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Transcriptome signatures of class I and III stress response deregulation in Lactobacillus plantarum reveal pleiotropic adaptation.

Van Bokhorst-van de Veen H, Bongers RS, Wels M, Bron PA, Kleerebezem M - Microb. Cell Fact. (2013)

Bottom Line: Deletion of both regulators, elicited transcriptional changes of a large variety of additional genes in a temperature-dependent manner, including genes encoding functions involved in cell-envelope remodeling.Moreover, phenotypic assays revealed that both transcription regulators contribute to regulation of resistance to hydrogen peroxide stress.The integration of these results allowed the reconstruction of CtsR and HrcA regulatory networks in L. plantarum, highlighting the significant intertwinement of class I and III stress regulons.

View Article: PubMed Central - HTML - PubMed

Affiliation: TI Food & Nutrition, Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands. Michiel.Kleerebezem@nizo.com.

ABSTRACT

Background: To cope with environmental challenges bacteria possess sophisticated defense mechanisms that involve stress-induced adaptive responses. The canonical stress regulators CtsR and HrcA play a central role in the adaptations to a plethora of stresses in a variety of organisms. Here, we determined the CtsR and HrcA regulons of the lactic acid bacterium Lactobacillus plantarum WCFS1 grown under reference (28°C) and elevated (40°C) temperatures, using ctsR, hrcA, and ctsR-hrcA deletion mutants.

Results: While the maximum specific growth rates of the mutants and the parental strain were similar at both temperatures (0.33 ± 0.02 h(-1) and 0.34 ± 0.03 h(-1), respectively), DNA microarray analyses revealed that the CtsR or HrcA deficient strains displayed altered transcription patterns of genes encoding functions involved in transport and binding of sugars and other compounds, primary metabolism, transcription regulation, capsular polysaccharide biosynthesis, as well as fatty acid metabolism. These transcriptional signatures enabled the refinement of the gene repertoire that is directly or indirectly controlled by CtsR and HrcA of L. plantarum. Deletion of both regulators, elicited transcriptional changes of a large variety of additional genes in a temperature-dependent manner, including genes encoding functions involved in cell-envelope remodeling. Moreover, phenotypic assays revealed that both transcription regulators contribute to regulation of resistance to hydrogen peroxide stress. The integration of these results allowed the reconstruction of CtsR and HrcA regulatory networks in L. plantarum, highlighting the significant intertwinement of class I and III stress regulons.

Conclusions: Taken together, our results enabled the refinement of the CtsR and HrcA regulatory networks in L. plantarum, illustrating the complex nature of adaptive stress responses in this bacterium.

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Related in: MedlinePlus

Box plots displaying the absolute intensity of the first gene of the cps cluster 1 (lp_1177; A), the fab-operon (lp_1670; B), dak1A (lp_0166; C), cfa2 (lp_3174; D), and lp_0988 (E) of L. plantarum WCFS1 (wild type), NZ3410 (ΔctsR), NZ3425CM (ΔhrcA), and NZ3423CM (ΔctsRΔhrcA) grown at 28°C or 40°C. Asterisk indicates that (part) of the loci are significant differentially expressed when compared to the strains growth at the other temperature.
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Figure 5: Box plots displaying the absolute intensity of the first gene of the cps cluster 1 (lp_1177; A), the fab-operon (lp_1670; B), dak1A (lp_0166; C), cfa2 (lp_3174; D), and lp_0988 (E) of L. plantarum WCFS1 (wild type), NZ3410 (ΔctsR), NZ3425CM (ΔhrcA), and NZ3423CM (ΔctsRΔhrcA) grown at 28°C or 40°C. Asterisk indicates that (part) of the loci are significant differentially expressed when compared to the strains growth at the other temperature.

Mentions: In addition, the mutations of hrcA and/or ctsR appeared to play a role in the control of expression of some of the genes and functions that were affected by the temperature of growth in the wild-type strain (see above). Temperature-mediated regulation appeared to be (partially) lost in the ΔctsR mutant (cps1), in the ΔhrcA::cat mutant (fab operon, dak1A, and cfa2), or in the ΔctsRΔhrcA::cat mutant [lp_0988 (lipoprotein precursor), cps1, and cfa2] compared to that seen in the wild-type strain (Figure 5). This indicates that inactivation of both class I and III transcription regulation leads to deregulation of different combinations of cell envelope biosynthesis processes compared to deregulation of one of the regulators in a temperature-dependent way. Taken together, these findings indicate that some of the more prominent adaptations that the wild-type strain employs to combat elevated growth temperatures, appear to be deregulated in the HrcA and CtsR mutant strains.


Transcriptome signatures of class I and III stress response deregulation in Lactobacillus plantarum reveal pleiotropic adaptation.

Van Bokhorst-van de Veen H, Bongers RS, Wels M, Bron PA, Kleerebezem M - Microb. Cell Fact. (2013)

Box plots displaying the absolute intensity of the first gene of the cps cluster 1 (lp_1177; A), the fab-operon (lp_1670; B), dak1A (lp_0166; C), cfa2 (lp_3174; D), and lp_0988 (E) of L. plantarum WCFS1 (wild type), NZ3410 (ΔctsR), NZ3425CM (ΔhrcA), and NZ3423CM (ΔctsRΔhrcA) grown at 28°C or 40°C. Asterisk indicates that (part) of the loci are significant differentially expressed when compared to the strains growth at the other temperature.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3842655&req=5

Figure 5: Box plots displaying the absolute intensity of the first gene of the cps cluster 1 (lp_1177; A), the fab-operon (lp_1670; B), dak1A (lp_0166; C), cfa2 (lp_3174; D), and lp_0988 (E) of L. plantarum WCFS1 (wild type), NZ3410 (ΔctsR), NZ3425CM (ΔhrcA), and NZ3423CM (ΔctsRΔhrcA) grown at 28°C or 40°C. Asterisk indicates that (part) of the loci are significant differentially expressed when compared to the strains growth at the other temperature.
Mentions: In addition, the mutations of hrcA and/or ctsR appeared to play a role in the control of expression of some of the genes and functions that were affected by the temperature of growth in the wild-type strain (see above). Temperature-mediated regulation appeared to be (partially) lost in the ΔctsR mutant (cps1), in the ΔhrcA::cat mutant (fab operon, dak1A, and cfa2), or in the ΔctsRΔhrcA::cat mutant [lp_0988 (lipoprotein precursor), cps1, and cfa2] compared to that seen in the wild-type strain (Figure 5). This indicates that inactivation of both class I and III transcription regulation leads to deregulation of different combinations of cell envelope biosynthesis processes compared to deregulation of one of the regulators in a temperature-dependent way. Taken together, these findings indicate that some of the more prominent adaptations that the wild-type strain employs to combat elevated growth temperatures, appear to be deregulated in the HrcA and CtsR mutant strains.

Bottom Line: Deletion of both regulators, elicited transcriptional changes of a large variety of additional genes in a temperature-dependent manner, including genes encoding functions involved in cell-envelope remodeling.Moreover, phenotypic assays revealed that both transcription regulators contribute to regulation of resistance to hydrogen peroxide stress.The integration of these results allowed the reconstruction of CtsR and HrcA regulatory networks in L. plantarum, highlighting the significant intertwinement of class I and III stress regulons.

View Article: PubMed Central - HTML - PubMed

Affiliation: TI Food & Nutrition, Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands. Michiel.Kleerebezem@nizo.com.

ABSTRACT

Background: To cope with environmental challenges bacteria possess sophisticated defense mechanisms that involve stress-induced adaptive responses. The canonical stress regulators CtsR and HrcA play a central role in the adaptations to a plethora of stresses in a variety of organisms. Here, we determined the CtsR and HrcA regulons of the lactic acid bacterium Lactobacillus plantarum WCFS1 grown under reference (28°C) and elevated (40°C) temperatures, using ctsR, hrcA, and ctsR-hrcA deletion mutants.

Results: While the maximum specific growth rates of the mutants and the parental strain were similar at both temperatures (0.33 ± 0.02 h(-1) and 0.34 ± 0.03 h(-1), respectively), DNA microarray analyses revealed that the CtsR or HrcA deficient strains displayed altered transcription patterns of genes encoding functions involved in transport and binding of sugars and other compounds, primary metabolism, transcription regulation, capsular polysaccharide biosynthesis, as well as fatty acid metabolism. These transcriptional signatures enabled the refinement of the gene repertoire that is directly or indirectly controlled by CtsR and HrcA of L. plantarum. Deletion of both regulators, elicited transcriptional changes of a large variety of additional genes in a temperature-dependent manner, including genes encoding functions involved in cell-envelope remodeling. Moreover, phenotypic assays revealed that both transcription regulators contribute to regulation of resistance to hydrogen peroxide stress. The integration of these results allowed the reconstruction of CtsR and HrcA regulatory networks in L. plantarum, highlighting the significant intertwinement of class I and III stress regulons.

Conclusions: Taken together, our results enabled the refinement of the CtsR and HrcA regulatory networks in L. plantarum, illustrating the complex nature of adaptive stress responses in this bacterium.

Show MeSH
Related in: MedlinePlus