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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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TMAO reductase detection in both cytoplasm and periplasm by the TMAO enzymatic assay. C, cytoplasm; P, periplasm; a, strain N169-dtatABC; b, strain N16961; c, strain N169-dtatABC (pBAD24); d, strain N169-dtatABC-cp.
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Figure 3: TMAO reductase detection in both cytoplasm and periplasm by the TMAO enzymatic assay. C, cytoplasm; P, periplasm; a, strain N169-dtatABC; b, strain N16961; c, strain N169-dtatABC (pBAD24); d, strain N169-dtatABC-cp.

Mentions: We also transformed pBAD-TatABC and pBAD-TatE, plasmids containing V. cholerae-derived tatABC and tatE, into the E. coli tat gene mutants [34] to assess if TatA or TatE is essential to Tat system. As shown in Table 2, pBAD-TatABC restored the growth of E. coli tatAE, tatB, tatC, and tatABCDE mutants in M9-TMAO media, whereas pBAD-TatE only restored the growth of the tatAE mutant. Therefore, V. cholerae tat genes can replace their E. coli counterparts to reconstitute a heterologous functional Tat system. Here it was also shown that tatE, located on chromosome II, may functionally overlap tatA in V. cholerae. The functionality of the Tat system was also confirmed by the subcellular distribution of TMAO reductase activity in the wild type strain N16961, the tatABC mutant strain N169-dtatABC, and strain N169-dtatABC-cp, N169-dtatABC restored with pBAD-TatABC. The prepared fractions of periplasm and cytoplasm were confirmed with the control of western blot assay, using the antibodies to β-lactamase and GroEL. It was shown that β-lactamase was predominantly in the extractd periplasmic fraction, while GroEL was mainly in the extracted cytoplasmic fraction [see Additional file 2]. As anticipated, the TMAO reductase activity was detected in the periplasm of the wild type strain N16961 and N169-dtatABC-cp, but it accumulated in the cytoplasm of N169-dtatABC (Fig. 3).


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)

TMAO reductase detection in both cytoplasm and periplasm by the TMAO enzymatic assay. C, cytoplasm; P, periplasm; a, strain N169-dtatABC; b, strain N16961; c, strain N169-dtatABC (pBAD24); d, strain N169-dtatABC-cp.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: TMAO reductase detection in both cytoplasm and periplasm by the TMAO enzymatic assay. C, cytoplasm; P, periplasm; a, strain N169-dtatABC; b, strain N16961; c, strain N169-dtatABC (pBAD24); d, strain N169-dtatABC-cp.
Mentions: We also transformed pBAD-TatABC and pBAD-TatE, plasmids containing V. cholerae-derived tatABC and tatE, into the E. coli tat gene mutants [34] to assess if TatA or TatE is essential to Tat system. As shown in Table 2, pBAD-TatABC restored the growth of E. coli tatAE, tatB, tatC, and tatABCDE mutants in M9-TMAO media, whereas pBAD-TatE only restored the growth of the tatAE mutant. Therefore, V. cholerae tat genes can replace their E. coli counterparts to reconstitute a heterologous functional Tat system. Here it was also shown that tatE, located on chromosome II, may functionally overlap tatA in V. cholerae. The functionality of the Tat system was also confirmed by the subcellular distribution of TMAO reductase activity in the wild type strain N16961, the tatABC mutant strain N169-dtatABC, and strain N169-dtatABC-cp, N169-dtatABC restored with pBAD-TatABC. The prepared fractions of periplasm and cytoplasm were confirmed with the control of western blot assay, using the antibodies to β-lactamase and GroEL. It was shown that β-lactamase was predominantly in the extractd periplasmic fraction, while GroEL was mainly in the extracted cytoplasmic fraction [see Additional file 2]. As anticipated, the TMAO reductase activity was detected in the periplasm of the wild type strain N16961 and N169-dtatABC-cp, but it accumulated in the cytoplasm of N169-dtatABC (Fig. 3).

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