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Pleiotropic effects of the twin-arginine translocation system on biofilm formation, colonization, and virulence in Vibrio cholerae.

Zhang L, Zhu Z, Jing H, Zhang J, Xiong Y, Yan M, Gao S, Wu LF, Xu J, Kan B - BMC Microbiol. (2009)

Bottom Line: Deletion of the tatABC genes led to a significant decrease in biofilm formation, the ability to attach to HT-29 cells, and the ability to colonize suckling mouse intestines.In addition, we observed a reduction in the output of cholera toxin, which may be due to the decreased transcription level of the toxin gene in tatABC mutants, suggesting an indirect effect of the mutation on toxin production.No obvious differences in flagellum biosynthesis and motility were found between the tatABC mutant and the parental strain, showing a variable effect of Tat in different bacteria.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Department of Diarrheal Diseases, Chinese Center for Disease Control and Prevention, Beijing, PR China. zhanglijuan@icdc.cn

ABSTRACT

Background: The Twin-arginine translocation (Tat) system serves to translocate folded proteins, including periplasmic enzymes that bind redox cofactors in bacteria. The Tat system is also a determinant of virulence in some pathogenic bacteria, related to pleiotropic effects including growth, motility, and the secretion of some virulent factors. The contribution of the Tat pathway to Vibrio cholerae has not been explored. Here we investigated the functionality of the Tat system in V. cholerae, the etiologic agent of cholera.

Results: In V. cholerae, the tatABC genes function in the translocation of TMAO reductase. Deletion of the tatABC genes led to a significant decrease in biofilm formation, the ability to attach to HT-29 cells, and the ability to colonize suckling mouse intestines. In addition, we observed a reduction in the output of cholera toxin, which may be due to the decreased transcription level of the toxin gene in tatABC mutants, suggesting an indirect effect of the mutation on toxin production. No obvious differences in flagellum biosynthesis and motility were found between the tatABC mutant and the parental strain, showing a variable effect of Tat in different bacteria.

Conclusion: The Tat system contributes to the survival of V. cholerae in the environment and in vivo, and it may be associated with its virulence.

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Related in: MedlinePlus

Growth of V. cholerae tat mutants and complement strains in M9-TMAO media. The OD600 was measured when the strains were cultured at 37°C for 24 h. The OD600 value for each strain was the average of three samples.
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Figure 2: Growth of V. cholerae tat mutants and complement strains in M9-TMAO media. The OD600 was measured when the strains were cultured at 37°C for 24 h. The OD600 value for each strain was the average of three samples.

Mentions: To determine whether the Tat mutants still have a functional Tat system, a series of Tat gene mutants of the V. cholerae strain N16961 was constructed to determine their growth in the M9-TMAO media. By using reverse transcription-PCR assay, transcription of corresponding tat genes in all the mutants and complement mutants were confirmed, each of the deleted genes were negative in reverse transcription-PCR, and all the complemented genes became positive in each complement strain (data not shown). In E. coli, Tat mutants were unable to grow anaerobically with either dimethyl sulfoxide or TMAO as the sole terminal electron acceptor, unless complemented by functional tat genes, due to the negligible levels of periplasmic TMAO reductase [32,33]. The V. cholerae mutants included deletion mutants of tatABC (N169-dtatABC), tatABCE (N169-dtatABCE), tatB (N169-dtatB), tatC (N169-dtatC) and tatE (N169-dtatE) (Table 1). The mutant tatA (N169-dtatABC-BCcp) was obtained by complementation with pBAD-TatBC into strain N169-dtatABC, and the double mutant strain (N169-dtatABCE-BCcp) of tatA and tatE was obtained by complementation with pBAD-TatBC into strain N169-dtatABCE (Table 1). We found that the wild type V. cholerae strain N16961 and MG1655, the E. coli strain derived from K-12, could grow in in M9-TMAO media, whereas the mutants N169-dtatABC and N169-dtatABCE could not grow after being cultured at 37°C for 24 h (Fig. 2). However, when pBAD-TatABC was restored into the mutants N169-dtatABC and pBAD-TatABC was restored into N169-dtatABCE, the complementary strains could grow well in the M9-TMAO media, indicating that the tatABC cluster is essential in the function of the Tat system. N169-dtatE and N169-dtatABC-BCcp could grow in M9-TMAO media, although the OD600 values of these strains were slightly lower than that of N16961 (Fig. 2). In addition, the OD600 of N169-dtatB and N169-dtatC was noticeably lower than that of N16961 in M9-TMAO media (Fig. 2). Therefore, the tatB and tatC genes appear to be necessary for the V. cholerae Tat system, and tatA and tatE may functionally overlap in V. cholerae.


Pleiotropic effects of the twin-arginine translocation system on biofilm formation, colonization, and virulence in Vibrio cholerae.

Zhang L, Zhu Z, Jing H, Zhang J, Xiong Y, Yan M, Gao S, Wu LF, Xu J, Kan B - BMC Microbiol. (2009)

Growth of V. cholerae tat mutants and complement strains in M9-TMAO media. The OD600 was measured when the strains were cultured at 37°C for 24 h. The OD600 value for each strain was the average of three samples.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2698830&req=5

Figure 2: Growth of V. cholerae tat mutants and complement strains in M9-TMAO media. The OD600 was measured when the strains were cultured at 37°C for 24 h. The OD600 value for each strain was the average of three samples.
Mentions: To determine whether the Tat mutants still have a functional Tat system, a series of Tat gene mutants of the V. cholerae strain N16961 was constructed to determine their growth in the M9-TMAO media. By using reverse transcription-PCR assay, transcription of corresponding tat genes in all the mutants and complement mutants were confirmed, each of the deleted genes were negative in reverse transcription-PCR, and all the complemented genes became positive in each complement strain (data not shown). In E. coli, Tat mutants were unable to grow anaerobically with either dimethyl sulfoxide or TMAO as the sole terminal electron acceptor, unless complemented by functional tat genes, due to the negligible levels of periplasmic TMAO reductase [32,33]. The V. cholerae mutants included deletion mutants of tatABC (N169-dtatABC), tatABCE (N169-dtatABCE), tatB (N169-dtatB), tatC (N169-dtatC) and tatE (N169-dtatE) (Table 1). The mutant tatA (N169-dtatABC-BCcp) was obtained by complementation with pBAD-TatBC into strain N169-dtatABC, and the double mutant strain (N169-dtatABCE-BCcp) of tatA and tatE was obtained by complementation with pBAD-TatBC into strain N169-dtatABCE (Table 1). We found that the wild type V. cholerae strain N16961 and MG1655, the E. coli strain derived from K-12, could grow in in M9-TMAO media, whereas the mutants N169-dtatABC and N169-dtatABCE could not grow after being cultured at 37°C for 24 h (Fig. 2). However, when pBAD-TatABC was restored into the mutants N169-dtatABC and pBAD-TatABC was restored into N169-dtatABCE, the complementary strains could grow well in the M9-TMAO media, indicating that the tatABC cluster is essential in the function of the Tat system. N169-dtatE and N169-dtatABC-BCcp could grow in M9-TMAO media, although the OD600 values of these strains were slightly lower than that of N16961 (Fig. 2). In addition, the OD600 of N169-dtatB and N169-dtatC was noticeably lower than that of N16961 in M9-TMAO media (Fig. 2). Therefore, the tatB and tatC genes appear to be necessary for the V. cholerae Tat system, and tatA and tatE may functionally overlap in V. cholerae.

Bottom Line: Deletion of the tatABC genes led to a significant decrease in biofilm formation, the ability to attach to HT-29 cells, and the ability to colonize suckling mouse intestines.In addition, we observed a reduction in the output of cholera toxin, which may be due to the decreased transcription level of the toxin gene in tatABC mutants, suggesting an indirect effect of the mutation on toxin production.No obvious differences in flagellum biosynthesis and motility were found between the tatABC mutant and the parental strain, showing a variable effect of Tat in different bacteria.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Department of Diarrheal Diseases, Chinese Center for Disease Control and Prevention, Beijing, PR China. zhanglijuan@icdc.cn

ABSTRACT

Background: The Twin-arginine translocation (Tat) system serves to translocate folded proteins, including periplasmic enzymes that bind redox cofactors in bacteria. The Tat system is also a determinant of virulence in some pathogenic bacteria, related to pleiotropic effects including growth, motility, and the secretion of some virulent factors. The contribution of the Tat pathway to Vibrio cholerae has not been explored. Here we investigated the functionality of the Tat system in V. cholerae, the etiologic agent of cholera.

Results: In V. cholerae, the tatABC genes function in the translocation of TMAO reductase. Deletion of the tatABC genes led to a significant decrease in biofilm formation, the ability to attach to HT-29 cells, and the ability to colonize suckling mouse intestines. In addition, we observed a reduction in the output of cholera toxin, which may be due to the decreased transcription level of the toxin gene in tatABC mutants, suggesting an indirect effect of the mutation on toxin production. No obvious differences in flagellum biosynthesis and motility were found between the tatABC mutant and the parental strain, showing a variable effect of Tat in different bacteria.

Conclusion: The Tat system contributes to the survival of V. cholerae in the environment and in vivo, and it may be associated with its virulence.

Show MeSH
Related in: MedlinePlus