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Thermoregulation of Invasion Genes in Shigella Flexneri Through the Transcriptional Activation of the Virb Gene on the Large Plasmid

  • C. Sasakawa
  • T. Tobe
  • S. Nagai
  • N. Okada
  • B. Adler
  • K. Komatsu
  • M. Yoshikawa
Part of the Federation of European Microbiological Societies Symposium Series book series (FEMS, volume 58)

Summary

Expression of several invasion (inv) genes on the large virulence plasmid of Shigella flexneri is subject to thermoregulation. The ipaBCD genes are expressed at 37 C but not at 30 C and this expression is regulated by virF through the activation of virB on the plasmid. To identify the mediator gene for the thermoregulation of the large plasmid, the transcription of virF, virB, ipa and the other two inv operons was examined by Northern dot hybridization and S1 nuclease assay methods. The results indicated that transcription of virF and virB was affected by temperature but the level of virB transcription was more strongly controlled by temperature than that of virF. On the other hand, transcription of ipa and the other two inv operons was not dependent on temerature but on virB transcription. By overexpressing the virB gene with a tac promoter, deregulation of invasion phenotype was achieved in the absence of VirF function, suggesting that the transcriptional activation of virB mediates the thermoregulation phenomenon.

Keywords

Hemolytic Activity Invasion Phenotype Shigella Flexneri Large Plasmid virB Gene 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Adler, B., Sasakawa, C., Tobe, T., Makino, S., Komatsu, K., and Yoshikawa, M. 1989. A dual transcriptional activation system for the 230 kilobase plasmid genes coding for virulence-associated antigens of Shigella flexneri. Mol. Microbiol. 3:627PubMedCrossRefGoogle Scholar
  2. Dorman, C.J., Bhriain, N.N., and Higgins, C.F. 1990. DNA supercoiling and environmental regulation of virulence gene expression in Shigella flexneri. Nature 344:789PubMedCrossRefGoogle Scholar
  3. Higgins, C.F., Dorman, CJ., Stirling, D.A., Waddell, L., Booth, I.R., May, G., and Bremer, E. 1988. A physiological role for DNA supercoiling in the osmotic regulation of gene expression in S. typhimurium and E. coli Cell 52:569PubMedCrossRefGoogle Scholar
  4. Lett, M.-C, Sasakawa, C, Okada, N., Sakai, T., Makino, S., Yamada, M., Komatsu, K., and Yoshikawa, M. 1989. virG, a plasmid-coded virulence gene of Shigella flexneri: identification of the VirG protein and determination of the complete coding sequence. J.Bacteriol 171:353PubMedGoogle Scholar
  5. Makino, S., Sasakawa, C., Kamata, K., Kurata, T., and Yoshikawa, M. 1986. A genetic determinant required for con tinuous reinfection of adjacent cells on a large plasmid in S. flexneri 2a. Cell 46:551PubMedCrossRefGoogle Scholar
  6. Maurelli, A.T., Blackmon, B., and Curtiss III, R. 1984. Temperature-dependent expression of virulence genes in Shigella. Infect.Immun. 43:195PubMedGoogle Scholar
  7. Maurelli, A.T., and Sansonetti, P.J. 1988. Identification of a chromosomal gene controlling temperature-regulated expression of Shigella virulence. Proc.Natl.Acad.Sci.USA 85:2820PubMedCrossRefGoogle Scholar
  8. Sakai, T., Sasakawa, C., and Yoshikawa, M. 1988. Expression of four virulence antigens of Shigella flexneri is positively regulated at the transcriptional level by the 30 kiloDal ton virF protein. Mol.Microbiol. 2:589PubMedCrossRefGoogle Scholar
  9. Sansonetti, P.J., Pyter, A., Clerc, P., Maurelli, A.T., and Mounier, J. 1986. Multiplication of Shigella flexneri within HeLa cells: lysis of the phagocytic vacuole and plasmid-mediated contact hemolysis.Infect.Immun. 51:461PubMedGoogle Scholar
  10. Sasakawa, C, Kamata, K., Sakai, T., Makino, S., Yamada, M., Okada, N., and Yoshikawa, M. 1988. virulence-associated genetic regions comprising 31 kilobase of the 230-kilobase plasmid in Shigella flexneri 2a. J.Bacteriol. 170:2480PubMedGoogle Scholar
  11. Sasakawa, C., Adler, B., Tobe, T., Nagai, S., Komatsu, K., and Yoshikawa, M. 1989. Functional organization and nucleotide sequence of virulence Region-2 on the large virulence plasmid in Shigella flexneri 2a. Mol.Microbiol. 3:1191PubMedCrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1991

Authors and Affiliations

  • C. Sasakawa
    • 1
  • T. Tobe
    • 1
  • S. Nagai
    • 1
  • N. Okada
    • 1
  • B. Adler
    • 1
  • K. Komatsu
    • 1
  • M. Yoshikawa
    • 1
  1. 1.Institute of Medical ScienceUniversity of TokyoTokyoJapan

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