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A functional peptidoglycan hydrolase characterized from T4SS in 89K pathogenicity island of epidemic Streptococcus suis serotype 2.

Zhong Q, Zhao Y, Chen T, Yin S, Yao X, Wang J, Lu S, Tan Y, Tang J, Zheng B, Hu F, Li M - BMC Microbiol. (2014)

Bottom Line: In the current study, the CHAP domain of VirB1-89K from S. suis 89K PAI was cloned and over-expressed in Escherichia coli, and its peptidoglycan-degrading activity in vitro was determined.Deletion of virB1-89K reduces significantly, but does not abolish, the virulence of S. suis in a mouse model.The experimental results presented here suggested that VirB1-89K facilitates the assembly of 89K T4SS apparatus by catalyzing the degradation of the peptidoglycan cell wall, thus contributing to the pathogenesis of S. suis 2 infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, Third Military Medical University, Chongqing 400038, China. hufuquan2009@aliyun.com.

ABSTRACT

Background: Streptococcus suis serotype 2 (S. suis 2) has evolved efficient mechanisms to cause streptococcal toxic shock syndrome (STSS), which is a new emerging infectious disease linked to S. suis. We have previously reported that a type IV secretion system (T4SS) harbored by the specific 89K pathogenicity island (PAI) of S. suis 2 contributes to the development of STSS and mediates horizontal transfer of 89K. However, the 89K T4SS machinery assembly in vivo and in vitro is poorly understood, and the component acting directly to digest the bacterial cell wall needs to be identified.

Results: The virB1-89K gene product encoded in the 89K PAI is the only one that shows similarity to the Agrobacterium VirB1 component and contains a conserved CHAP domain that may function in peptidoglycan hydrolysis, which makes it a plausible candidate acting as a hydrolase against the peptidoglycan cell wall to allow the assembly of the T4SS apparatus. In the current study, the CHAP domain of VirB1-89K from S. suis 89K PAI was cloned and over-expressed in Escherichia coli, and its peptidoglycan-degrading activity in vitro was determined. The results indicated that the VirB1-89K CHAP domain can degrade the peptidoglycan layer of bacteria. Deletion of virB1-89K reduces significantly, but does not abolish, the virulence of S. suis in a mouse model.

Conclusions: The experimental results presented here suggested that VirB1-89K facilitates the assembly of 89K T4SS apparatus by catalyzing the degradation of the peptidoglycan cell wall, thus contributing to the pathogenesis of S. suis 2 infection.

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Dynamic changes in lytic activity of VirB1-89KCHAP at different pH values or temperatures. (A) The effect of pH on enzyme activity of VirB1-89KCHAP. (B) The effect of temperature on enzyme activity of VirB1-89KCHAP. (C) Thermostability of the VirB1-89KCHAP protein. Results shown are representative of three independent experiments.
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Figure 4: Dynamic changes in lytic activity of VirB1-89KCHAP at different pH values or temperatures. (A) The effect of pH on enzyme activity of VirB1-89KCHAP. (B) The effect of temperature on enzyme activity of VirB1-89KCHAP. (C) Thermostability of the VirB1-89KCHAP protein. Results shown are representative of three independent experiments.

Mentions: To reveal the basic biological characteristics of VirB1-89KCHAP, we examined the optimum reaction condition of VirB1-89KCHAP by using Micrococcus lysodeikticus cells as substrate. Results showed that on increasing the pH, peptidoglycan hydrolase activity of VirB1-89KCHAP increases and reaches maximum at pH 8.0 (Figure 4A). When the pH exceeds 9.0, the relative activity decreased sharply. VirB1-89KCHAP functions best at an optimal temperature of 40°C. The enzyme activity rapidly declined at temperatures above 50°C and only 25% of the maximal activity was measured at 60°C (Figure 4B). From the thermal stability data, the relative activity is higher at 30°C than at 40°C, suggesting that pre-incubation of VirB1-89KCHAP at 30°C causes lower decay in relative activity compared to the enzyme pre-incubated at 40°C (Figure 4C). With increasing temperature, pre-incubation of VirB1-89KCHAP caused increasing decay in the relative activity of the enzyme.


A functional peptidoglycan hydrolase characterized from T4SS in 89K pathogenicity island of epidemic Streptococcus suis serotype 2.

Zhong Q, Zhao Y, Chen T, Yin S, Yao X, Wang J, Lu S, Tan Y, Tang J, Zheng B, Hu F, Li M - BMC Microbiol. (2014)

Dynamic changes in lytic activity of VirB1-89KCHAP at different pH values or temperatures. (A) The effect of pH on enzyme activity of VirB1-89KCHAP. (B) The effect of temperature on enzyme activity of VirB1-89KCHAP. (C) Thermostability of the VirB1-89KCHAP protein. Results shown are representative of three independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3974602&req=5

Figure 4: Dynamic changes in lytic activity of VirB1-89KCHAP at different pH values or temperatures. (A) The effect of pH on enzyme activity of VirB1-89KCHAP. (B) The effect of temperature on enzyme activity of VirB1-89KCHAP. (C) Thermostability of the VirB1-89KCHAP protein. Results shown are representative of three independent experiments.
Mentions: To reveal the basic biological characteristics of VirB1-89KCHAP, we examined the optimum reaction condition of VirB1-89KCHAP by using Micrococcus lysodeikticus cells as substrate. Results showed that on increasing the pH, peptidoglycan hydrolase activity of VirB1-89KCHAP increases and reaches maximum at pH 8.0 (Figure 4A). When the pH exceeds 9.0, the relative activity decreased sharply. VirB1-89KCHAP functions best at an optimal temperature of 40°C. The enzyme activity rapidly declined at temperatures above 50°C and only 25% of the maximal activity was measured at 60°C (Figure 4B). From the thermal stability data, the relative activity is higher at 30°C than at 40°C, suggesting that pre-incubation of VirB1-89KCHAP at 30°C causes lower decay in relative activity compared to the enzyme pre-incubated at 40°C (Figure 4C). With increasing temperature, pre-incubation of VirB1-89KCHAP caused increasing decay in the relative activity of the enzyme.

Bottom Line: In the current study, the CHAP domain of VirB1-89K from S. suis 89K PAI was cloned and over-expressed in Escherichia coli, and its peptidoglycan-degrading activity in vitro was determined.Deletion of virB1-89K reduces significantly, but does not abolish, the virulence of S. suis in a mouse model.The experimental results presented here suggested that VirB1-89K facilitates the assembly of 89K T4SS apparatus by catalyzing the degradation of the peptidoglycan cell wall, thus contributing to the pathogenesis of S. suis 2 infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, Third Military Medical University, Chongqing 400038, China. hufuquan2009@aliyun.com.

ABSTRACT

Background: Streptococcus suis serotype 2 (S. suis 2) has evolved efficient mechanisms to cause streptococcal toxic shock syndrome (STSS), which is a new emerging infectious disease linked to S. suis. We have previously reported that a type IV secretion system (T4SS) harbored by the specific 89K pathogenicity island (PAI) of S. suis 2 contributes to the development of STSS and mediates horizontal transfer of 89K. However, the 89K T4SS machinery assembly in vivo and in vitro is poorly understood, and the component acting directly to digest the bacterial cell wall needs to be identified.

Results: The virB1-89K gene product encoded in the 89K PAI is the only one that shows similarity to the Agrobacterium VirB1 component and contains a conserved CHAP domain that may function in peptidoglycan hydrolysis, which makes it a plausible candidate acting as a hydrolase against the peptidoglycan cell wall to allow the assembly of the T4SS apparatus. In the current study, the CHAP domain of VirB1-89K from S. suis 89K PAI was cloned and over-expressed in Escherichia coli, and its peptidoglycan-degrading activity in vitro was determined. The results indicated that the VirB1-89K CHAP domain can degrade the peptidoglycan layer of bacteria. Deletion of virB1-89K reduces significantly, but does not abolish, the virulence of S. suis in a mouse model.

Conclusions: The experimental results presented here suggested that VirB1-89K facilitates the assembly of 89K T4SS apparatus by catalyzing the degradation of the peptidoglycan cell wall, thus contributing to the pathogenesis of S. suis 2 infection.

Show MeSH
Related in: MedlinePlus