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Infection and Immunity, April 2008, p. 1509-1517, Vol. 76, No. 4
0019-9567/08/$08.00+0     doi:10.1128/IAI.01503-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Vibrio vulnificus rtxE Is Important for Virulence, and Its Expression Is Induced by Exposure to Host Cells{triangledown}

Byung Cheol Lee,2,{dagger} Jeong Hyun Lee,1,{dagger},§ Myung Won Kim,1 Byoung Sik Kim,1 Man Hwan Oh,1 Kun-Soo Kim,3 Tae Sung Kim,2* and Sang Ho Choi1*

National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul 151-742,1 School of Life Sciences and Biotechnology, Korea University, Seoul 136-701,2 Department of Life Science and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul 121-742, South Korea3

Received 12 November 2007/ Accepted 27 January 2008

Numerous secreted virulence factors have been proposed to account for the fulminating and destructive nature of Vibrio vulnificus infections. A mutant of V. vulnificus that exhibited less cytotoxicity to INT-407 human intestinal epithelial cells was screened from a library of mutants constructed by random transposon mutagenesis. A transposon-tagging method was used to identify and clone an open reading frame encoding an RTX toxin secretion ATP binding protein, RtxE, from V. vulnificus. The deduced amino acid sequence of RtxE from V. vulnificus was 91% identical to that reported from Vibrio cholerae. Functions of the rtxE gene in virulence were assessed by constructing an isogenic mutant whose rtxE gene was inactivated by allelic exchanges and by evaluating the differences between its virulence phenotype and that of the wild type in vitro and in mice. The disruption of rtxE blocked secretion of RtxA to the cell exterior and resulted in a significant reduction in cytotoxic activity against epithelial cells in vitro. Also, the intraperitoneal 50% lethal dose of the rtxE mutant was 104 to 105 times higher than that of the parental wild type, indicating that RtxE is essential for the virulence of V. vulnificus. Furthermore, the present study demonstrated that the rtxBDE genes are transcribed as one transcriptional unit under the control of a single promoter, PrtxBDE. The activity of V. vulnificus PrtxBDE is induced by exposure to INT-407 cells, and the induction requires direct contact of the bacteria with the host cells.

* Corresponding author. Mailing address for Sang Ho Choi: Department of Agricultural Biotechnology, Seoul National University, Seoul 151-742, South Korea. Phone: 82-2-880-4857. Fax: 82-2-873-5095. E-mail: choish{at}snu.ac.kr. Mailing address for Tae Sung Kim: School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, South Korea. Phone: 82-2-3290-3416. Fax: 82-2-3290-3921. E-mail: tskim{at}korea.ac.kr

{triangledown} Published ahead of print on 4 February 2008.

Editor: V. J. DiRita

{dagger} B.C.L. and J.H.L. contributed equally to this work.

§ Present address: Department of Bacteriology, University of Wisconsin, Madison, WI 53706.

Infection and Immunity, April 2008, p. 1509-1517, Vol. 76, No. 4
0019-9567/08/$08.00+0     doi:10.1128/IAI.01503-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Jones, M. K., Oliver, J. D. (2009). Vibrio vulnificus: Disease and Pathogenesis. Infect. Immun. 77: 1723-1733 [Full Text]  
  • Oh, M. H., Lee, S. M., Lee, D. H., Choi, S. H. (2009). Regulation of the Vibrio vulnificus hupA Gene by Temperature Alteration and Cyclic AMP Receptor Protein and Evaluation of Its Role in Virulence. Infect. Immun. 77: 1208-1215 [Abstract] [Full Text]  
  • Lee, D. H., Jeong, H. S., Jeong, H. G., Kim, K. M., Kim, H., Choi, S. H. (2008). A Consensus Sequence for Binding of SmcR, a Vibrio vulnificus LuxR Homologue, and Genome-wide Identification of the SmcR Regulon. J. Biol. Chem. 283: 23610-23618 [Abstract] [Full Text]  


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