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Glycerol metabolism and PrfA activity in Listeria monocytogenes.

ABSTRACT: Listeria monocytogenes is able to efficiently utilize glycerol as a carbon source. In a defined minimal medium, the growth rate (during balanced growth) in the presence of glycerol is similar to that in the presence of glucose or cellobiose. Comparative transcriptome analyses of L. monocytogenes showed high-level transcriptional upregulation of the genes known to be involved in glycerol uptake and metabolism (glpFK and glpD) in the presence of glycerol (compared to that in the presence of glucose and/or cellobiose). Levels of expression of the genes encoding a second putative glycerol uptake facilitator (GlpF(2)) and a second putative glycerol kinase (GlpK(2)) were less enhanced under these conditions. GlpK(1) but not GlpK(2) was essential for glycerol catabolism in L. monocytogenes under extracellular conditions, while the loss of GlpK(1) affected replication in Caco-2 cells less than did the loss of GlpK(2) and GlpD. Additional genes whose transcription levels were higher in the presence of glycerol than in the presence of glucose and cellobiose included those for two dihydroxyacetone (Dha) kinases and many genes that are under carbon catabolite repression control. Transcriptional downregulation in the presence of glycerol (compared to those in the presence glucose and cellobiose) was observed for several genes and operons that are positively regulated by glucose, including genes involved in glycolysis, N metabolism, and the biosynthesis of branched-chain amino acids. The highest level of transcriptional upregulation was observed for all PrfA-dependent genes during early and late logarithmic growth in glycerol. Under these conditions, a low level of HPr-Ser-P and a high level of HPr-His-P were present in the cells, suggesting that all enzyme IIA (EIIA) (or EIIB) components of the phosphotransferase system (PTS) permeases expressed will be phosphorylated. These and other data suggest that the phosphorylation state of PTS permeases correlates with PrfA activity.

SUBMITTER: Joseph B

PROVIDER: S-EPMC2493282 | biostudies-literature | 2008 Aug

REPOSITORIES: biostudies-literature

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Glycerol metabolism and PrfA activity in Listeria monocytogenes.

Joseph Biju B Mertins Sonja S Stoll Regina R Schär Jennifer J Umesha Kanasinakatte Rudrappa KR Luo Qin Q Müller-Altrock Stefanie S Goebel Werner W

Journal of bacteriology 20080523 15

Listeria monocytogenes is able to efficiently utilize glycerol as a carbon source. In a defined minimal medium, the growth rate (during balanced growth) in the presence of glycerol is similar to that in the presence of glucose or cellobiose. Comparative transcriptome analyses of L. monocytogenes showed high-level transcriptional upregulation of the genes known to be involved in glycerol uptake and metabolism (glpFK and glpD) in the presence of glycerol (compared to that in the presence of glucos ...[more]

PMID: 18502850

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Project description:Listeria monocytogenes is able to efficiently utilize glycerol as carbon source. In a defined minimal medium the growth rate is similar (during balanced growth) in presence of glycerol as in presence of glucose or cellobiose. Comparative transcriptome analyses of L. monocytogenes showed in the presence of glycerol (compared to glucose and/or cellobiose) high transcriptional upregulation of the known genes involved in glycerol uptake and metabolism (glpFK, glpD). Expression of the genes encoding a second putative glycerol uptake facilitator (GlpF-2) and a second putative glycerol kinase (GlpK-2) was less enhanced under these conditions. GlpK-1 but not GlpK-2 was essential for glycerol catabolism in L. monocytogenes under extracellular conditions, while loss of GlpK-1 affected replication in Caco-2 cells less than loss of GlpK-2 and GlpD. Additional genes whose transcription was higher in presence of glycerol than in presence of glucose and cellobiose included those for two dihydroxyacetone (Dha) kinases and many genes that are under carbon catabolite repression (CCR) control. Transcriptional down-regulation in the presence of glycerol (compared to glucose and cellobiose) was observed for several genes and operons that are positively regulated by glucose, including genes involved in glycolysis, N-metabolism and biosynthesis of branched chain amino acids. The highest transcriptional up-regulation was observed for all PrfA-dependent genes during early and late logarithmic growth in glycerol. Under these conditions a low level of HPr-Ser-P and a high level of HPr-His-P was present in the cells, suggesting that all EIIA (B) components of the PTS permeases expressed will be phosphorylated. These and other data reported suggest that the phosphorylation state of PTS permeases correlates with PrfA activity. Keywords: Response of Listeria monocytogenes to different carbon sources A total of four independently isolated RNA samples from each condition at each growth phase were used for the analysis. RNA from two isolations were pooled and hybridized onto two microarray slides with dye swap. Another two microarray slides were hybridized using the same principle. In total, we used four RNAs and four microarray slides to generate 16 replicate expression values for each combination except for the comparison between glucose and cellobiose, phase B where data generated from three microarray slides were used for further analysis

Project description:PrfA activity was studied in L. monocytogenes strain EGD and in an isogenic prfA deletion mutant (EGDΔprfA) carrying multiple copies of the wild-type prfA or the mutant prfA* gene (strains EGDΔprfApPrfA and EGDΔprfApPrfA*) after growth in brain heart infusion (BHI), Luria-Bertani broth (LB) or a defined minimal medium (MM) supplemented either with one of the three PTS-carbohydrates, glucose, mannose and cellobiose, or the non-PTS carbon source glycerol. Low PrfA activity was observed in the wild-type EGD strain in BHI and LB with either of these carbon sources, while PrfA activity was high in minimal medium in presence of glycerol but significantly reduced in presence of cellobiose. The strains expressing the prfA and prfA* gene under the prfA promoters, P1 and P2, produced equally large amounts of PrfA protein and high PrfA activity was observed in strain EGDΔprfApPrfA* under all growth conditions. In contrast, high PrfA activity in strain EGDΔprfApPrfA was only observed when this strain was cultured in BHI but not in LB or MM (in presence of either carbon source). A ptsH mutant (lacking a functional HPr) was able to grow in BHI suggesting that growth of L. monocytogenes in this culture medium is supported by carbon sources whose uptake and metabolism are independent of the PTS pathway. However, this mutant was unable to grow in LB and MM regardless which of the four carbon sources was added, suggesting that uptake of the used carbohydrates and the catabolism of glycerol depend fully on the functional common PTS pathway. Furthermore, the growth rates of L. monocytogenes are strongly reduced in presence of large amounts of PrfA protein when growing MM but less in LB and only slightly in BHI. The expression profiles of the genes encoding PTS permeases were determined in the three strains under various growth conditions. The data suggest that PrfA activity correlates with the expression level and the phosphorylation state of specific PTS permeases. This SuperSeries is composed of the SubSeries listed below.

Project description:Naturally occurring free fatty acids (FFAs) are recognized as potent antimicrobial agents that also affect the production of virulence factors in bacterial pathogens. In the foodborne pathogen Listeria monocytogenes, some medium- and long-chain FFAs act as antimicrobial agents as well as signaling compounds, causing a repression of transcription of virulence genes. We previously observed that the master virulence regulator PrfA is involved in both the antimicrobial and virulence-inhibitory response of L. monocytogenes to selected FFAs, but the underlying mechanisms are presently unknown. Here, we present a systematic analysis of the antimicrobial and PrfA-inhibitory activities of medium- and long-chain FFAs of various carbon chain lengths and degrees of saturation. We observed that exposure to specific antimicrobial and nonantimicrobial FFAs prevented PrfA-dependent activation of virulence gene transcription and reduced the levels of PrfA-regulated virulence factors. Thus, an antimicrobial activity was not compulsory for the PrfA-inhibitory ability of an FFA. In vitro binding experiments revealed that PrfA-inhibitory FFAs were also able to prevent the constitutively active variant PrfA* from binding to the PrfA box in the promoter region of the virulence gene hly, whereas noninhibitory FFAs did not affect its ability to bind DNA. Notably, the unsaturated FFAs inhibited the DNA binding activity of PrfA* most efficiently. Altogether, our findings support a model in which specific FFAs orchestrate a generalized reduction of the virulence potential of L. monocytogenes by directly targeting the key virulence regulator PrfA.IMPORTANCE Listeria monocytogenes is a Gram-positive pathogen able to cause foodborne infections in humans and animals. Key virulence genes in L. monocytogenes are activated by the transcription regulator PrfA, a DNA binding protein belonging to the CRP/FNR family. Various signals from the environment are known to affect the activity of PrfA, either positively or negatively. Recently, we found that specific medium- and long-chain free fatty acids act as antimicrobial agents as well as signaling compounds in L. monocytogenes Here, we show that both antimicrobial and nonantimicrobial free fatty acids inhibit PrfA-dependent activation of virulence gene transcription by interfering with the DNA binding activity of PrfA. Our findings suggest that free fatty acids could be candidates for alternative therapies against L. monocytogenes.

Dataset Information

Glycerol metabolism and PrfA activity in Listeria monocytogenes.

Publications

Glycerol metabolism and PrfA activity in Listeria monocytogenes.

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