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Identification and characterization of the chromosomal yefM-yoeB toxin-antitoxin system of Streptococcus suis.

Zheng C, Xu J, Ren S, Li J, Xia M, Chen H, Bei W - Sci Rep (2015)

Bottom Line: Overproduction of S. suis YoeB toxin inhibited the growth of E. coli, and the toxicity of S. suis YoeB could be alleviated by the antitoxin YefM from S. suis and Streptococcus pneumoniae, but not by E. coli YefM.In a murine infection model, deletion of the yefM-yoeB locus had no effect on the virulence of S. suis serotype 2.Collectively, our data suggested that the yefM-yoeB locus of S. suis is an active TA system without the involvement of virulence.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China [2] Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.

ABSTRACT
Toxin-antitoxin (TA) systems are widely prevalent in the genomes of bacteria and archaea. These modules have been identified in Escherichia coli and various other bacteria. However, their presence in the genome of Streptococcus suis, an important zoonotic pathogen, has received little attention. In this study, we describe the identification and characterization of a type II TA system, comprising the chromosomal yefM-yoeB locus of S. suis. The yefM-yoeB locus is present in the genome of most serotypes of S. suis. Overproduction of S. suis YoeB toxin inhibited the growth of E. coli, and the toxicity of S. suis YoeB could be alleviated by the antitoxin YefM from S. suis and Streptococcus pneumoniae, but not by E. coli YefM. More importantly, introduction of the S. suis yefM-yoeB system into E. coli could affect cell growth. In a murine infection model, deletion of the yefM-yoeB locus had no effect on the virulence of S. suis serotype 2. Collectively, our data suggested that the yefM-yoeB locus of S. suis is an active TA system without the involvement of virulence.

No MeSH data available.


Related in: MedlinePlus

No apparent role of the yefM-yoeB locus in the virulence of S. suis 2.(a) Survival curves of mice infected with the WT, ΔyefM-yoeB and CΔyefM-yoeB strains. Groups of ten female CD1 mice were inoculated intraperitoneally with the WT, ΔyefM-yoeB and CΔyefM-yoeB strains at a dose of 6 × 108 CFU. Mice inoculated with PBS served as the control. Survival data were analysed with the log-rank test. No significant difference was observed between the ΔyefM-yoeB group and the WT group or the CΔyefM-yoeB group. (b) Competitive index of ΔyefM-yoeB against the WT strain. Four female CD1 mice were inoculated intraperitoneally with a mixture of ΔyefM-yoeB and WT at a ratio of 1:1. At 24 h post-infection, blood, brain, heart, liver, spleen, lung and kidney samples from the mice were collected and plated. The ΔyefM-yoeB:WT ratio in these samples was determined by analysing 70–90 colonies by colony PCR. The competitive index (CI) was determined as the mutant:WT ratio in the samples divided by the ratio in the inoculum. A CI value of 1 indicates equal competitiveness. Mean CI values from four mice were compared to 1 using the two-tailed paired t test to determine whether the difference in competitiveness was significant. No statistically significant difference was found.
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f8: No apparent role of the yefM-yoeB locus in the virulence of S. suis 2.(a) Survival curves of mice infected with the WT, ΔyefM-yoeB and CΔyefM-yoeB strains. Groups of ten female CD1 mice were inoculated intraperitoneally with the WT, ΔyefM-yoeB and CΔyefM-yoeB strains at a dose of 6 × 108 CFU. Mice inoculated with PBS served as the control. Survival data were analysed with the log-rank test. No significant difference was observed between the ΔyefM-yoeB group and the WT group or the CΔyefM-yoeB group. (b) Competitive index of ΔyefM-yoeB against the WT strain. Four female CD1 mice were inoculated intraperitoneally with a mixture of ΔyefM-yoeB and WT at a ratio of 1:1. At 24 h post-infection, blood, brain, heart, liver, spleen, lung and kidney samples from the mice were collected and plated. The ΔyefM-yoeB:WT ratio in these samples was determined by analysing 70–90 colonies by colony PCR. The competitive index (CI) was determined as the mutant:WT ratio in the samples divided by the ratio in the inoculum. A CI value of 1 indicates equal competitiveness. Mean CI values from four mice were compared to 1 using the two-tailed paired t test to determine whether the difference in competitiveness was significant. No statistically significant difference was found.

Mentions: To assess the role of the yefM-yoeB locus in the pathogenesis of S. suis 2, we performed an experimental infection model in CD1 mice. As an initial comparison of virulence, groups of ten CD1 mice were inoculated intraperitoneally with 6 × 108 CFU of the WT, ΔyefM-yoeB, CΔyefM-yoeB strains or PBS. Most mice infected with S. suis strains developed typical clinical signs of S. suis 2 infection, including depression, lethargy, weakness, prostration and rough coat hair during the first 72 h post infection. Ultimately, the survival rates of mice in the WT, ΔyefM-yoeB and CΔyefM-yoeB groups were 50%, 60% and 30%, respectively (Fig. 8a). By contrast, all mice inoculated with PBS remained healthy and survived. No significant difference in survival rates was observed between the ΔyefM-yoeB group and the WT group (P = 0.6793), or the C∆yefM-yoeB group (P = 0.1924). Thus, it seemed likely that the yefM-yoeB locus has no role in S. suis 2 virulence.


Identification and characterization of the chromosomal yefM-yoeB toxin-antitoxin system of Streptococcus suis.

Zheng C, Xu J, Ren S, Li J, Xia M, Chen H, Bei W - Sci Rep (2015)

No apparent role of the yefM-yoeB locus in the virulence of S. suis 2.(a) Survival curves of mice infected with the WT, ΔyefM-yoeB and CΔyefM-yoeB strains. Groups of ten female CD1 mice were inoculated intraperitoneally with the WT, ΔyefM-yoeB and CΔyefM-yoeB strains at a dose of 6 × 108 CFU. Mice inoculated with PBS served as the control. Survival data were analysed with the log-rank test. No significant difference was observed between the ΔyefM-yoeB group and the WT group or the CΔyefM-yoeB group. (b) Competitive index of ΔyefM-yoeB against the WT strain. Four female CD1 mice were inoculated intraperitoneally with a mixture of ΔyefM-yoeB and WT at a ratio of 1:1. At 24 h post-infection, blood, brain, heart, liver, spleen, lung and kidney samples from the mice were collected and plated. The ΔyefM-yoeB:WT ratio in these samples was determined by analysing 70–90 colonies by colony PCR. The competitive index (CI) was determined as the mutant:WT ratio in the samples divided by the ratio in the inoculum. A CI value of 1 indicates equal competitiveness. Mean CI values from four mice were compared to 1 using the two-tailed paired t test to determine whether the difference in competitiveness was significant. No statistically significant difference was found.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4536659&req=5

f8: No apparent role of the yefM-yoeB locus in the virulence of S. suis 2.(a) Survival curves of mice infected with the WT, ΔyefM-yoeB and CΔyefM-yoeB strains. Groups of ten female CD1 mice were inoculated intraperitoneally with the WT, ΔyefM-yoeB and CΔyefM-yoeB strains at a dose of 6 × 108 CFU. Mice inoculated with PBS served as the control. Survival data were analysed with the log-rank test. No significant difference was observed between the ΔyefM-yoeB group and the WT group or the CΔyefM-yoeB group. (b) Competitive index of ΔyefM-yoeB against the WT strain. Four female CD1 mice were inoculated intraperitoneally with a mixture of ΔyefM-yoeB and WT at a ratio of 1:1. At 24 h post-infection, blood, brain, heart, liver, spleen, lung and kidney samples from the mice were collected and plated. The ΔyefM-yoeB:WT ratio in these samples was determined by analysing 70–90 colonies by colony PCR. The competitive index (CI) was determined as the mutant:WT ratio in the samples divided by the ratio in the inoculum. A CI value of 1 indicates equal competitiveness. Mean CI values from four mice were compared to 1 using the two-tailed paired t test to determine whether the difference in competitiveness was significant. No statistically significant difference was found.
Mentions: To assess the role of the yefM-yoeB locus in the pathogenesis of S. suis 2, we performed an experimental infection model in CD1 mice. As an initial comparison of virulence, groups of ten CD1 mice were inoculated intraperitoneally with 6 × 108 CFU of the WT, ΔyefM-yoeB, CΔyefM-yoeB strains or PBS. Most mice infected with S. suis strains developed typical clinical signs of S. suis 2 infection, including depression, lethargy, weakness, prostration and rough coat hair during the first 72 h post infection. Ultimately, the survival rates of mice in the WT, ΔyefM-yoeB and CΔyefM-yoeB groups were 50%, 60% and 30%, respectively (Fig. 8a). By contrast, all mice inoculated with PBS remained healthy and survived. No significant difference in survival rates was observed between the ΔyefM-yoeB group and the WT group (P = 0.6793), or the C∆yefM-yoeB group (P = 0.1924). Thus, it seemed likely that the yefM-yoeB locus has no role in S. suis 2 virulence.

Bottom Line: Overproduction of S. suis YoeB toxin inhibited the growth of E. coli, and the toxicity of S. suis YoeB could be alleviated by the antitoxin YefM from S. suis and Streptococcus pneumoniae, but not by E. coli YefM.In a murine infection model, deletion of the yefM-yoeB locus had no effect on the virulence of S. suis serotype 2.Collectively, our data suggested that the yefM-yoeB locus of S. suis is an active TA system without the involvement of virulence.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, 430070, China [2] Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.

ABSTRACT
Toxin-antitoxin (TA) systems are widely prevalent in the genomes of bacteria and archaea. These modules have been identified in Escherichia coli and various other bacteria. However, their presence in the genome of Streptococcus suis, an important zoonotic pathogen, has received little attention. In this study, we describe the identification and characterization of a type II TA system, comprising the chromosomal yefM-yoeB locus of S. suis. The yefM-yoeB locus is present in the genome of most serotypes of S. suis. Overproduction of S. suis YoeB toxin inhibited the growth of E. coli, and the toxicity of S. suis YoeB could be alleviated by the antitoxin YefM from S. suis and Streptococcus pneumoniae, but not by E. coli YefM. More importantly, introduction of the S. suis yefM-yoeB system into E. coli could affect cell growth. In a murine infection model, deletion of the yefM-yoeB locus had no effect on the virulence of S. suis serotype 2. Collectively, our data suggested that the yefM-yoeB locus of S. suis is an active TA system without the involvement of virulence.

No MeSH data available.


Related in: MedlinePlus