate virulence genes, biofilm formation, cell division and secretion systems in a diverse set of bacteria. Brucella melitensis produces a QS signaling molecule, N-dodecanoyl homoserine lactone (C12-HSL), that interacts with a LuxR transcriptional regulator, VjbR. Deletion of vjbR has been found to highly attenuate intracellular survival of B. melitensis. The importance of QS in the regulation of genes necessary for the establishment and maintenance of B. melitensis infection has already been described for the virB and fla operons, however, a complete description of the vjbR regulon has not been described. Genome mining revealed seven luxR-like genes in B. melitensis, only one of which, vjbR, was confirmed to be attenuated for intracellular survival using macrophage assays. Using custom B. melitensis microarrays, we compared transcripts from wild type and ∆vjbR strains in the presence and absence of exogenous C12-HSL. Comparison of the transcriptomes obtained from culture-grown bacteria revealed bi-phasic gene regulation with expression peaks during exponential and early stationary growth phase; characterized by the regulation of 226 and 246 genes (respectively) by VjbR and 349 and 146 (respectively) altered by the addition of C12-HSL. Comparison of the VjbR and C12-HSL regulated genes provided confirmation that expression of 134 genes are regulated by both conditions with all but 3 genes inversely regulated. Overall, these results indicate that VjbR is an activator of gene expression at the exponential growth phase and exerts an equal effect on gene expression at the stationary growth phase; while C12-HSL has a repressive effect on gene expression at both growth stages examined and acts as an antagonist to VjbR activity. Direct transcript analysis comparing ∆vjbR with and without the addition of C12-HSL revealed that the AHL signal is able to direct gene expression in the absence of VjbR and exclusively exerted a positive influence on the expression of 56 genes, including a 93-fold increase in the expression of BabR, a second LuxR homologue. Genes regulated by these QS components included adhesins, proteases, antibiotic and toxin resistance genes, stress survival aids, including DNA repair genes and protein chaperones, transporters and porins, cellular membrane biogenesis genes, amino acid metabolism and transport, transcriptional regulators, and energy production genes. From these data, we conclude that QS is a global regulator of gene expression, and present potential virulence genes that may provide insight into the bacteria’s ability to establish and maintain the replicative vacuole (BCV) within the host cell. Keywords: Microarray comparison of a genetic deletion mutant and the addition of an effector molecule.

Project description:BackgroundQuorum sensing is a communication system that regulates gene expression in response to population density and often regulates virulence determinants. Deletion of the luxR homologue vjbR highly attenuates intracellular survival of Brucella melitensis and has been interpreted to be an indication of a role for QS in Brucella infection. Confirmation for such a role was suggested, but not confirmed, by the demonstrated in vitro synthesis of an auto-inducer (AI) by Brucella cultures. In an effort to further delineate the role of VjbR to virulence and survival, gene expression under the control of VjbR and AI was characterized using microarray analysis.ResultsAnalyses of wildtype B. melitensis and isogenic DeltavjbR transciptomes, grown in the presence and absence of exogenous N-dodecanoyl homoserine lactone (C12-HSL), revealed a temporal pattern of gene regulation with variances detected at exponential and stationary growth phases. Comparison of VjbR and C12-HSL transcriptomes indicated the shared regulation of 127 genes with all but 3 genes inversely regulated, suggesting that C12-HSL functions via VjbR in this case to reverse gene expression at these loci. Additional analysis using a DeltavjbR mutant revealed that AHL also altered gene expression in the absence of VjbR, up-regulating expression of 48 genes and a luxR homologue blxR 93-fold at stationary growth phase. Gene expression alterations include previously un-described adhesins, proteases, antibiotic and toxin resistance genes, stress survival aids, transporters, membrane biogenesis genes, amino acid metabolism and transport, transcriptional regulators, energy production genes, and the previously reported fliF and virB operons.ConclusionsVjbR and C12-HSL regulate expression of a large and diverse number of genes. Many genes identified as virulence factors in other bacterial pathogens were found to be differently expressed, suggesting an important contribution to intracellular survival of Brucella. From these data, we conclude that VjbR and C12-HSL contribute to virulence and survival by regulating expression of virulence mechanisms and thus controlling the ability of the bacteria to survive within the host cell. A likely scenario occurs via QS, however, operation of such a mechanism remains to be demonstrated.

Dataset Information

N-dodecanoyl-homoserine lactone influences the levels of thiol and proteins related to oxidation-reduction process in Salmonella.

Publications

N-dodecanoyl-homoserine lactone influences the levels of thiol and proteins related to oxidation-reduction process in Salmonella.

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